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SCIENTIFIC AMERICAN SUPPLEMENT NO. 430




NEW YORK, MARCH 29, 1884

Scientific American Supplement. Vol. XVII, No. 430.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.


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TABLE OF CONTENTS.

I.    ENGINEERING, MECHANICS, ETC.--The Iron Industry In Brazil.--By
      Prof. P. FEHRAND.--Methods of obtaining iron.--Operation
      of the system.--Elaboration of the ore.--Setting up a forge.--
      Selling price of iron

      The Steamer Churchill, built by Messrs. Hall, Russell & Co., for
      service at Natal.--With full page of illustrations

      Three-Way Tunnels

      Falconetti's Continuously Primed Siphon.--Manner of carrying a
      water course over a canal, river, or road.--With engraving

      The Weibel-Piccard System of Evaporating Liquids.--
      2 illustrations

II.   TECHNOLOGY.--Coal Gas as a Labor--saving Agent in Mechanical
      Trades.--By T. FLETCHER.--Gas as fuel.--Arrangement of burners
      for disinfection, for drying glue, albumen, etc.--Best burners.
      --Gas bars for furnaces, etc.

      Instantaneous Photography.--Several illustrations

III.  ELECTRICITY, MAGNETISM, ETC.--Electric Launches.--A
      paper read before the Society of Arts by A. RECKENZAUN, and
      discussion on the same.--Advantages of electromotive power.--
      Cost of same.--Experimental electric launches

      First Experiments with the Electric Light.--Sir Humphry
      Davy's experiments in 1813,--With two engravings

      Electrical Grapnel for Submarine Cables and Torpedo Lines.--
      3 figures

      Hughes' New Magnetic Balance.--1 figure

      Apparatus for Measuring Small Resistances.--With engraving
      and diagram

      Terrestrial Magnetism.--Magnetism on railways.--Synchronous
      Seismology

IV.   ARCHITECTURE.--Adornments of the New Post Office at Leipzig.--
      2 engravings

V.    NATURAL HISTORY, ETC.--Comparison of Strength of Large
      and Small Animals.--By W. N. LOCKINGTON

      Oil in California

VI.   HORTICULTURE, BOTANY. ETC.--The Dodder.--A new parasitic
      plant.--With engraving

      Recent Botanical Investigations

VII.  MEDICINE, HYGIENE ETC.--Nutritive Value of Condiments.--By
      H. D. ABBOTT

VIII. MISCELLANEOUS.--Mont St. Michel, Normandy.--With engraving

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THE DODDER.


The genus _Cuscuta_ contains quite a number of species which go under
the common name of dodder, and which have the peculiarily of living as
parasites upon other plants. Their habits are unfortunately too well
known to cultivators, who justly dread their incursions among cultivated
plants like flax, hops, etc.

All parasitic plants, or at least the majority of them, have one
character in common which distinguishes them at first sight. In many
cases green matter is wanting in their tissues or is hidden by a
livid tint that strikes the observer. Such are the Orobanchaccæ, or
"broomropes," and the tropical Balanophoraceæ. Nevertheless, other
parasites, such as the mistletoe, have perfectly green leaves.

However this may be, the naturalist's attention is attracted every time
he finds a plant deprived of chlorophyl, and one in which the leaves
seem to be wanting, as in the dodder that occupies us. In fact, as the
majority of parasites take their nourishment at the expense of the
plants upon which they fasten themselves, they have no need, as a
general thing, of elaborating through their foliar organs the materials
that their hosts derive from the air; in a word, they do not breathe
actively like the latter, since they find the elements of their
nutrition already prepared in the sap of their nurses. The dodders,
then, are essentially parasites, and their apparent simplicity gives
them a very peculiar aspect. Their leaves are wholly wanting, or are
indicated by small, imperceptible scales, and their organs of vegetation
are reduced to a stem and filiform branches that have obtained for them
the names of _Cheveux de Venus_ (Venus' Hair) and _Cheveux du Diable_
(devil's hair) in French, and gold thread in English. Because of their
destructive nature they have likewise been called by the unpoetic name
of hellweed; and, for the reason that they embrace their host plants so
closely, they have been called love weed and love vine.

When a seed of _Cuscuta_, germinates, no cotyledons are to be
distinguished. This peculiarity, however, the plant has in common with
other parasites, and even with some plants, such as orchids, that
vegetate normally. The radicle of the dodder fixes itself in the earth,
and the little stem rises as in other dicotyledons; but soon (for the
plantlet could not live long thus) this stem, which is as slender as a
thread, seeks support upon some neighboring plant, and produces upon
its surfaces of contact one or more little protuberances that shortly
afterward adhere firmly to the support and take on the appearance and
functions of cupping glasses. At this point there forms a prolongation
of the tissue of the dodder--a sort of cone, which penetrates the stalk
of the host plant. After this, through the increase of the stem and
branches of the parasite, the supporting plant becomes interlaced on
every side, and, if it does not die from the embraces of its enemy, its
existence is notably hazarded. It is possible for a _Cuscuta_ plant to
work destruction over a space two meters in diameter in a lucern or
clover field; so, should a hundred seeds germinate in an acre, it may be
easily seen how disastrous the effects of the scourge would prove.

These enemies of our agriculture were scarcely to be regarded as
injurious not very many years ago, for the reason that their sources of
development were wanting. Lucern and clover are comparatively recent
introductions into France, at least as forage plants. Other cultures are
often sorely tried by the dodder, and what is peculiar is that there are
almost always species that are special to such or such a plant, so that
the botanist usually knows beforehand how to determine the parasite
whose presence is made known to him. Thus, the _Cuscuta_ of flax, called
by the French _Bourreau du Lin_ (the flax's executioner), and by the
English, flax dodder, grows only upon this textile plant, the crop of
which it often ruins. On account of this, botanists call this species
Cuscuta epilinum. Others, such as C. Europæa, attack by preference hemp
and nettle. Finally, certain species are unfortunately indifferent and
take possession of any plant that will nourish them. Of this number is
the one that we are about to speak of.

Attempts have sometimes been made out of curiosity to cultivate exotic
species. One of the head gardeners at the Paris Museum received
specimens of _Cuscuta reflexa_ from India about two years ago, and,
having placed it upon a geranium plant, succeeded in cultivating it.
Since then, other plants have been selected, and the parasite has been
found to develop upon all of them. What adds interest to this species
is that its flowers are relatively larger and that they emit a pleasant
odor of hawthorn. Mr. Hamelin thinks that by reason of these advantages,
an ornamental plant might be made of it, or at least a plant that would
be sought by lovers of novelties. Like the majority of dodders, this
species is an annual, so that, as soon as the cycle of vegetation is
accomplished, the plant dies after flowering and fruiting. But here the
seeds do not arrive at maturity, and the plant has to be propagated by
a peculiar method. At the moment when vegetation is active, it is only
necessary to take a bit of the stem, and then, after previously lifting
a piece of the bark of the plant upon which it is to be placed, to apply
this fragment of _Cuscuta_ thereto (as in grafting), place the bark over
it, and bind a ligature round the whole. In a short time the graft will
bud, and in a few months the host plant will be covered with it.

The genus _Cuscuta_ embraces more than eighty species, which are
distributed throughout the entire world, but which are not so abundant
in cold as in warm regions.--_La Nature_.

[Illustration: A NEW EXOTIC DODDER. (_Cuscuta Reflexa_.)]

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RECENT BOTANICAL INVESTIGATIONS.


It is commonly said that there is a great difference between the
transpiration and evaporation of water in plants. The former takes place
in an atmosphere saturated with moisture, it is influenced by light,
by an equable temperature, while evaporation ceases in a saturated
atmosphere. M. Leclerc has very carefully examined this question, and he
concludes that transpiration is only the simple evaporation of water. If
transpiration is more active in the plant exposed to the sun, that is
due to the heat rays, and in addition arises in part from the fact that
the assimilating action of chlorophyl heats the tissues, which in turn
raises the temperature and facilitates evaporation.

As to transpiration taking place in a saturated atmosphere, it is a
mistake; generally there is a difference in the temperature of the plant
and the air, and the air is not saturated in its vicinity. In a word,
transpiration and evaporation is the same thing.

Herr Reinke has made an interesting examination of the action of light
on a plant. He has permitted a pencil of sun rays to pass through a
converging lens upon a cell containing a fragment of an aquatic plant.
He was enabled to increase the intensity of the light, so that it should
be stronger or weaker than the direct sunlight. He could thus vary its
intensity from 1/16 of that of direct sunlight to an intensity 64 times
stronger. The temperature was maintained constant.

Herr Reinke has shown that the chlorophyl action increases regularly
with the light for intensities under that of direct sunlight; but what
is unexpected, that for the higher intensities above that of ordinary
daylight the disengagement of oxygen remains constant.

M. Leclerc du Sablon has published some of his results in his work on
the opening of fruits. The influences which act upon fruit are external
and internal. The external cause of dehiscence is drying. We can open or
shut a fruit by drying or wetting it. The internal causes are related to
the arrangement of the tissues, and we may say that the opening of fruit
can be easily explained by the contraction of the ligneous fibers under
drying influences. M. Leclerc shows by experiment that the fibers
contract more transversely than longitudinally, and that the thicker
fibers contract the most. This he finds is connected with the opening of
dry fruits.

Herr Hoffman has recently made some interesting experiments upon the
cultivation of fruits.

It is well known that many plants appear to select certain mineral soils
and avoid others, that a number of plants which prefer calcareous soils
are grouped together as _calcicoles_, and others which shun such ground
as _calcifuges_. Herr Hoffman has grown the specimen which has been
cited by many authors as absolutely calcifugic. He has obtained strong
plants upon a soil with 53 per cent. of lime, and these have withstood
the severe winter of 1879-1880, while individuals of the same species
grown on silicious ground have failed. This will modify the ideas of
agriculturists, at least in regard to this plant.

Herr Schwarz has been engaged in the study of the fine hairs of roots.
According to this author, there is a maximum and minimum of humidity,
between which there lies a mean of moisture, most favorable for the
development of these capillary rootlets, and this amount of moisture
varies with different plants. He finds that this growth of hair-like
roots is conditioned upon the development of the main root from which it
springs. In a weak solution of brine these fine roots are suppressed,
while the growth of the main root is continued. The changes of the
_milieu_ lead to changes in the form of the hairs, rendering them even
branched.

Signor Savastano has ventured to criticise as exaggerated the views of
Muller, Lubbock, and Allen on the adaptation of flowers to insects,
having noticed that bees visit numbers of flowers, and extract their
honey without touching the stigmas or pistils. He has also found them
neglecting flowers which were rich in honey and visiting others much
poorer. These observations have value, but cannot be considered as
seriously impairing the multiplied evidences of plant adaptation to
insect life.

Mr. Camus has shown that the flora of a small group of hills, the
Euganean Mountains, west of the Apennines and south of the Alps, has a
peculiar flora, forming an island in the midst of a contrasted flora
existing about it. Here are found Alpine, maritime, and exotic plants
associated in a common isolation.--_Revue Scientifique_.

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RECENT BOTANICAL ADVANCES.


Among the most significant of the recent discoveries in botany, is that
respecting the continuity of the protoplasm from cell to cell, by means
of delicate threads which traverse channels through the cell walls. It
had long been known, that in the "sieve" tissues of higher plants there
was such continuity through the "sieve plates," which imperfectly
separated the contiguous cells. This may be readily seen by making
longitudinal sections of a fibro-vascular bundle of a pumpkin stem,
staining with iodine, and contracting the protoplasm by alcohol.
Carefully made specimens of the soft tissues of many plants have shown
a similar protoplasmic continuity, where it had previously been
unsuspected. Some investigators are now inclined to the opinion that
protoplasmic continuity may be of universal occurrence in plants.

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ELECTRIC LAUNCHES.

[Footnote: A recent lecture before the Society of ATM, London.]

By A. RECKENZAUN.


It is not my intention to treat this subject from a shipwright's point
of view. The title of this paper is supposed to indicate a mode of
propelling boats by means of electrical energy, and it is to this motive
power that I shall have the honor of drawing your attention.

The primary object of a launch, in the modern sense of the word, lies
in the conveyance of passengers on rivers and lakes, less than for the
transport of heavy goods; therefore, it may not be out of place to
consider the conveniences arising from the employment of a motive power
which promises to become valuable as time and experience advance. In a
recent paper before the British Association at Southport, I referred to
numerous experiments made with electric launches; now it is proposed
to treat this subject in a wider sense, touching upon the points of
convenience in the first place; secondly, upon the cost and method of
producing the current of electricity; and thirdly, upon the construction
and efficiency of the propelling power and its accessories.

Whether it is for business, pleasure, or war purposes a launch should
be in readiness at all times, without requiring much preparation or
attention. The distances to be traversed are seldom very great, fifty to
sixty miles being the average.

Nearly the whole space of a launch should be available for the
accommodation of passengers, and this is the case with an electrically
propelled launch. We have it on good authority, that an electric launch
will accommodate nearly double the number of passengers that a
steam launch of the same dimensions would; therefore, for any given
accommodation we should require a much smaller vessel, demanding less
power to propel it at a given rate of speed, costing less, and affording
easier management.

A further convenience arising from electromotive power is the absence of
combustibles and the absence of the products of combustion-matters of
great importance; and for the milder seasons, when inland navigation
is principally enjoyed, the absence of heat, smell, and noise, and,
finally, the dispensing with one attendant on board, whose wages, in
most cases, amount to as much or more than the cost of fuel, besides the
inconvenience of carrying an additional individual.

I do not know whether the cost of motive power is a serious
consideration with proprietors of launches, but it is evident that if
there be a choice between two methods of equal qualities, the most
economical method will gain favor. The motive power on the electric
launch is the electric current; we must decide upon the mode of
procuring the current. The mode which first suggested itself to
Professor Jacobi, in the year 1838, was the primary battery, or the
purely chemical process of generating electricity.

Jacobi employed, in the first instance, a Daniell's battery, and in
later experiments with his boat on the river Neva, a Grove's battery.
The Daniell's battery consisted of 320 cells containing plates of copper
and zinc; the speed attained by the boat with this battery did not reach
one mile and a quarter per hour; when 64 Grove cells were substituted,
the speed came to two and a quarter miles per hour; the boat was 38
feet long. 7½ beam, and 3 feet deep. The electromotor was invented by
Professor Jacobi; it virtually consisted of two disks, one of which was
stationary, and carried a number of electromagnets, while the other disk
was provided with pieces of iron serving as armatures to the pole pieces
of the electromagnets, which were attracted while the electric current
was alternately conveyed through the bobbins by means of a commutator,
producing continuous rotation.

We are not informed as to the length of time the batteries were enabled
to supply the motor with sufficient current, but we may infer from the
surface of the acting materials in the battery that the run was rather
short; the power of the motor was evidently very small, judging by the
limited speed obtained, but the originality of Jacobi deserves comment,
and for this, as well as for numerous other researches, his name will be
remembered at all times.

It may not be generally known that an electric launch was tried for
experimental purposes, on a lake at Pentlegaer, near Swansea. Mr. Robert
Hunt, in the discussion of his paper on electromagnetism before the
Institution of Civil Engineers in 1858, mentioned that he carried on an
extended series of experiments at Falmouth, and at the instigation of
Benkhausen, Russian Consul-General, he communicated with Jacobi upon the
subject. In the year 1848, at a meeting of the British Association at
Swansea, Mr. Hunt was applied to, by some gentlemen connected with the
copper trade of that part, to make some experiments on the electrical
propulsion of vessels; they stated, that although electricity might
cost thirty times as much as the power obtained from coal it would,
nevertheless, be sufficiently economical to induce its employment for
the auxiliary screw ships employed in the copper trade with South
America.

The boat at Swansea was partly made under Mr. (now Sir William) Grove's
directions, and the engine was worked on the principle of the old toys
of Ritchie, which consisted of six radiating poles projecting from a
spindle, and rotating between a large electro-magnet. Three persons
traveled in Hunt's boat, at the rate of three miles per hour. Eight
large Grove's cells were employed, but the expense put it out of
question as a practical application.

Had the Gramme or Siemens machine existed at that time, no doubt the
subject would have been further advanced, for it was not merely the cost
of the battery which stood in the way, but the inefficient motor, which
returned only a small fraction of the power furnished by the zinc.

Professor Silvanus Thompson informs us that an electric boat was
constructed by Mr. G. E. Dering, in the year 1856, at Messrs. Searle's
yard, on the River Thames; it was worked by a motor in which rotation
was effected by magnets arranged within coils, like galvanometer
needles, and acted on successively by currents from a battery.

From a recent number of the _Annales de l'Electricite_, we learn that
Count de Moulins experimented on the lake in the Bois de Boulogne, in
the year 1866, with an iron flat-bottomed boat, carrying twelve persons.
Twenty Bunsen cells furnished the current to a motor on Froment's
principle turning a pair of paddle wheels.

In all these reports there is a lack of data. We are interested to
know what power the motors developed, the time and speed, as well as
dimensions and weights.

Until Trouve's trip on the Seine, in 1881, and the launch of the
Electricity on the Thames, in 1882, very little was known concerning the
history of electric navigation.

M. Trouve originally employed Plante's secondary battery, but afterward
reverted to a bichromate battery of his own invention. In all the
primary batteries hitherto applied with advantage, zinc has been used as
the acting material. Where much power is required, the consumption of
zinc amounts to a formidable item; it costs, in quantity, about 3d. per
pound, and in a well arranged battery a definite quantity of zinc is
transformed. The final effect of this transformation manifests itself in
electrical energy, amounting to about 746 watts, or one electrical horse
power for every two pounds of this metal consumed per hour. The cost of
the exciting fluid varies, however, considerably; it may be a solution
of salts, or it may be dilute acid. Considering the zinc by itself, the
expense for five electrical or four mechanical horse power through an
efficient motor, in a small launch, would be 2s. 6d. per hour. Many
persons would willingly sacrifice 2s. 6d per hour for the convenience,
but a great item connected with the employment of zinc batteries is
in the exciting fluid, and the trouble of preparing the zinc plates
frequently. The process of cleaning, amalgamating and refilling is so
tedious, that the use of primary batteries for locomotive purposes is
extremely limited. To recharge a Bunsen, Grove, or bichromate battery,
capable of giving six or seven hours' work at the rate of five
electrical horse power, would involve a good day's work for one man; no
doubt he would consider himself entitled to a full day's wages, with the
best appliances to assist him in the operation.

Several improved primary batteries have recently been brought out, which
promise economical results. If the residual compound of zinc can be
utilized, and sold at a good price, then the cost of such motive power
may be reduced in proportion to the value of those by-products.

For the purpose of comparison, let us now employ the man who would
otherwise clean and prepare the primary cells, at engine driving. We let
him attend to a six horse power steam engine, boiler, and dynamo machine
for charging 50 accumulators, each of a capacity of 370 ampere hours, or
one horse power hour. The consumption of fuel will probably amount to 40
lb. per hour, which, at the rate of 18s. a ton, will give an expenditure
of nearly 4d. per hour. The energy derived from coal in the accumulator
costs, in the case of a supply of five electrical horse power for seven
hours, 2s. 9d.; the energy derived from the zinc in a primary battery,
supplying five electrical horse power for seven hours, would cost 17s.
3d.

It is hardly probable that any one would lay down a complete plant,
consisting of a steam or gas engine and dynamo, for the sole purpose of
charging the boat cells, unless such a boat were in almost daily use, or
unless several boats were to be supplied with electrical power from one
station. In order that electric launches may prove useful, it will be
desirable that charging stations should be established, and on many of
the British and Irish rivers and lakes there is abundance of motive
power, in the shape of steam or gas engines, or water-wheels.

A system of hiring accumulators ready for use may, perhaps, best satisfy
the conditions imposed in the case of pleasure launches.

It is difficult to compile comparative tables showing the relative
expenses for running steam launches, electric launches with secondary
batteries, and electric launches with primary zinc batteries; but I
have roughly calculated that, for a launch having accommodation for a
definite number of passengers, the total costs are as 1, 2.5, and 12
respectively, steam being lowest and zinc batteries highest.

The accumulators are, in this case, charged by a small high pressure
steam engine, and a very large margin for depreciation and interest on
plant is added. The launch taken for this comparison must run during
2,000 hours in the year, and be principally employed in a regular
passenger service, police and harbor duties, postal service on the lakes
and rivers of foreign countries, and the like.

The subject of secondary batteries has been so ably treated by Professor
Silvanus Thompson and Dr. Oliver Lodge, in this room, that I should
vainly attempt to give you a more complete idea of their nature. The
improvements which are being made from time to time mostly concern
mechanical details, and although important, a description will scarcely
prove interesting.

A complete Faure-Sellon-Volckmar cell, such as is used in the existing
electric launches, is here on the table; this box weighs, when ready
for use, 56 lb.; and it stores energy equal to one horse power for one
hour=1,980,000 foot pounds, or about one horse power per minute for each
pound weight of material. It is not advantageous to withdraw the whole
amount of energy put in; although its charging capacity is as much as
370 ampere hours, we do not use more than 80 per cent., or 300 ampere
hours; hence, if we discharge these accumulators at the rate of 40
amperes, we obtain an almost constant current for 7½ hours: one cell
gives an E.M.F. of two volts. In order to have a constant power of one
horse for 7½ hours, at the rate of 40 amperes discharge, we must have
more than nine cells per electrical horsepower; and 47 such cells will
supply five electrical horse power for the time stated, and these 47
cells will weigh 2,633 lb.

We could employ half the number of cells by using them at the rate of
80 amperes, but then they will supply the power for less than half the
time. The fact, however, that the cells will give so high a rate of
discharge for a few hours is, in itself, important, since we are enabled
to apply great power if desirable; the 47 cells above referred to can
be made to give 10 or 12 electrical horse power for over two hours, and
thus propel the boat at a very high speed, provided that the motor is
adapted to utilize such powerful currents.

The above mentioned weight of battery power--viz., 2,632 lb., to
which has to be added the weight of the motor and the various
fittings--represents, in the case of a steam launch, the weight of
coals, steam boiler, engine, and fittings. The electro motor capable of
giving four horse power on the screw shaft need not weigh 400 lb. if
economically designed; this added to the weight of the accumulators, and
allowing a margin for switches and leads, brings the whole apparatus up
to about 28 cwt.

An equally powerful launch engine and boiler, together with a maximum
stowage of fuel, will weigh about the same. There is, however, this
disadvantage about the steam power, that it occupies the most valuable
part of the vessel, taking away some eight or nine feet of the widest
and most convenient part, and in a launch of twenty-four feet length,
requiring such a power as we have been discussing, this is actually
one-third of the total length of the vessel, and one-half of the
passenger accommodation; therefore, I may safely assert that an electric
launch will carry about twice as many people as a steam launch of
similar dimensions.

The diagram on the wall represents sections of an electric launch built
by Messrs. Yarrow and Company, and fitted up by the Electrical Power
Storage Company, for the recent Electrical Exhibition in Vienna. She has
made a great number of successful voyages on the River Danube during the
autumn. Her hull is of steel, 40 feet long and 6 feet beam, and there
are seats to accommodate forty adults comfortably. Her accumulators are
stowed away under the floor, so is the motor, but owing to the lines of
the boat the floor just above the motor is raised a few inches. This
motor is a Siemens D2 machine, capable of working up to seven horse
power with eighty accumulators.

In speaking of the horse power of an electro motor, I always mean the
actual power developed in the shaft, and not the electrical horse power;
this, therefore, should not be compared to the indicated horse power of
a steam engine.

I am indebted to Messrs. Yarrow for the principal dimensions and other
particulars of a high pressure launch engine and boiler, such as would
be suitable for this boat. From these dimensions I prepared a second
diagram representing the steam power, and when placed in position it
will show at a glance how much space this apparatus will occupy. The
total length lost in this way amounts to 12 feet, leaving for testing
capacity only 15 feet, while that of the electric launch is 27 feet
on each side of the boat; thus the accommodation is as fifteen to
twenty-seven, or as twenty-two passengers to forty, in favor of the
electric launch.

Comparing the relative weights of the steam power and the electric power
for this launch, we find that they are nearly equal--each approaches 50
cwt; but in the case of the steam launch we include 10 cwt. of coals,
which can be stowed into the bunkers, and which allow fifteen hours
continuous steaming, whereas the electric energy stored up will only
give us seven and a half hours with perfect safety.

I have here allowed 8 lb. of coal per indicated horse power per hour,
and 10 horse power giving off 7 mechanical horse power on the screw
shaft; this is an example of an average launch engine. There are launch
engines in existence which do not consume one-half that amount of fuel,
but these are so few, so rare, and so expensive, that I have neglected
them in this account.

Not many years ago, a steam launch carrying a seven hours supply of fuel
was considered marvelous.

Our present accumulaton supplies 33,000 foot pounds of work per pound of
lead, but theoretically one pound of lead manifests an energy equal to
360,000 foot pounds in the separation from its oxide; and in the case of
iron, Prof. Osborne Reynolds told us in this place, the energy evolved
by its oxidation is equivalent to 1,900,000 foot pounds per pound of
metal. How nearly these limits may be approached will he the problem
of the chemist; to prophesy is dangerous, while science and its
applications are advancing at this rapid rate.

Theoretically, then, with our weight of fully oxidized lead we should be
able to travel for 82 hours; with the same weight of iron for 430 hours,
or 18 days and nights continually, at the rate of 8 miles per hour, with
one change. Of course, these feats are quite impossible. We might as
well dream of getting 5 horse power out of a steam engine for one pound
of coal per hour.

While the chemist is busy with his researches for substances and
combinations which will yield great power with small quantities of
material, the engineer assiduously endeavors to reconvert the chemical
or electrical energy into mechanical work suitable to the various needs.

To get the maximum amount of work with a minimum amount of weight, and
least dimensions combined with the necessary strength is the province
of the mechanical engineer--it is a grand and interesting study; it
involves many factors; it is not, as in the steam engine and hydraulic
machine, a matter of pressures, tension and compression, centrifugal and
static forces, but it comprises a still larger number of factors, all
bearing a definite relation to each other.

With dynamo machines the aim has been to obtain as nearly as possible
as much electrical energy out of the machine as has been put in by the
prime mover, irrespective of the quantity of material employed in its
construction. Dr. J. Hopkinson has not only improved upon the Edison
dynamo, and obtained 94 per cent. of the power applied in the form of
electrical energy, but he got 50 horse power out of the same quantity of
iron and copper where Edison could only get 20 horsepower--and, though
the efficiency of this generator is perfect, it could not be called an
efficient motor, suitable for locomotion by land or water, because it
is still too heavy. An efficient motor for locomotion purposes must not
only give out in mechanical work as nearly as possible as much as the
electrical energy put in, but it must be of small weight, because it has
to propel itself along with the vehicle, and every pound weight of
the motor represents so many foot pounds of energy used in its own
propulsion; thus, if a motor weighed 660 pounds, and were traveling at
the rate of 50 feet per minute, against gravitation, it would expend
33,000 foot pounds per minute in moving itself, and although this
machine may give 2 horse power, with an efficiency of 90 per cent.
it would, in the case of a boat or a tram-car, be termed a wasteful
machine. Here we have an all-important factor which can be neglected,
to a certain extent, in the dynamo as a generator, although from an
economical point of view excessive weight in the dynamo must also be
carefully avoided.

The proper test for an electro-motor, therefore, is not merely its
efficiency, or the quotient of the mechanical power given out, divided
by the electrical energy put in, but also the number of feet it could
raise its own weight in a given space of time, with a given current, or,
in other words, the number of foot pounds of work each pound weight of
the motor would give out.

The Siemens D2 machine, as used in the launch shown in the diagram on
the wall, is one of the lightest and best motors, it gives 7 horse power
on the shaft, with an expenditure of 9 electrical horsepower, and it
weighs 658 lb.; its efficiency, therefore, 7/5 or nearly 78 per cent.;
but its "coefficient" as an engine of locomotion is 351--that is to say,
each pound weight of the motor will yield 351 foot pounds on the shaft.
We could get even more than 7 horse power out of this machine, by either
running it at an excessive speed, or by using excessive currents; in
both cases, however, we should shorten the life of the apparatus.

An electro-motor consists, generally, of two or more electro-magnets so
arranged that they continually attract each other, and thereby convey
power. As already stated, there are numerous factors, all bearing a
certain relationship to each other, and particular rules which hold
good in one type of machine will not always answer in another, but the
general laws of electricity and magnetism must be observed in all cases.
With a given energy expressed in watts, we can arrange a quantity of
wire and iron to produce a certain quantity of work; the smaller the
quantity of material employed, and the larger the return for the energy
put in, the greater is the total efficiency of the machine.

Powerful electro-magnets, judiciously arranged, must make powerful
motors. The ease with which powerful electro-magnets can be constructed
has led many to believe that the power of an electro-motor can be
increased almost infinitely, without a corresponding increase of energy
spent. The strongest magnet can be produced with an exceedingly
small current, if we only wind sufficient wire upon an iron core. An
electro-magnet excited by a tiny battery of 10 volts, and, say,
one ampere of current, may be able to hold a tremendous weight in
suspension, although the energy consumed amounts to only 10 watts, or
less than 1/75 of a horse power, but the suspended weight produces no
mechanical work. Mechanical work would only be done if we discontinued
the flow of the current, in which case the said weight would drop; if
the distance is sufficiently small, the magnet could, by the application
of the current from the battery, raise the weight again, and if that
operation is repeated many times in a minute, then we could determine
the mechanical work performed. Assuming that the weight raised is 1,000
lb., and that we could make and break the current two hundred times
a minute, then the work done by the falling mass could, under no
circumstances, equal 1/75 of a horse-power, or 440 foot-pounds; that is,
1,000 lb. lifted 2.27 feet high in a minute, or about one-eighth of an
inch for each operation: hence the mere statical pull, or power of the
magnet, does in no way tend to increase the energy furnished by the
battery or generator, for the instant we wish to do work we must have
motion--work being the product of mass and distance.

Large sums of money have virtually been thrown away in the endeavor
to produce energy, and there are intelligent persons who to this day
imagine that, by indefinitely increasing the strength of a magnet, more
power may be got out of it than is put in.

Large field-magnets are advantageous, and the tendency in the
manufacture of dynamo machines has been to increase the mass of iron,
because with long and heavy cores and pole pieces there is a steady
magnetism insured, and therefore a steady current, since large masses
of iron take a long time to magnetize and demagnetize; thus very slight
irregularites in the speed of an armature are not so easily perceived.
In the case of electro-motors these conditions are changed. In the first
place, we assume that the current put through the coils of the magnets
is continuous; and secondly, we can count upon the momentum of the
armature, as well as the momentum of the driven object, to assist us
over slight irregularities. With electric launches we are bound
to employ a battery current, and battery currents are perfectly
continuous--there are no sudden changes; it is consequently a question
as to how small a mass of iron we may employ in our dynamo as a motor
without sacrificing efficiency. The intensity of the magnetic field
must be got by saturating the iron, and the energy being fixed, this
saturation determines the limit of the weight of the iron. Soft wrought
iron, divided into the largest possible number of pieces, will serve
our purpose best. The question of strength of materials plays also an
important part. We cannot reduce the quantity and division to such a
point that the rigidity and equilibrium of the whole structure is in any
way endangered.

The armature, for instance, must not give way to the centrifugal forces
imposed upon it, nor should the field magnets be so flexible as to yield
to the statical pull of the magnetic poles. The compass of this paper
does not permit of a detailed discussion of the essential points to be
observed in the construction of electro-motors; a reference to the main
points, may, however, be useful. The designer has, first of all, to
determine the most effective positions of the purely electrical and
magnetic parts; secondly, compactness and simplicity in details;
thirdly, easy access to such parts as are subject to wear and
adjustment; and, fourthly, the cost of materials and labor. The internal
resistance of the motor should be proportioned to the resistances of the
generator and the conductors leading from the generator to the receiver.

The insulation resistances must be as high as possible; the insulation
can never be too good. The motor should he made to run at that speed
at which it gives the greatest power with a high efficiency, without
heating to a degree which would damage the insulating material.

Before fixing a motor in its final position, it should also be tested
for power with a dynamometer, and for this purpose a Prony brake answers
very well.

An ammeter inserted in the circuit will show at a glance what current is
passing at any particular speed, and voltmeter readings are taken at the
terminals of the machine, when the same is standing still as well as
when the armature is running, because the E.M.F. indicated when the
armature is at rest alone determines the commercial efficiency of the
motor, whereas the E M.F. developed during motion varies with the speed
until it nearly reaches the E.M.F. in the leads; at that point the
theoretical efficiency will be highest.

Calculations are greatly facilitated, and the value of tests can be
ascertained quickly, if the constant of the brake is ascertained; then
it will be simply necessary to multiply the number of revolutions and
the weight at the end of the lever by such a constant, and the product
gives the horse power, because, with a given Prony brake, the only
variable quantities are the weight and the speed. All the observations,
electrical and mechanical, are made simultaneously. The electrical horse
power put into the motor is found by the well known formula C x E / 746;
this simple multiplication and division becomes very tedious and even
laborious if many tests have to be made in quick succession, and to
obviate this trouble, and prevent errors, I have constructed a horse
power diagram, the principle of which is shown in the diagram (Fig. 1).

Graphic representations are of the greatest value in all comparative
tests. Mr. Gisbert Kapp has recently published a useful curve in the
_Electrician_, by means of which one can easily compare the power and
efficiency at a glance (Fig. 2).

The speeds are plotted as abscissae, and the electrical work absorbed
in watts divided by 746 as ordinates; then with a series-wound motor we
obtain the curve, EE. The shape of this curve depends on the type of
the motor. Variation of speed is obtained by loading the brake with
different weights. We begin with an excess of weight which holds the
motor fast, and then a maximum current will flow through it without
producing any external work. When we remove the brake altogether, the
motor will run with a maximum speed, and again produce no external work,
but in this case very little current will pass; this maximum speed is om
on the diagram. Between these two extremes external work will be done,
and there is a speed at which this is a maximum. To find these speeds we
load the brake to different weights, and plot the resulting speeds and
horse powers as abscissae and ordinates producing the curve, BB. Another
curve,

e = B/E

made with an arbitrary scale, gives the commercial efficiency; the speed
for a maximum external horse power is o a, and the speed for the highest
efficiency is represented by o b. In practice it is not necessary to
test a motor to the whole limits of this diagram; it will be sufficient
to commence with a speed at which the efficiency becomes appreciable,
and to leave off with that speed which renders the desired power.

I have now to draw your attention to a new motor of my own invention, of
the weight of 124 lb., which, at 1,550 revolutions, gives 31 amperes and
61.5 volts at terminals. The mechanical horse power is 1.37, and the
coefficient 373.

                                                     Ohms.
Armature resistance                                    0.4 w.
Field-magnet resistance                               0.17 w.
Insulation resistance                            1,500,000 w.

This motor was only completed on the morning before reading the paper;
it could not, therefore, be tested as to its various capacities.

We have next to consider the principle of applying the motive power to
the propulsion of a launch. The propellers hitherto practically applied
in steam navigation are the paddle-wheel and the screw. The experience
of modern steam navigation points to the exclusive use and advantage of
the screw propeller where great speed of shaft is obtainable, and the
electric engine is pre-eminently a high-speed engine, consequently the
screw appears to be most suitable to the requirements of electric boats.
By simply fixing the propeller to the prolonged motor shaft, we complete
the whole system, which, when correctly made, will do its duty in
perfect order, with an efficiency approaching theory to a high degree.

[Illustration: FIG. 1.--RECKENZAUN'S ELECTRICAL HORSE POWER DIAGRAM.

Draw a square, A B C D--divide B C into 746 parts, and C D into 1,000
parts, or, generally, let a division on C D be 0.746 of a division on B
C, so that we can use the horizontal lines cutting A B as a horse power
scale. A B, in the above diagram, gives 1,000 horse power, if the line
B C represents 746 volts, and C D 1,000 amperes. Let x = any number of
volts, y the amperes, and h the horse power, then

h/x = y/100 :. h = xy/746

A fine wire or thread stretched from o as a center to the required
division on C D will facilitate references.]

Whatever force may be imparted to the water by a propeller, such force
can be resolved into two elements, one of which is parallel, and the
other in a plane at right angles to the keel. The parallel force alone
has the propelling effect; the screw, therefore, should always be so
constructed that its surfaces shall be chiefly employed in driving the
water in a direction parallel to the keel from stem to stern.

[Illustration: Fig. 2--KAPP'S DIAGRAM.]

It is evident that a finely pitched screw, running at a high velocity,
will supply these conditions best. With that beautiful screw lying on
this table, and made by Messrs. Yarrow, 95 per cent. of efficiency
has been obtained when running at a speed of over 800 revolutions per
minute--that is to say, only 5 per cent was lost in slip.

Reviewing the various points of advantage, it appears that electricity
will, in time to come, be largely used for propelling launches, and,
perhaps, something more than launches.

In conclusion, quoting Dr. Lardner's remarks on the subject of steam
navigation of nearly fifty years ago, he said:

"Some, who, being conversant with the actual conditions of steam
engineering as applied to navigation, and aware of various commercial
conditions which must affect the problem, were enabled to estimate
calmly and dispassionately the difficulties and drawbacks, as well as
the disadvantages, of the undertaking, entertained doubts which clouded
the brightness of their hopes, and warned the commercial world against
the indulgence of too sanguine anticipation of the immediate and
unqualified realization of the project. They counseled caution and
reserve against an improvident investment of extensive capital in
schemes which still be only regarded as experimental, and which might
prove its grave. But the voice of remonstrance was drowned amid the
enthusiasm excited by the promise of an immediate practical realization
of a scheme so grand.

"It cannot," he continues, "be seriously imagined that any one who
had been conversant with the past history of steam navigation could
entertain the least doubt of the abstract practicability of a steam
vessel making the voyage between Bristol and New York. A steam vessel,
having as cargo a couple of hundred tons of coals, would, _cæteris
paribus_, be as capable of crossing the Atlantic as a vessel
transporting the same weight of any other cargo."

Dr. Lardner is generally credited with having asserted that a steam
voyage across the Atlantic was "a physical impossibility," but in the
work from which I took the liberty of copying his words he denies the
charge, and says that what he did affirm was, that long sea voyages
could not at that time be maintained with that regularity and certainty
which are indispensable to commercial success, by any revenue which
could be expected from traffic alone.

The practical results are well known to us. History repeats itself, and
the next generation may put on record our week attempts, our doubts and
fears of this day. Whether electricity will ever rival steam, remains
yet to be proved; we may be on the threshold of great things. The
premature enthusiasm has subsided, and we enter upon the road of steady
progress.

Mr. Wm. H. Preece, the chairman, in inviting discussion, said that no
doubt those present would like to know something about the cost of such
a boat as Mr. Reckenzaun described, and he hoped that gentleman would
give them some information on that point.

Admiral Selwyn thought Mr. Reckenzaun was a little below the mark when
he talked about the dream of getting 5 horse power for one pound--he
would not say of coal, but of fuel. For some months he had seen ½ lb. of
fuel produce 1 horse power, and he knew it could be done. That fuel was
condensed concentrated fuel in the shape of oil. When this could be
done, electrical energy also could be obtained much cheaper, but if it
were extended to yachts, he thought that would be as far as any one now
present could be expected to see it go. Still he thought there was a
future for it, and that future would be best advanced by considering the
question on which he had touched. First, the employment of a cheaper
mode of getting the power in the steam engine; and, secondly, a cheaper
and higher secondary battery. In a railway train weight was a formidable
affair, but in a floating vessel it was still more important. He did
not think, however, that a light secondary battery was by any means an
impossibility. Mr. Loftus Perkins had actually produced by improvements
in the boiler and steam engine two great things: first, one indicated
horse power for a pound of fuel per hour, and next he had devised a
steam engine of 100 horse power, of a weight of only 84 lb. per horse
power, instead of 304 lb., which was about the average. Those were two
enormous steps in advance, and under a still more improved patent law he
had no doubt things would be brought forward which would show a still
greater progress. Within the last fifteen days, nearly 2,000 patents
had been taken out, as against 5,000 in the whole of the previous year,
which showed how operative a very small and illusory inducement had been
to encourage invention. He had long been known as an advocate of patent
law reform, and, therefore, felt bound to lose no opportunity of calling
attention to its importance. Invention was in the hands of the inventor,
the creator of trade. If, without robbing anybody, one wished to produce
property, it must be done by improving manufactures as a consequence
of inventions. In one instance alone it bad been proved that a single
invention had been the means of introducing twenty millions annually,
upon which income tax was paid.

Mr. Crampton said he did not think steam could ever compete with
electricity, under certain circumstances; but, at the same time, it
would be a long time before it was superseded. He should like very much
to see the compressed oil, one-sixth of a pound of which would give 1
horse power per hour.

Admiral Selwyn said he had seen a common Cornish boiler doing it years
ago.

Mr. Crampton said it had never come under his notice, and he had no
hesitation in saying that no such duty ever was performed by any oil,
because he never heard of any oil which evaporated more than eighteen to
twenty-two pounds of water per pound. However, he was delighted to hear
of such progress being made, and though he had been for so many years
connected with steam, he never expected it would last forever. He was
now making experiments for some large shipowners, for the purpose of
facilitating feeding and doing away with dust, but let him succeed to
what extent he might, steam would never compete with electricity for
such small vessels as these launches.

The Chairman asked if he rightly understood Admiral Selwyn that he had
recently seen an invention in which one-sixth of a pound of condensed
fuel would give 1 horse power per hour.

Admiral Selwyn said it was now some years ago since he saw this going
on, but the persons who did it did not know how or why it was done.
He had studied the question for the last ten years, and now knew the
_rationale_ of it, and would be prepared shortly to publish it. He knew
that 22 was the theoretical calorific value of the pound of oil, and
never supposed that oil alone would give 46 lb., which he saw it doing.
He had found out that by means of the oil forming carbon constantly in
the furnace, the hydrogen of the steam was burned, and that it was a
fallacy to suppose that an equal quantity of heat was used in raising
steam, at a pressure of, say, 120 lb. to the square inch, as the
hydrogen was capable of developing when properly burned. There were,
however, conditions under which alone that combustion could take
place--one being that the heat of the chamber must be 3,700°, and that
carbon must be constantly formed.

Mr. Gumpel said with regard to the general application of electricity to
the propulsion of vessels as well as to railway trains, he believed that
many of those present would live to see electricity applied to that
purpose, because there were so many minds now applied to the problem,
that before long he had no doubt we should see coal burned in batteries,
as it was now burned in steam boilers. The utmost they could do, then,
would be about 50 per cent. less than Admiral Selwyn said could be
accomplished with condensed fuel. He could not but wonder where Admiral
Selwyn obtained his information, knowing that a theoretically perfect
heat engine would only give 23 per cent. of the absolute heat used,
and that a pound of the best coal would give but 8,000 and hydrocarbon
13,000 heat units, while hydrogen would give 34,000; and calculating it
out, how was it possible to get out of one-sixth of a pound of carbon,
or any hydrocarbon, the amount of power stated? No doubt, when Admiral
Selwyn applied the knowledge which physicists would give him of the
amount of power which could be got out of a certain amount of carbon and
hydrogen, he would find that there was a mistake somewhere.

Mr. Reckenzaun, in reply, said it would be very difficult to answer
the question put by the Chairman, as to the cost of an electric
launch--quite as difficult as to say what would be the cost of a steam
launch. It depended on the fittings, the ornamental part, the power
required, and the time it was required to run. If such a launch were
to run constantly, two sets of accumulators would be required, one to
replace the other when discharged. This could be easily done, the floor
being made to take up, and the cells could be changed in a few minutes
with proper appliances. As to Admiral Selwyn's remarks about one-sixth
of a pound of fuel per horse power, he had never heard of such a thing
before, and should like to know more about it. Mr. Loftus Perkins'
new steam engine was a wonderful example of modern engineering. A
comparatively small engine, occupying no more space than that of a steam
launch of considerable dimensions, developed 800 horse power indicated.
From a mechanical point of view, this engine was extremely interesting;
it had four cylinders, but only one crank and one connecting rod; and
there were no dead centers. The mechanism was very beautiful, but would
require elaborate diagrams to explain. Mr. Perkins deserved the greatest
praise for it, for in it he had reduced both the weight of the engine
and the consumption of fuel to a minimum. He believed he used coke and
took one pound per horse power. He should not like to cross the Channel
in the electric launch, if there was a heavy sea on, for shaking
certainly did not increase the efficiency of the accumulators, but a
fair amount of motion they could stand, and they had run on the Thames,
by the side of heavy tug boats causing a considerable amount of swell,
without any mishap. Of course each box was provided with a lid, and the
plates were so closely packed that a fair amount of shaking would not
affect them; the only danger was the spilling of the acid. Mr. Crohne
had remarked that a torpedo boat of that size would have 100 indicated
horse power, but then the whole boat would be filled with machinery.
What might be done with electricity they had, as yet, no idea of. At
present, they could only get 33,000 foot pounds from 1 lb. of lead and
acid, though, theoretically, they ought to get 360,000 foot pounds. Iron
in its oxidation would manifest theoretically 1,900,000 foot pounds
per lb. of material. As yet they had not succeeded in making an iron
accumulator; if they could, they would get about six or seven times
the energy for the same weight of material, or could reduce the
weight proportionately for the same power, and in that way they might
eventually get 70 horse power in a boat of that size, because the weight
of the motor was not great. With regard to the formation of a film on
the surface, no doubt a film of sulphate of lead was formed if the
battery stood idle, but it did not considerably reduce its efficiency;
as soon as it was broke through by the energy being evolved from it, it
would give off its maximum current. They knew by experience that, with
properly constructed accumulators, 80 per cent. of the energy put into
them was returned in work. It was quite certain, as Mr. Crampton said,
that it would be a long time before steam was superseded: he did not
prophesy at all; and he entitled his paper "Electric Launches," because
it would be presumptuous to speak of anything more until larger vessels
had been made and tried. With regard to Mr. Gumpel's remark on the
friction of the propeller, he would say that it was constructed to run
900 revolutions; if it were driven by a steam engine, and the speed
reduced to 300, not only would the pitch have to be altered, but the
surface would have to be larger, which would entail more friction. Mr.
Crohne would bear him out that they lost only 5 per cent. by slip and
friction combined, on an average of a great number of trials, both with
and against the current.

The Chairman in proposing a vote of thanks to Mr. Reckenzaun, said he
rejoiced to find that that gentleman had proved, to one man at least,
that his views had been mistaken. He found in these days of the
practical applications of electricity, that the ideas of most practical
men were gradually being proved to be mistaken, and every day new facts
were being discovered, which led them to imagine that as yet they were
only on the shore of an enormous ocean of knowledge. It was quite
impossible to say what these electric launches would lead to. Certain
points of great importance had been pointed out; they gave great room
and they were always ready. For lifeboat and fire engine purposes, as
Captain Shaw pointed out at Vienna, this was of great consequence.

At first they were led to believe that there was great stability, but
that idea had been a little shaken, not as to the boat itself, but as
to the influence of the motion of the water upon the constancy of the
cells. But these boats were only intended for smooth water, and if
they could not be adapted for rough water, he feared Admiral Selwyn's
suggestion of the application of this principle to lifeboats would fall
to the ground; but if secondary batteries were not calculated as yet
to stand rough usage, it only required probably some thought on Mr.
Reckenzaun's part to make them available even in a gale. Enormous
strides were being made with regard to these batteries. No one present
had been a greater skeptic with regard to them at first than be himself;
but after constant experiments--employing them, as he had done for many
months, for telegraphic purposes--he was gradually coming to view them
with a much more favorable eye. The same steps which had rendered all
scientific notions practicable, had gradually eliminated the faults
which originally existed, and they were now becoming good, sound,
available instruments. At present, he could only regard this electric
launch as a luxury. He had hoped that Mr. Reckenzaun would have been
able to say something which would have enabled poor men to look forward
to the time when they might enjoy themselves in them on the river; but
he was told at Vienna, when he enjoyed two or three trips in this boat
on the Danube, that her cost would be about £800, which was a little too
much for most people. They wanted something more within their reach,
so that at various points on the river they might see small engines
constantly at work supplying energy to secondary batteries, and so that
they might start on a Friday evening, and go up as far as Oxford, or
higher, and come down again on Monday morning. He must congratulate Mr.
Reckenzaun on the excellent diagrams he had constructed. The trouble of
calculating figures of this sort was very great when making experiments;
and the use of diagrams and curves expedited the labor very much. At
present they were passing through a stage of electrical depression;
robbery had been committed on a large scale; the earnings of the poor
had been filched out of their pockets by sanguine company promotors; an
enormous amount of money had been lost, and the result had been that
confidence was, to a great extent, destroyed; but those who had been
wise enough to keep their money in their pockets, and to read the papers
read in that room, must have seen that there was a constant steady
advance in scientific knowledge of the laws of electricity and in their
practical applications, and as soon as some of these rotten, mushroom
companies had been wiped out of existence, they might hope that real
practical progress would be made, and that the day was not far distant
when the public would again acquire confidence in electrical enterprise.
They would then enable inventors and practical men to carry out their
experiments, and to put electrical matters on a proper footing.

       *       *       *       *       *




THE FIRST EXPERIMENTS WITH THE ELECTRIC LIGHT.


Electric lighting dates back, as well known; to the celebrated
experiment of Sir Humphry Davy, which took place in 1809 or 1810, but
the date of which is often given as 1813. There exist however, some
indications that experiments on the production of the electric spark
between carbons had been performed before the above named date.

Mr. S.P. Thompson has given the following interesting details in regard
to this subject: In looking over an old volume of the _Journal de
Paris_, says he, I found under date of the 22d Ventose, year X.
(March 12, 1802), the following passage, which evidently refers to an
exhibition of the electric arc:

"Citizen Robertson, the inventor of the phantasmagoria (magic lantern),
is at present performing some interesting experiments that must
doubtless advance our knowledge concerning galvanism. He has just
mounted metallic piles to the number of 2,500 zinc plates and as many of
rosette copper. We shall forthwith speak of his results, as well as of a
new experiment that he performed yesterday with two glowing carbons.

[Illustration: SIR HUMPHRY DAVY'S ELECTRIC LIGHT EXPERIMENTS IN 1813.]

"The first having been placed at the base of a column of 120 zinc and
silver elements, and the second communicating with the apex of the pile,
they gave at the moment they were united a brilliant spark of an extreme
whiteness that was seen by the entire society. Citizen Robertson will
repeat this experiment on the 25th."

The date generally given for the invention of the electric light by Sir
Humphry Davy is 1809, but previous mentions of his experiment are
found in Cuthberson's "Electricity" (1807) and in other works. In the
_Philosophical Magazine_, vol. ix., p. 219, under date of Feb. 1, 1801,
in a memoir by Mr. H. Moyes, of Edinburgh, relative to experiments made
with the pile, we find the following passage:

"When the column in question had reached the height of its power, its
sparks were seen by daylight, even when they were made to jump with a
piece of carbon held in the hand."

[Illustration: ELECTRIC LIGHTING IN PARIS IN 1844.]

In the _Journal of the Royal Institution_, vol. i. (1802), Davy
describes (p. 106) a few experiments made with the pile, and says:

"When, instead of metals, pieces of well calcined carbon were employed,
the spark was still larger and of a clear white."

On page 214 he describes and figures an apparatus for taking the
galvano-electric spark into fluid and aeriform substances. This
apparatus consisted of a glass tube open at the top, and having at the
side a tube through which passed a wire that terminated in a carbon.
Another wire, likewise terminating in carbon, traversed the bottom and
was cemented in a vertical position.

But all these indications are posterior to a letter printed in
_Nicholson's Journal_, in October, 1800, p. 150, and entitled:
"Additional Experiments on Galvanic Electricity in a Letter to Mr.
Nicholson." The letter is dated Dowry Square, Hotwells, September 22,
1800, and is signed by Humphry Davy, who at this epoch was assistant to
Dr. Beddoes at the Philosophical Institution of Bristol. It begins thus:

"Sir: The first experimenters in animal electricity remarked the
property that well calcined carbon has of conducting ordinary galvanic
action. I have found that this substance possesses the same properties
as metallic bodies for the production of the spark, when it is used for
establishing a communication between the extremities of Signor Volta's
pile."

In none of these extracts, however, do we find anything that has
reference to the properties of the arc as a continuous, luminous spark.
It was in his subsequent researches that Davy made known its properties.
It will be seen, however, that the electric light had attracted
attention before its special property of continuity had been observed.

It results from these facts that Robertson's experiment was in no wise
anterior to that of Davy. The inventor of the phantasmagoria did not
obtain the arc, properly so called, with its characteristic continuity,
but merely produced a spark between two carbons--an experiment that had
already been made known by Davy in 1800. The latter had then at his
disposal nothing but a relatively weak pile, and it is very natural
that, under such circumstances, he produced a spark without observing
its properties as a light producer.

It was only in 1808 that he was in a position to operate upon a larger
scale. At this epoch a group of men who were interested in the progress
of science subscribed the necessary funds for the construction of a
large battery designed for the laboratory of the Royal Institution. This
pile was composed of 2,000 elements mounted in two hundred porcelain
troughs, one of which is still to be seen at the Royal Institution. The
zinc plates of these elements were each of them 32 inches square, and
formed altogether a surface of 80 square meters. It was with this
powerful battery that Davy, in 1810, performed the experiment on the
voltaic arc before the members of the Royal Institution.

The carbons employed were rods of charcoal, and were rapidly used up
in burning in the air. So in order to give longer duration to his
experiment, Davy was obliged, on repeating it, to inclose the carbons in
a glass globe like that used in the apparatus called the electric egg.
The accompanying figure represents the experiment made under this form
in the great ampitheater of the Royal Institution at London.--_La
Lumiere Electrique_.

       *       *       *       *       *




ELECTRICAL GRAPNEL FOR SUBMARINE CABLES AND TORPEDO LINES.

By H. KINGSFORD.


All those who are acquainted with the cable-lifting branch of submarine
telegraphy are well aware how important a matter it is in grappling
to be certain of the instant the cable is hooked. This importance
increases, of course, with the age and consequent weakness of the
material, as the injury caused by dragging a cable along the bottom is
obviously very great.

[Illustration: ELECTRICAL GRAPNEL FOR SUBMARINE CABLES AND TORPEDO
LINES.]

It is easy also to understand the fact that in nearly all cases the most
delicate dynamometers must fail to indicate immediately the presence
of the cable on the grapnel, more especially in those cases where a
considerable amount of slack grapnel rope is paid out. In many cases,
therefore, the grapnel will travel through a cable without the
slightest indication (or at least reliable indication) occurring on the
dynamometer, and perhaps several miles beyond the line of cable will be
dragged over, either fruitlessly, or to the peril of neighboring cables;
whereas, should the engineer be advised of the cable's presence on the
grapnel, the break will probably be avoided and the cable lifted; at any
rate, the position of the cable will be an assured thing.

My own knowledge of cable grappling has convinced me of these facts; and
I am well assured that those engineers at least who have been engaged
in grappling for cables in great depths, or for weak cables in shallow
water, will heartily agree with me.

In addition to the foregoing remarks re the insufficiency of the
dynamometer as an instrument for indicating the presence of a cable on
the grapnel, I might remind engineers of the troubles and perplexities
which occur incessantly in dragging over a rocky bottom. The grapnel
hooks a rock, a large increase of strain is indicated on the
dynamometer, and it becomes doubtful whether the cable as well is hooked
or not. Again, it frequently happens in grappling over a rocky bottom
that one or more prongs are broken off, the grapnel thus becoming
useless, great waste of time being thus occasioned. Fully realizing all
the difficulties herein enumerated, it occurred to me that a grapnel
might be constructed in such a manner as to automatically signal by
electrical means the hooking of the cable, while it would ignore all
strain that external causes might bring to bear on it, and thereby
obviate the uncertainties attached to the use of the grapnels at present
in vogue. To effect this, I designed early in 1881 a grapnel fitted in
each prong with an insulated conducting surface, and a plunger and pin
so arranged that the cable, when hooked, should, by the pressure that
it would bring to bear on any of the plungers, cause the pin to come in
contact with the conducting surface, itself in electrical communication
with any suitable current detecter and battery on board the repairing
ship, and thereby complete the circuit. This grapnel was successfully
used on the Anglo-American Telegraph Company's repairing steamer Minia
in the summer of 1881.

Subsequently, in discussing the construction of the grapnel with
Captain Troot, we concluded that something was yet wanted to render
the successful working in deep water absolutely sure, and we decided,
consequently, to make certain alterations.

This improved form may be constructed, either with a contact-plate in
each prong, or with one contact-plate common to all the prongs; the
latter is somewhat simpler, and is therefore the plan that we usually
adopt. Both forms are shown in the accompanying diagrams. The form
of grapnel in Diagram No. 1 has one advantage over the other in this
respect, viz., that should a prong be ruptured so as to render it
useless, the fact would immediately be known on board. A circuit formed
in such a manner, by the breaking off of a branch lead, would have
greater resistance than that formed by the contact resulting from
pressure of cable on the plungers; this difference would be manifested
on the indicator (of low resistance) placed in circuit with the
alarm-bell, or, if any doubt remained, a Wheatstone's bridge, or simpler
still, a telephone might be made use of.

In some cases we may protect the plungers from the pressure of ooze,
etc., by guards fitted to the stem of the grapnel, but in practice we
have not found these to be necessary.

The water is allowed free access around and about each separate part, in
order that its pressure shall be equal on all sides. This arrangement
renders the grapnel as effectual in the deepest as in the shallowest
water.

By making the plungers in two pieces, with a rubber washer or its
equivalent between them, we prevent mud or ooze from getting behind and
interfering with their working. As the hole in the rubber surrounding
the contact-plate, by caused the passage of the pin through it, closes
up as soon as the pressure is removed, leaving in the rubber a fault of
exceedingly high resistance, the rubber does not require renewing.

In the rubber in which we embedded the contact-plate, we place a layer
or more of tinfoil or other easily pierced conducting surface, through
which the pin passes on its way to the contact-plate proper. This method
we have adopted in order to make the assurance of contact doubly sure.

The grapnel just described we had in use on the Minia since April last.
We have tried it severely, and have never known it to fail. No swivel
has been used with the rope, in the heart of which is the insulated
wire, as it would allow the grapnel to turn over on the bottom, and
would be apt to twist and break the wire short off. As a matter of
fact, the grapnel will turn, and does turn, with the rope; a swivel is
therefore of no value. We are perfectly awake, however, to the fact that
a grappling-rope should be made in a manner that will not allow it to
kink; and engineers should avail themselves of such rope, especially in
deep water. Patents have lately been granted to Messrs. Trott &
Hamilton for the invention of a form of rope or cable answering all the
requirements of this work.

A small type of grapnel fitted in the manner I have described may be
very advantageously used for searching purposes, to ascertain the
position either of telegraph or torpedo lines; by towing at a quick rate
much time may be saved. The position being ascertained, if it be not
desired to lift the cable, the grapnel can be released and hove on board
by a tripping line, which can always be attached when such work is
contemplated. The great importance of being able to localize an enemy's
torpedo lines without raising an alarm will be readily seen by engineers
engaged in torpedo work.


REFERENCES TO THE DIAGRAMS.

a, stem of the grapnel containing core; b, flukes; c, recess for
insulated contact-plate connected to core; d, covering plate screwed on
bottom of grapnel; e, button of plug; f, rubber washer and button; g,
metal-plate; h, stem of plug, on which in the under counter-sink, U is
a small metal disk which prevents the fittings from fallings out; i,
needle; j, spring; k, counter-sink for head of plug; l, counter-sink for
spring.

       *       *       *       *       *




HUGHES' NEW MAGNETIC BALANCE.


A new magnetic balance has been described before the Royal Society
by Prof. D. E. Hughes, F.R.S., which he has devised in the course of
carrying out his researches on the differences between different kinds
of iron and steel. The instrument is thus described in the _Proceedings
of the Royal Society_:

"It consists of a delicate silk-fiber-suspended magnetic needle, 5 cm.
in length, its pointer resting near an index having a single fine black
line or mark for its zero, the movement of the needle on the other
side of zero being limited to 5 mm. by means of two ivory stops or
projections.

[Illustration]

When the north end of the needle and its index zero are north, the
needle rests at its index zero, but the slightest external influence,
such as a piece of iron 1 mm. in diameter 10 cm. distant, deflects the
needle to the right or left according to the polarity of its magnetism,
and with a force proportional to its power. If we place on the opposite
side of the needle at the same distance a wire possessing similar
polarity and force, the two are equal, and the needle returns to zero;
and if we know the magnetic value required to produce a balance, we know
the value of both. In order to balance any wire or piece of iron placed
in a position east and west, a magnetic compensator is used, consisting
of a powerful bar magnet free to revolve upon a central pivot placed
at a distance of 30 or more cm., so as to be able to obtain delicate
observations. This turns upon an index, the degrees of which are
marked for equal degrees of magnetic action upon the needle. A coil of
insulated wire, through which a feeble electric current is passing,
magnetizes the piece of iron under observation, but, as the coil itself
would act upon the needle, this is balanced by an equal and opposing
coil on the opposite side, and we are thus enabled to observe the
magnetism due to the iron alone. A reversing key, resistance coils, and
a Daniell cell are required."

The general design of the instrument, as shown in a somewhat crude form
when first exhibited, is given in the figure, where A is the magnetizing
coil within which the sample of iron or steel wire to be tested is
placed, B the suspended needle, C the compensating coil, and M the
magnet used as a compensator, having a scale beneath it divided into
quarter degrees.

The idea of employing a magnet as compensator in a magnetic balance is
not new, this disposition having been used by Prof. Von Feilitzsch in
1856 in his researches on the magnetizing influence of the current. In
Von Feilitzsch's balance, however, the compensating magnet was placed
end on to the needle, and its directive action was diminished at will,
not by turning it round on its center, but by shifting it to a greater
distance along a linear scale below it. The form now given by Hughes to
the balance is one of so great compactness and convenience that it
will probably prove a most acceptable addition to the resources of the
physical laboratory.--_Nature_.

       *       *       *       *       *




HOW TO HARDEN CAST IRON.


Cast iron may be hardened as follows: Heat the iron to a cherry red,
then sprinkle on it cyanide of potassium and heat to a little above red,
then dip. The end of a rod that had been treated in this way could not
be cut with a file. Upon breaking off a piece about one-half an inch
long, it was found that the hardening had penetrated to the interior,
upon which the file made no more impression than upon the surface. The
same salt may be used to caseharden wrought iron.

       *       *       *       *       *




APPARATUS FOR MEASURING SMALL RESISTANCES.


The accompanying engraving shows a form of Thomson's double bridge, as
modified by Kirchhoff and Hausemann. The chief advantage claimed for
this instrument consists in the fact that all resistances of defective
contact between the piece to be measured and the battery are entirely
eliminated--an object of prime importance in measuring very small
resistances. By the use of this instrument resistances can be measured
accurately down to one-millionth of a Siemens unit.

The general arrangement of the instrument is shown in Fig. 1; Fig. 2
being a diagram of the electrical connections.

[Illustration: FIG. 1.--KIRCHHOFF AND HANSEMANN'S BRIDGE FOR MEASURING
SMALL RESISTANCES.]

The piece of metal to be measured, M, is placed in the measuring forks,
gg, in such a manner that the movable fork is removed as far as possible
from the stationary one; if the weight of the piece be insufficient to
secure a good connection, additional weights may be placed upon it. The
main circuit includes the battery, B (Fig. 2), consisting of from two to
four Bunsen cells, the key, T, the German silver measuring wire, N, and
the piece of metal resting on the forks, all being joined in series. The
German silver wire, N, is traversed by two movable knife-edge contacts,
cc, as shown. Connections are made between these contacts, cc, the
resistance box, the prongs, k and l, of the forks, gg, and the
reflecting galvanometer, as shown in Fig. 2. A resistance of ten units
is inserted at o and n, while at m and p twenty units or one thousand
units are inserted. The positions of cc are then varied until the
galvanometer shows no deflection when the key, T, is depressed.

[Illustration: FIG. 2.--DIAGRAM SHOWING ELECTTRICAL CONNECTIONS OF
BRIDGE.]

When such is the case, the ratio of resistances n/m is equal to o/p;
letting M equal the resistance of the metal bar between the points, h
and i, and N equal to the resistance between the points, cc, on the
measuring wire, N, then we shall have

M = N (n/m) = N (o/p).

Knowing the cross section in millimeters, Q, of the bar, and observing
the temperature, t, in degrees Centigrade, its conductivity, x, as
compared with mercury can be determined. If L be the distance, h l or k
i, in meters, then

x = (1/m) (L/Q) (1 + at).

For pure metals the value of a may be taken at 0.004; but alloys have a
different coefficient. The instrument is made by Siemens and Halske,
and is accompanied by a table giving resistances per millimeter of the
measuring wire, N.--_Zeitsch. für Elektrotechnik_.

       *       *       *       *       *




TERRESTRIAL MAGNETISM.

[Footnote: For a full account of experiments relating to magnetism on
railways in New York city, see SCIENTIFIC AMERICAN, January 19,1884.]


_To the Editor of the Scientific American_:

An item has appeared recently in several papers, stating that New York
is a highly magnetized city--that the elevated railroad, Brooklyn Bridge
cables, etc., are all highly magnetized. As this might convey to the
general reader the impression that the magnetism thus exhibited was
peculiar to New York city, and as many of your subscribers look
anxiously for your answers to numerous questions put for the elucidation
of apparent, scientific mysteries, I have thought that perhaps a
statement in plain language of experiments made at various times, to
elucidate this subject, might, in conjunction with a diagram, serve to
explain even to those who have not made a special study of science a few
of the interesting phenomena connected with


TERRESTRIAL MAGNETISM.

Some of the first experiments I made, while professor at the Indiana
State University, were detailed in the March and August numbers,
1872, of the _Journal_ of the Franklin Institute, and I think showed
conclusively that the earth, by induction, renders all articles of iron,
steel, or tinned iron magnetic; possessing for the time being polarity,
after they have been in a settled position for a short time.

In Dr. I. C. Draper's "Year Book of Nature" for 1873, mention is made
of the experiments in which I found every rail of a N. and S. railroad
exhibiting polarity.

The same statements were repeated in one of a series of articles sent by
me to the _Indianapolis Daily Journal_, dated Jan. 20, 1877, in which I
used the following language:

"Every article of iron or steel or tinned iron, by the earth's
induction, becomes magnetic. Thus, if we examine our stoves, or a
doorlock, or long vertical hinge, or even a high tin cup, by holding a
delicate magnetic needle in the hand near those objects, we find the
earth has, by induction, attracted to the lower end of the stove
utensils, etc., the opposite magnetism from its own; and repelled to the
upper end of the stove, etc., the same magnetism which exists in our
northern hemisphere. Consequently, the bottom of the stove, or of the
hinge, cup, etc., will attract the south (or unmarked end) of our
needle; while the top of the stove, etc., attracts the north, or marked
end of our magnetic needle. If we apply our needle to the T rails of a
N. and S. railroad, we not only find that the lower flange of the rail
attracts the S. end of our needle, while the upper flange attracts the
N. end of our needle, but we also find, where the two rails come nearly
together (say within two inches), that the N. end of the rail attracts
the S. end of our needle, while the S. end of the rail attracts the N.
(or marked) end of our magnetic needle."

[Illustration: MAGNETISM ON RAILWAYS.]

Quite recently, being anxious to see the effect produced on the needle
by rails laid E. and W., I experimented on some recently laid here;
starting from a S. terminus, in the town of New Harmony, and gradually
curving northeast, until the road pursues a due east course to
Evansville. There is, however, a branch road of about half a mile, which
starts from the Wabash River, at a _west_ terminus, and runs due east
to join the other, near where that main track commences its northeast
curve. The results (more readily understood by an inspection of the
diagram) were as follows:

1. At the south terminus of the railroad, the rails on the east side of
the track as well as those on the west side attracted at their south
ends the marked end of a small magnetic needle, both at the upper and
lower flange; the usual vertical induction being in this case overcome
by the greater lateral induction. Whenever, on progressing north, the
rails were at least about two inches apart, the upper flange of the
north end of any rail would attract the unmarked, while the south end
of its neighbor or any other of the north and south laid rails would
attract the marked end.

2. The same results were obtained from rails laid all around the
northeast curve, and even after they had acquired a due west to east
course; showing that each rail acquired the same magnetic polarity which
would be exhibited by any magnetic needle oscillating freely in our
northern hemisphere, dipping also at its north end considerably downward
if suspended at its center of gravity.

3. Applying the needle at the _west_ terminus, a few anomalies were
observed; but, especially nearer the junction, the rails all gave the
normal result found on the main track.

4. The wheels of the cars standing on the north and south track followed
the same law, exhibiting both vertical and lateral induction, so that
the lower rims and the forward or north part of the periphery attracted
the unmarked end of the needle, while the upper and rear, or south
portions of the periphery of the wheel attracted the marked end.

5. The wheels of cars standing on the east and west road exhibited
the following modification. The lowest rim of all the wheels, whether
standing on the _north_ rails or on the _south_ rails of said track,
in consequence of vertical induction attracted the unmarked end of the
needle, and the upper rims attracted the marked end of the needle; but
the middle portions of the periphery, both anterior and posterior, of
the wheels standing on the north rail, attracted the unmarked end, while
similar middle portions of wheels standing on south rails attracted the
marked end; in consequence of horizontal induction, the wheels being
connected by iron axles, and thus presenting considerable extension
_across_ the track, viz., from south to north.

Magnetite seems to have acquired its polarity in the same manner,
namely by the earth's induction, when the ore contains a large enough
percentage of pure iron. A large specimen (6 in. long by 3½ deep and
weighing 5½ lb.) which I obtained from near Pilot Knob, Missouri,
exhibits polarity, not only at its lateral ends, but also vertically,
as the lower surface attracts the unmarked end of a needle, while the
plane, which evidently occupied the upper surface in its native bed,
attracts the marked end of the needle.

Iron fences invariably exhibit only the polarity by vertical induction;
so also small buckets, bells, etc. But in the case of a bell about 3 ft.
in diameter at its base, and over two feet deep, tapering to about a
foot in diameter at the top, I found that although the top attracted the
marked end of the needle, the bottom attracted the unmarked end of the
needle only around the northerly half of the circumference, while
the southern portion of this lower rim attracted the marked end in
consequence of lateral induction, as in N. and S. rails.

Thus, upon a comparison of all these facts, it would appear that, if
the magnetism induced by the earth is due to so-called currents of
electricity, those currents must be _underneath_ the rails, and must
move from west to east, under the south to north rails, and from south
to north under the west to east laid rails, as indicated by the arrows
in the diagram.

This accords perfectly with what we should theoretically expect, in our
northern hemisphere, if the electricity in the earth's crust is due to
thermo-electrical currents from east to west, namely, from the more
heated to the less heated portion, on any given latitude, while the
earth revolves from west to east; as well as also from electrical
currents trending from tropical to Arctic regions.

As the network of iron rails spreads from year to year more extensively
over our continent, it will be interesting to observe whether or not
any effect is produced, meteorological, agricultural, etc., by this
diffusion of magnetism.

It may further interest some of your readers to have attention called to
facts indicating


SYNCHRONOUS SEISMOLOGY.

The year recently closed furnishes interesting corroborative testimony
of an apparent law regarding the propagation of earthquake movements
_most readily_ along great circles of our globe, as well as evidence
that these seismic movements are frequently transmitted along belts
(approximating to great circles) coincident sometimes with continental
trends, at other times with fissures which emanate in radii at every
30°, around the pole of the land hemisphere in Switzerland, as described
in one of my papers, read at the Montreal meeting of the A.A.A.S.

The terms synchronism or synchronous, as here used, are not designed to
imply absolute simultaneity (although that is sometimes the case with
disturbances 180° apart), but are rather intended to indicate the
tendency presented by these phenomena to exhibit this internal activity,
during successive days, weeks, or even months, along a given great
circle of the earth, especially one or more of those connected with the
land center; perhaps most of all along the great circle which forms the
prime vertical, when the center of land is placed at the zenith.

In order to test the above, let us examine the record of the most
prominent earthquakes or volcanic eruptions for the year 1883.

Late in Dec., 1882, and early in Feb., 1883, shocks occurred in New
Hampshire; on Jan. 11, 1883, also at Cairo, Illinois, and about the same
time at Paducah, Ky.; Feb. 27 at Norwich, Conn., and early in Feb. at
Murcia, Spain.

These, by examination of any good globe, will be found on a belt forming
one and the same great circle of the earth.

Late in March and during part of April the volcano of Ometeke in Lake
Nicaragua was active (after being long dormant); Panama, portions of
the U.S. of Colombia, and of Chili; also, in May, Helena, M.T.; and,
in June, Quito (with Cotopaxi active) were all more or less shaken by
earthquakes; and are all found on one belt of a great circle.

The principal record for the remainder of the year comprised:

An earthquake at Tabreez in North Persia, early in May, 1883.

The awful destruction in Ischia, July 29 (with Vesuvius active).

The fearful eruption in the Straits of Sunda, 25th Aug. and later.

Shocks in Sumatra and at Guayaquil, about same date or early in Sept.

Shocks at Dusseldorf, according to a Berlin paper of 5th Sept.

Shocks at Santa Barbara and Los Angeles, early in Sept.

Shocks at Gibraltar and Anatolia in October.

Shocks at Malta, Trieste, and Asia Minor in October.

Azram shaken late in Sept., and great destruction between Scios and
Smyrna.

Lastly, the formation of a new island in the Aleutian Archipelago. Date
of outburst, early in October, 1883.

Besides these, there were several other less severe disturbances, the
records of which are chiefly obtained from Nature, and which will-be
referred to below.

If the globe be so placed as to have the land center at the zenith, the
exact position of the new island, near Unnok, will be found under the
brazen meridian, while Agram, Tabreez, Sunda, Sumatra, Quito, and
Guayaquil are all on the prime vertical.

Vesuvius and Hecla were both active early in the year, and they, with
the ever restless Stromboli, are situated on the great circle which
forms with the land center at Mount Rosa, the radius running S. 30° E.,
and which would embrace the chief disturbances up to the middle of the
year, including as we go north Malta, Sicily, Rome, region of the Po,
Bologna, and in the Western Continent, after passing Hecla, Helena in
Montana Territory, reaching in Washington Territory and Oregon the belt
of it. American volcanoes: Mounts Baker, Rainier, St. Helens, Hood, and
Shasta.

Still another seismic belt, starting from the ever active Fogo, and
passing through Teneriffe (at that time erupted), would include the
regions disturbed in Oct. and Nov., namely, Cadiz, Gibraltar, Malaga
(Murcia and Valencia somewhat earlier); it then traversed the center of
land, caused the earthquakes at Olmutz in Moravia, and even tremors felt
at Irkutsk, as the seismic war moved along said great circle to the
volcanic region of S. Japan.

Again, the belt which covers the meridian of land center (about 8°-10°
E. long) covers also the region of a disturbanced area in Norway, as
well as that portion of Algeria, viz., Bona, in which a mountain 800
meters high, Naiba, is gradually sinking out of sight. About 100 geo.
miles E. of Bona is where Graham's Island appeared in the Mediterranean,
and a few months later disappeared in deep water.

Another highly seismic belt extends from the volcanoes of Bourbon, N.
Madagascar, and Abyssinia to Santoria and the oft disturbed Scios,
Smyrna, and Anatolia region; and along the same great circle were shaken
Patra in Greece on the 14th Nov., and Bosnia on the 15th; while shocks
had been felt at Trieste and Mülhouse about the 11th, and at Styria on
the 7th, and disturbances at Dusseldorf in Sept. Finally, on the 28th
Dec. S. Hungary (near the confluence of the Drave with the Danube) was
visited by seismic movements along this same great circle, which passes
through the extinct volcanic region of the Eifel, the oft shaken Comrie
in Perthshire, Scotland, the volcanic Iceland, our National Park with
its thousands of geysers, the cataclysmic region of Salt Lake and the
Wahsatch Mountains (so graphically described by the geologists of the
U.S. Geol. Survey), giving rise in Sept. to the earthquakes of Los
Angeles and Santa Barbara, and finally reaching the volcanic islands of
the Marquesas group.

Thus the seismic efforts of 1883 may be seen to have expended their
force partly along the great backbone of the S. and N. American
Cordillera, but more especially from the center of land E. and W. along
its prime vertical from Sunda to Quito, also southwesterly by the E.
coast of Spain, as well as due S. through Algeria, and S. 30° E. through
Rome, Naples, Sicily, etc. Finally, the autumnal catastrophes at and
near Scios, Anatolia, etc., seem to have been caused by a seismic wave,
propagated along the great circle, which often agitates Janina, and
produces earthquakes at Agram, where this great circle crosses the prime
vertical.

RICHARD OWEN.

New Harmony, Ind., 27 Feb., 1884.

       *       *       *       *       *




THE IRON INDUSTRY IN BRAZIL

(PROVINCE OF MINAS GERAES.)

By Prof. P. FERRAND.


Up to the present time, the methods employed in the province of Minas
Geraes (Brazil) for obtaining iron permit of manufacturing it direct
from the ore without the intervening process of casting. These methods
are two in number:

1. The _method by cadinhes_ (crucibles), which is the simpler and
requires but little manipulation, but permits of the production of but a
small quantity of metal at a time.

2. The _Italian method_, a variation of the Catalan, which requires
more skill on the part of the workmen and yields more iron than the
preceding.

As these methods seem to me of interest, from the standpoint of their
simplicity and easy installation, I propose to describe them briefly, in
order to give as faithful and general an _aperçu_ as possible of their
application. At present I shall deal with the first one only, the one
called the method by _Cadinhes_.


STUDY OF THE METHOD BY CADINHES.

The province of Minas Geraes ocupies a vast extent in the empire
of Brazil, its superficies being about 900,000 square kilometers,
representing nearly a third of the total surface.

The population is relatively small and is disseminated throughout a much
broken country, where the means of communication are very few. So it is
necessary to succeed in producing what iron is needed by means that are
simple and that require but quickly erected works built of such material
as may be at hand. The iron ore is found in very great abundance in this
region and is very easily mined.

In the center of a mass of quartzites that seem lo constitute the upper
level of the eruptive grounds of the province, there are found strata of
an ore of iron designated as _itabirite_--a mixture of oxide of iron and
quartz. These strata are of great thickness, and have numerous outcrops
that permit of their being worked by quarrying.

These itabirites present themselves under two very distinct aspects and
offer a certain difference in their composition. Some are essentially
friable, and are called by the vulgar name of _jacutingaes_. It is
this variety (which is the one most easily mined) that is principally
consumed in the forges. The others, on the contrary, are compact.
Their exploitation is more difficult, and before putting them into the
furnaces it is necessary to submit them to breakage and screening; so
the use of them is more limited.

The first variety contains less iron and more gangue, but, _per contra_,
possesses much oxide of manganese. The second, on the contrary, is
formed almost wholly of oxide of iron with but little gangue and only
traces of oxide of manganese. The following are analyses of these two
varieties of ore:

  _Friable Ore_.

  Fe_{2}O_{2}.................................. 84.9
  Oxide of manganese...........................  9.2
  Water........................................  1.9
  Quartz.......................................  4.1
                                                ----
                                               100.1

  _Compact Ore_.

  Fe_{2}O_{3} and traces of manganese.......... 99.6
  Quartz.......................................  1.1
                                                ----
                                               100.7

_Situation of the Forges_.--A forge is usually placed on the bank of
a brook, or rather of a torrent, which supplies the fall of water
necessary for the motive power by means of a flume about a hundred
meters in length. In most cases the forge is surrounded on all sides
with a forest which yields the wood necessary for the manufacture of the
charcoal, and is in the vicinity of the iron quarry, so as to reduce the
expense of hauling the ore as much as possible. The neighboring
rocks furnish the foundation stones and stones for the furnaces; the
decomposed schist gives the cement and refractory coating, and the
forest provides the wood necessary for the construction of the road,
sheds, etc. The head of the trip hammer, the anvils, and the tools are
the only objects that it is necessary to procure, and even these
the master of the forge often manufactures in part, after beginning
production with an incomplete set.

[Illustration: 7a FIG 1.--FOUR-CRUCIBLE FURNACE AND FORGE; (PLAN).]

_General Arrangement of a Forge_.--A forge usually consists of one or
two furnaces of three or four crucibles (the one shown in plan in Fig.
1 has only one four crucible furnace, A); 1 or 2 two fire reheating
furnaces, B; 1 trip hammer, C, actuated by a hydraulic wheel, D;
2 tromps which drive the wind, one of them, E, into the cadinhes
(crucibles), and the other, F, into the reheating furnace; 2 anvils,
G and H, placed near the furnace, for working delicate pieces; and
finally, the different tools that serve for maneuvering the bloom and
finishing the bars. The charcoal is preserved from rain under a shed, l.
The ore, which is brought in as needed, is dumped in a pile at M, in
the vicinity of the crucibles. The buildings are set back against the
mountain, and the water is led in by a double flume, L and N, made of
planks, and empties on one side into the wheel and into the tromp, F,
and on the other into the tromp, E, and then runs into a double waste
channel, P and Q, which carries it to the stream.

[Illustration: FIG 2.--FOUR-CRUCIBLE FURNACE; (PLAN).]

_Four Crucible Furnace_ (Fig. 2).--The arrangement of a furnace is very
simple. It consists of a cube of masonry containing several cylindrical
apertures with elliptic bases, whose large axis is paralleled with the
smaller side of the masonry. This form recalls that of a crucible;
and these cavities are, moreover, so named. In the front part of each
cadinhe there is a rectangular aperture that gives access to the bottom
of the crucible and facilitates the removal of the bloom therefrom. At
the back part there is a small aperture for the introduction of the
tuyere, and which permits, besides, of the nozzle of the latter being
easily got at so as to see whether the blast is working properly.

The sides of the crucibles are covered with a thin layer of refractory
clay, and their bottoms have a spherical concavity to hold the bloom.
The tuyere, which is fitted to a wooden conduit of square section
that runs along the back of the masonry, is placed in the axis of the
cadinhes and enters the masonry at a few centimeters from the bottom
in such away that its nozzle comes just flush with the surface of the
refractory lining. This arrangement prevents the tuyere from getting
befouled by scoriæ during the operation of the furnace and thus
interfering with the wind.

_Tromp_.--The tromp which furnishes the necessary wind to the cadinhes
consists of a hollow wooden conduit, a (Fig. 3), of square section,
which enters a chamber, b, along a length of 0.1 m. This conduit, which
is about 7 meters in height, receives the water from the flume through
the intermedium of an ajutage of pyramidal form, which serves to choke
the vein of liquid, and the extremity of which is at a few centimeters
from the conduit in order to facilitate the entrance of the air; the
latter being attracted by an ill defined action that is supposed to
be due to its being carried along by the water, and to a depression
produced by choking the flow of the liquid.

[Illustration: FIG. 3.--THE TROMP.]

Since the air that is sucked in during the operation has constantly same
pressure, there is no valve for regulating the entrance of the water
into the vertical conduit. Upon issuing from the latter, the mixture of
air and water strikes the surface of the water in the chamber, b,
and the violence of the shock upon the bottom is deadened by the
interposition of a stone. While the water is escaping through a lateral
aperture in the chamber, b, the air is reaching the tuyeres through a
wooden conduit of square section which is fitted to an aperture in the
upper part of the chamber. This sorry arrangement, which obliges the
mixture of air and water to penetrate the water at the bottom of the
upright conduit, a, retards the separation of the two fluids, and
results in damp air being forced into the crucibles.

_The Trip Hammer_.--Fig. 4 shows the general arrangement of the
apparatus that go to make up the forging mill. The hammer and cam shaft
have their axes parallel, and the latter is placed in the prolongation
of the axis of the wheel. The hammer consists of a roughly squared beam,
4 meters in length, and of 0.25 m. section. The head, A, consists of a
mass of iron weighing 150 kilos, including the weight of the straps
that surround the beam on every side of the piece of iron. The axis of
rotation is situated at the other extremity of the beam, B. The cam
shaft which serves to maneuver the trip hammer is provided with four
cams which lift the beam at a point near the hammer. The length of this
shaft (to the extremity of which is adapted the water wheel) is 4.75 m.,
and its diameter is 0.50 m. The wheel is an _overshot_ one, 3.25 m. in
diameter by 1 m. in width. The water, which is led to it by a flume,
acts upon it by its weight and impact, and is retained in the buckets
and kept from overshooting the mark by a jacket made of planks.

[Illustration: FIG. 4.--THE TRIP HAMMER.]

The anvil upon which the hammer strikes is surrounded by a bed of stones
(quartzites) derived from the neighboring rocks. It is a mass of iron,
75 kilogrammes in weight. In order to prevent vibrations in the trip
hammer when it is lifted, and increase the number of blows, there is
established a spring beam, which is formed of unsquared timber, which
is firmly fastened at one of its extremities, and which receives at the
other end the shock of the hammer head when the latter reaches the end
of its upward travel.

_Reheating Furnace_.--This is a double fire furnace, like those used in
our smithies, except that the wind, instead of being forced into it by
means of a bellows, is supplied by a tromp which receives water from the
same channel as the wheel. The two furnace tuyeres are arranged exactly
like those of the cadinhes, upon a wooden conduit which starts from the
wind chamber (Fig. 5). This furnace serves to prevent the cooling of
such blooms as are awaiting their turn to be shingled, and of such bars
of finished iron as are being made into tools.


OPERATION OF THE SYSTEM.

A forge like the one whose plan we give, may be run with 1 workman at
the cadinhes, 1 assistant, 1 workman at the hammer; total, 3 men.

_Furnace_.--The work lasts about twelve hours per day, and three
operations of three to four hours are performed in each cadinhe, thus
making twelve per day. At each operation, 22.5 kilos. of ore and 45 of
charcoal are used. From this there is obtained a bloom of 15 kilos. The
operation is performed as follows:

While the assistant has gone to put the bloom of the preceding operation
under the hammer, the workman prepares at the bottom of the crucible a
bed consisting of a mixture of sand and very fine charcoal, and then
fills the crucible up to its edge with charcoal. At the end of a quarter
of an hour, the fuel being thoroughly aglow, the workman puts in the
first charge of ore in powder (_jacutingue_), about 2 kilos, and covers
it with charcoal.

Starting from this moment, he goes on charging every five or ten minutes
with 1.5 to 2 kilos of ore, taking care in doing so to keep the crucible
stuffed with charcoal, which the assistant places in piles around each
cadinhe. This lasts about two and one-half hours. At the end of this
time he stops putting in charcoal, and standing upon the masonry, walks
from one cadinhe to another, carrying a large rod, in order to study the
lay of the bloom. Then, the fire being entirely out, he scrapes out the
bed of sand and charcoal that closes the opening in the bottom of the
crucible, removes the mass of ferruginous scoriæ which forms a hard
paste and surrounds the bloom, and takes this latter out by means of a
hook.

The workman runs the four cadinhes at once, this being easily enough
done, since he has neither to bother himself with regulating the wind,
which enters always with the same pressure, nor with the flow of the
scoriæ, which remain always at the bottom of the crucible. His role
consists simply in keeping his fires running properly, being guided in
this by the color of the flame without making an examination in the
interior. He draws each of the four blooms out from its bed at the end
of the operation, while the assistant carries the first to the hammer
and the three others to the reheating furnace. He afterward cleans
out the crucible, prepares the bed of sand and charcoal, fills with
charcoal, and then passes to the next, and so on.

[Illustration: FIG. 5.--REHEATING FURNACE.]

_Trip Hammer_.--The workman at the hammer takes the bloom from the hands
of the assistant and shingles it under the head. Then he begins to give
it shape, bringing it to the state shown at c, in Fig. 7. The assistant
then brings him another bloom and takes the one that has been shingled
to the reheating furnace, where he heats but one of its extremities.
When the four blooms have been shingled, the workman takes up the first
and begins to draw out one of its extremities, which he afterward cools
in water and uses as a handle for finishing the work, d. Then he reheats
the other extremity, and, after drawing it out as he did the other,
obtains a bar of finished iron which he doubles, as shown at e, to thus
deliver to the trade.

[Illustration: FIG. 6.--CADINHE IN OPERATION.]

One of these bars weighs from 11 to 12 kilogrammes. It will be seen
that, during the course of the work, the furnace workmen and the hammer
workmen have well defined duties to perform; but it is not the same with
the assistant, who goes from one to the other according to requirements.
There are, however, some forges in which each of the workmen has an
assistant, since the blooms produced are heavier, and one assistant
would not suffice for the work of the two men. In such a case the
assistant at the crucibles carries the blooms to the reheating furnace,
and the assistant at the hammer carries them from thence to the hammer.

[Illustration: FIG. 7.--WORKING THE BLOOM.]


ELABORATION OF THE ORE.

We have seen that the workman who has charge of the fire contents
himself with putting charcoal and ore alternately into the crucibles,
and that too according to the aspect of the flames, without making any
examination in the interior, in order to judge whether the work is
proceeding well. The bloom forms gradually beneath the nozzle of the
tuyere, in the center of the bed of sand and charcoal, and is surrounded
on every side with an exceedingly pasty mass, formed of silicates of
iron and manganese (Fig. 7). It is only at the end of the operation that
the workman, by means of a rod, causes the burning coal to drop and
verifies the proper position of the bloom by breaking the layer of
scoriæ that surrounds it. This coating he breaks off, removes the bloom
with a hook, and agglutinates with his rod the different bubbles that it
exhibits, and the assistant then carries it to the hammer.


SETTING UP A FORGE.--SELLING PRICE OF THE IRON.

To set up a forge like the one we have described, it is necessary to
count upon a first cost of about 10,000 francs. Add to this the cost of
50 hectares of forest to furnish the charcoal that the workmen have to
make every day. The cost of this is very variable, and floats between
2,500 and 5,000 francs per 100 hectares. The cost the ore is only that
connected with getting it but and hauling it.

_Manual Labor_.--The charcoal burners receive 1.25 francs per load of 90
kilos, thus bringing the price of the product (including cost price of
forest) at 2.4 francs per 100 kilos. The workmen in the furnace are paid
at the rate of from 2.50 to 3.75 francs per day. Those that work the
hammers receive 3.75 francs, and the assistants 1.25 francs.

_Carriage of the Forged Iron_.--The iron is carried from the forge
to the places of consumption on the backs of mules, and the cost of
carriage is, on an average, 0.25 franc per 100 kilos and per kilometer.

_Selling Price_.--The selling price is very variable, and depends
principally upon the distance of the place where sold from the different
forges that surround it. At Ouro Preto the price varies between 45 and
50 francs per 100 kilos.

The following is a _resume_ of the data which precede:

Cost of first establishment.................. 10,000 fr.
Charcoal per kilogramme......................   2.40
                      { Furnace men.... 2.50 to 3.75
Manual labor per day  { Hammer men............. 3.75
                      { Assistants............. 1.25
Carriage of forged iron per kilometric ton..... 2.50
Selling price per 100 kilos................ 45 to 50

--_Le Genie Civil_.

       *       *       *       *       *




THE STEAMER CHURCHILL.


We give engravings of the Churchill, a vessel lately built to the order
of Mr. Walter Peace, London agent to the Natal Harbor Board, by Messrs.
Hall, Russell, and Co., Aberdeen. She was designed by Mr. J.F. Flannery,
consulting engineer to the Board, for special service at Natal. The
Churchill has been constructed so as to be capable of towing into or out
of harbor over the bar in any weather, of acting as a very powerful fire
engine, of carrying a large amount of fresh water for the use of other
ships, of landing troops from transports which the harbor is too shallow
to admit, of recovering lost anchors and cables, of which there are a
large number off the coast, and of acting in time of need as a torpedo
or coast defense vessel; she was launched on the 16th August, and is
likely to fulfill all these requirements.

[Illustration: THE NEW STEAMSHIP CHURCHILL.]

The principal dimensions of the vessel are: Length between
perpendiculars 115 feet, breadth, extreme, 22 feet, depth of hold 11
feet, and maximum draught with full bunkers 7 feet 6 inches. There are
four water-tight iron bulkheads forming five compartments; the stern is
built very full to protect the propellers. Accommodation is arranged on
deck for the captain aft with two spare berths, mate and two engineers
amidships, while six white hands will occupy the forward forecastle, and
six Kaffirs the after one. For towing purposes she is fitted with one
main and two skip hooks secured to the main framing; towing rails are
placed aft, while bitts are put on one each quarter, will be seen by
referring to the deck plan.

The vessel is propelled by twin screws 6 feet 8 inches in diameter and
13 feet 6 inches pitch; these are of cast iron, have four blades, and
are driven by a double pair of compound inverted direct acting engines
(see Figs. 4 to 7) which are capable of developing 600 indicated horse
power, and whose cylinders are 19 inches and 34 inches in diameter with
a stroke of 2 feet. The condensers form part of the engine frame, and
have guide faces cast on for the crosshead shoes. They are fitted with
gun metal tube-plates, and each contain 516 tubes, 3/4 inch in diameter,
which have an exposed length of 6 feet 5 inches, and give a total
cooling surface of 650 square feet. The air and circulating pumps are
bolted to the back of the condensers, and are worked by levers from the
engine crosshead. Each engine has one feed and one bilge pump attached
to the air pump, and worked by the same lever. The plan of the engines
shows the pump arrangement very completely.

[Illustration: ENGINES AND BOILERS OF THE NEW STEAMSHIP CHURCHILL.]

The steam is supplied by two circular return tube boilers, 9 feet 6
inches in diameter and 10 feet long, with two furnaces in each. The
boilers, which are of steel throughout, except the tubes, are placed
longitudinally, and are fitted with two pairs of the Martyn-Roberts
patent safety valves. They have one steam dome between them. The total
heating surface is 1,700 square feet, the total steam space is 330 cubic
feet, and the working pressure 100 lb. per square inch.

The fire pump is a Wilson's "Excelsior," with 10 inch steam cylinder and
8 inch water barrel. This powerful pump is in a special compartment of
the fore hold, and will draw water from the bilge, sea, or either hold.
A steam windlass and a double-handle winch are on deck as shown. On
trial trip the engines of the Churchill indicated a maximum of 645.5
horse power, driving the vessel 10.495 knots per hour. The vessel is
remarkable for diversity of uses, for heavy engine power in a small
hull, and for general compactness of arrangement.--_Engineering_.

       *       *       *       *       *




THREE-WAY TUNNELS.


Mr. T.R. Cramton, who at the Southampton meeting of the British
Association suggested a method of tunneling which, under certain
conditions, seems of excellent promise, brought forward a suggestion at
Southport for the construction of three-way tunnels. Now, the undoubted
aim of all engineers is economy of construction and the securing of
permanent advantages. Mr. Crampton maintains that the suggested system
will give these, that three tunnels of, say, 17 ft. diameter, can be
constructed cheaper than one of 30 ft. diameter. After describing Sir J.
C. Hawkshaw's scheme for the ventilation of long tunnels, the three-way
scheme was discussed. Three separate tunnels of 17 ft. diameter each,
or 227 ft. area, are to be connected by large passages about midway
of their length. These passages are without valves; in fact, free air
passages. Between these midway connections and the ends, say again
midway between, is formed a branch at right angles either above or below
with separate openings from the branch into the other tunnels, such
openings being provided with doors or valves quite clear of the main
tunnel, any two of which may be closed, thus separating at this point
the corresponding tunnels from the third. The branch is to be led to any
convenient position where the exhustion apparatus can be placed. If two
of the tunnels are left open to this branch, and the third one shut off
from it by closing the doors, the vitiated air will be drawn from the
two working tunnels, through the connecting branch, while fresh air will
be partly sucked down the vertical shafts through their open ends and
partly at the center tunnel, which is supplied by forcing air down the
vertical shaft in communication with it, a stop or door being placed
just outside of the bottom of the shaft so as to compel the air to flow
to the center of the tunnel. It will be observed that no trains are
running in this air tunnel so long as it is so used; there are similar
doors for the working tunnel, but they are kept open, unless either of
them is required to be made into an air tunnel, so that the passing
trains run no risk of running into the doors. By means of the doors
above mentioned, any one of the three tunnels can be used as a fresh-air
tunnel, in which the men doing the repairs to the road would be clear of
the traffic, while the other two are used for the traffic, as well as
outlets for the mixed impure gas and air. If a breakdown of a train
occurs in any one tunnel, that tunnel can at once be converted into a
fresh-air one, while its traffic is transferred to the one previously
used for air, thereby avoiding delay. The system described for splitting
the air and drawing off the noxious gases is very similar to that
described by Mr. Hawkshaw at Southampton. The valves and other details
being added, to make the system applicable to three tunnels, it will
be obvious that other modes of ventilation may be adopted. In order to
reduce the number of men working in the tunnel it is proposed, if found
practicable, not to adopt the ordinary ballast and cross sleepers, but
to substitute the longitudinal timber system, the timbers to be secured
to brickwork or concrete, forming a part of the tunnel lining, placing
efficient elastic material between the foundation and longitudinals for
their whole area, also between the rails and sleepers. An open drain is
formed between the rails; by this plan any water accumulating flows over
smooth surfaces through small channels into a drain, the tunnel on each
side being dry. The saving of labor in repairs, if this system can be
employed, is so evident that a large amount of money might be expended
in endeavoring to discover a suitable elastic material for the purpose.
There are data on many long viaducts sufficient to justify experiments
being made on the subject, and it is not unreasonable to expect that
suitable material may be met with. In very long tunnels nothing should
be omitted tending to reduce the number of men working in them. The
opinion was expressed that in tunnels passing through solid materials,
and proper foundations being made for the longitudinals to rest upon,
with good elastic material placed between the rails and sleepers and
foundations, one-half of the men employed on the ordinary cross sleeper
road resting on ballast would be saved, more particularly as the repairs
are effected in pure air free from the traffic as explained. The
estimate as to the cost of this system was upon the dimensions given by
Sir J. Hawkshaw, and the following gives the comparison:

The quantity of excavation and brickwork or concrete in each case will
be as follows: Single tunnel: 30 ft. diameter lining, 3 ft. thick, with
the brickwork forming the air passage = to 36.5 cubic yards per yard
forward. Excavation to outside of brickwork 36 ft. diameter = to 113
cubic yards per yard forward. Three tunnels 17 ft. diameter and 18 in.
brickwork. Brickwork lining for three tunnels = 24.5 cubic yards per
yard forward. Excavation outside brickwork for the same 105 cubic yards
per yard forward. It is assumed that three 17 ft. tunnels are stronger,
more conveniently formed, and involve less risks in construction than
one of 30 ft. diameter; at the same time there is no difficulty in
making the latter. The above shows the saving in the three tunnels of
23 per cent. in brickwork, and about 7 per cent. of earthwork, compared
with one of 30 ft. With regard to ventilation, it is well known that the
power required to force air along passages is practically as the cube of
the velocity; and as the area of the air passages in the single tunnel
is 106 ft. with speed ten miles per hour, and that of one of the 17 ft.
diameter is 227 ft., or rather more than double, giving only five miles
per hour velocity, it follows that the power for this portion would be
eight times less. That for the working tunnels would be practically the
same, the velocities being nearly alike in both cases, which would be
about 2½ miles per hour--the 30 ft. having an area of 470 ft., the
two single ones together about 450 ft. Upon the face of it the system
deserves a trial. A full consideration of the scheme by engineers
preparing plans for new tunnels would no doubt throw further light
upon the subject and be of interest wherever such work is
contemplated.--_Contract Journal_.

       *       *       *       *       *




MONT ST. MICHEL.


Every one who has the slightest regard for historical monuments, who
values mediæval architecture, or cares in the least degree for the
beautiful and the picturesque, must heartily sympathize with M. Victor
Hugo in his protest against the proposed scheme for uniting the
wonderful island of Mont St. Michel with the mainland by means of a
_causeway_, and possibly a _railway_!

Those who know Mont St. Michel well, and, like the writer, have spent
several days upon the island, cannot but feel that such a scheme would
not only be a frightful disfigurement, but would entirely destroy all
the associations and the poetry of the place. Practical people will
say, "Modern improvement cannot stop in its march forward to consider
poetical associations and mere artistic whims and fancies." Now, this
would be a possible argument if Mont St. Michel were a busy, thriving
town, a commercial port, or the seat of great industries; but in a case
where the only trade is that of touting, the only visitors sightseers,
the only "stock-in-trade" mediæval remains, surely, from a practical
point of view, anything which will injure these antiquities will really
destroy the importance of the island, as its _only_ value consists in
its wonderful historic and artistic associations.

[Illustration: MONT ST. MICHEL, NORMANDY.]

The first glimpse of Mont St. Michel is strange and weird in the
extreme. A vast ghostlike object of a very pale pinkish hue suddenly
rises out of the bay, and one's first impression is that one has been
reading the "Arabian Nights," and that here is one of those fairy
palaces which will fly off, or gradually fade away, or sink bodily
through the water. Its solemn isolation, its unearthly color, and its
flamelike outline fill the mind with astonishment.

Mont St. Michel is by far the most perfect example of a mediæval
fortified abbey in existence, with its surrounding town and
dependencies, all quite perfect; just, in fact, as if time had stood
still with them since the fifteenth century. The great granite rock
rises to the height of two hundred and thirty feet out of the bay; it
is twice an island and twice a peninsula in the course of twenty-four
hours. The only approach is at low water, by driving or walking across
the sands. When, however, one arrives within a few yards of the solitary
gate to the "town," walking or driving has to be abandoned, and here
the commercial industries of the inhabitants commence. A number of
individuals, half sailors and half fishermen, are standing ready to
carry you on their shoulders over the small gully, which is very rarely
quite dry. Entering through the old gate one sees two ancient pieces
of cannon taken from the English, who unsuccessfully laid siege to the
place in 1422. Close to the gate are the two rival inns, which are very
primitive in their arrangement, the entrance hall forming the kitchen,
as in many old Breton houses. A second frowning old gateway leads to the
single street, which, passing between two rows of antique gabled houses,
and under the chancel of the little parish church, conducts one to the
almost interminable flight of stone steps leading to the gateway of
the monastery. Upon ringing the bell a polite lay brother opens the
iron-studded door, and we are admitted into a solemn, vaulted hall, with
another stone staircase opposite. Here we go up and up, to a second
vaulted hall, where, in olden times, we should have had to give up any
arms which we were carrying. Then another stone staircase, which lands
us in a small court with a well in it, at the opposite end of which is a
heavy and solid arched doorway. We pass through this, expecting to find
ourselves on the top of the central tower of the church at least, and
are surprised to find ourselves in the solemn and almost dark crypt of
the church. Here we have climbed up some 230 feet above the world and
the sea to find ourselves in an underground vault; up in the air and
down under the rock at the same time. Wonderfully beautiful is this
strange crypt, when one's eye gets accustomed to the gloom, with its
exquisite ribbed and vaulted roof, supported upon huge circular columns.
Returning to the court, another doorway conducts us into a most superb
Gothic hall, with a row of slender columns down the center. This was the
monks' refectory in ancient times; adjoining this is another grand hall,
divided into four aisles by rows of granite columns, all of the most
perfect thirteenth century work. Above these are two other halls, still
more magnificent than those below. One of these, called the "Salle des
Chevaliers," is probably the most beautiful Gothic hall in existence.
Again a flight of stone stairs, and we find ourselves, where we should
certainly not have expected, in the cloisters of the monastery, the
exquisite architecture of which, with its countless marble columns and
delicate double arcades, cannot be described.

The church deserves a few words, as it is a veritable cathedral as to
size and grandeur. The choir is immensely lofty, and constructed of
granite most elaborately wrought in the later Gothic or flamboyant
style. The nave and transepts are in the old Romanesque style, with
solid pillars and low round arches. The church is beautifully kept, and
contains some very interesting old reredoses and altars with carving in
alabaster. The one modern altar in the Lady Chapel is composed entirely
of silver! Our space will not permit us to describe the numerous
interesting old Abbey buildings--the library, the prior's lodging, the
vast kitchen, the prisons, the dungeons, and the means of supplying the
place in times of siege. The proposed causeway would join the island to
the left of our view, and our readers can imagine the abominable effect
of a high embankment disfiguring this point, and breaking through the
interesting old walls and towers, with, perhaps, a Brummagem Gothic
station against the old time-worn gateway.--_H. W. Brewer, in London
Graphic_.

       *       *       *       *       *




ADORNMENTS OF THE NEW POST OFFICE AT LEIPZIG.


The cuts given herewith, taken from the _Illustrirte Zeitung_, represent
two statues for the new Post Office at Leipzig. The sculptor, Kaffsack,
has represented the post and the telegraph as winged female figures. The
figure representing Mail holds a horn or trumpet in her left hand, and
a letter in her right hand. The figure representing Telegraphy holds a
bunch of thunderbolts in her left hand, and unrolls a band for receiving
dispatches with her right hand. It will be observed that the figure
representing Telegraphy is made much lighter and more graceful than the
figure representing Mail, and has also a more energetic expression of
countenance, thus indicating the greater speed of Telegraphy.

[Illustration: ADORNMENTS OF THE NEW POST OFFICE, LEIPZIG, GERMANY.]

       *       *       *       *       *




COAL GAS AS A LABOR-SAVING AGENT IN MECHANICAL TRADES.

By THOMAS FLETCHER, F.C.S.


Gas, as a fuel, is an absolute necessity to the economical carrying out
of many commercial processes. It is often used in the crudest and most
costly way; a burner may be perfect for one purpose, yet exceedingly
wasteful for another, and however good it may be, an error of judgment
in its application may lead to its total condemnation. An excess of
chimney draught, in cases where a flue is necessary, may pull in
sufficient excess of cold air to almost neutralize the whole power of
the burner, unless a damper is used with judgment. With solid fuel, an
excess of draught causes more fuel to be burnt, but with gas the fuel
is adjusted and limited; there is no margin or store of fuel ready to
combine with the excess of air, which, therefore, lowers the amount
of work done by its cooling power. The power of any burner, for any
specified purpose, depends not only on its perfection, but to a far
greater extent on the difference in the temperature of the flame and of
the object to be heated. For instance, if a bright red heat is required,
it is not possible to obtain this temperature economically with any
burner working without an artificial blast of air; the difference
between the temperature of the flame and that of the object heated is
too little to enable the heat to be taken up freely or quickly, and
the result is a large loss of costly fuel. If we want to obtain high
temperatures economically, an artificial blast of air is necessary,
and the heavier the pressure of air, the greater the economy. On the
contrary, low temperatures and diffused heat are obtained best by flames
without any artificial air supply.

For such purposes as ovens, disinfecting chambers, japanners' stoves,
founders' core drying, and similar requirements the best results are
obtained by a number of separate jets of flame at the lowest part of the
inclosed space, and the use of either illuminating or blue flames is a
matter of no importance, as the total amount of heated air from either
character of flame is the same. If there is any preference, it may be
given to illuminating flames, as the proportion of radiant heat is
greater, and this makes the average temperature of the inclosed space
more equal; but on the other hand, may be considered the greater
liability of the very fine holes, necessary for illuminating flames, to
be choked with dust and dirt. This may, to a great exent, be obviated
by using very small union jets, and setting them horizontally, so as
to make a flat horizontal sheet of flame. Burners placed this way are
practically safe from the interference of falling dust or dirt, but not
from splashes. Falling dirt or splashes must always be considered in the
arrangement of any burners, and the ventilation must be no greater than
is absolutely necessary for the required work. In cooking, this limit
of ventilation may be exceeded, as most things are better cooked with a
free ventilation, the extra cost of fuel being well compensated for by
the better quality of the result.

The air in an oven or inclosed space heated by flames inside is similar
in character to highly superheated steam. It contains a large proportion
of moisture, and yet has the power of drying any substance which is
heated to near its own temperature. A mass of cold metal placed in
the oven is instantly bedewed with moisture, which dries up as the
temperature of the metal rises. This is, for many purposes, an
objection, and the remedy is to close the bottom of the oven and place
burners underneath. If for drying purposes and a current of air is
necessary, the simplest way is to place in the bottom of oven the a
number of tubes hanging downward in such a position that the heat of the
flame acts both on the bottom of the oven and the sides of the tubes,
which, of course, must be long enough for the lower opening to be well
below the level of the flame. The exit may be at any level, but for
drying purposes it is better at the top, and it should be controlled
by a damper to prevent cooling by excessive currents of air. If not
otherwise objectionable, the arrangement of flames inside the oven is
far the most economical in use.

Where an oven or drying chamber is used continuously, it should be
jacketed with slag wool or boiler composition, but for many purposes
this is no advantage. As an example both ways, I will instance the
drying of founders' cores where there is only one blow per day. The
cores of an ordinary foundry can be dried by gas in a common sheet iron
even in about half an hour; any accumulation of heat after that time
would be useless, and a jacketed oven would be of no advantage.

For the disinfection of clothes in vagrant wards and hospitals for
infectious diseases, on the contrary, a continued heat is necessary, and
in this case the accumulation of reserve heat, which takes place slowly
in a jacketed oven, becomes of value, as the gas can be turned low or
out, and the ventilators closed, insuring a more complete disinfection
with a much smaller gas consumption. Where an oven or heated chamber is
much used for periods of over half an hour at once, a non-conducting
casing pays well by reduced gas consumption.

For albumen and glue drying, leather enameling, tobacco drying, and
purposes where a large space has to be very slightly and equally warmed
when the weather is unfavorable, steam-pipes are generally used, but,
not being always available, an exceedingly good arrangement may be made
by placing at intervals in the room gas burners, of any construction,
close to the floor, and surrounded with a sheet-iron cylinder, say 2 ft.
or 3 ft. high. The top of these cylinders must be connected throughout
with a fairly large flue, which will take the products of combustion
from the whole, and this flue must be carried either horizontally, or
with a slight rise, so as to utilize all the waste heat. The reason for
having a number of stoves at intervals is that the heat in a flue will
not carry, for any useful purpose, more than about 8 ft. or 10 ft., and
a single stove would give an irregular temperature in any except a very
small room. If all are not used at once, the flues of those not in use
may be closed by a damper to prevent down draught. The use of hot water
pipes heated by gas may also be occasionally advisable, but, unless for
some special reason, it is much more economical to use coal or coke, as
the bulk of water makes an exceedingly good regulator, and makes a fire
practically as steady and reliable as gas, thus superseding the more
costly fuel.

For one of my own purposes I need hot-water pipes, having very little
variation in temperature night and day; and using coke for economy's
sake, I get a regular temperature by heating a large quantity of water,
about 200 gallons, with the fire, and inclosing this in a tank jacketed
with slag wool. My circulating pipes run from this tank, and a
practically steady temperature, night and day, can be obtained with the
most irregular firing, and occasional extinction of the fire for several
hours at once.

For the heating of liquids, the greatest economy is to be obtained
from one single flame, of as high a temperature as can conveniently be
obtained, and the flame must be in actual contact with the vessel to be
heated. In jacketing vessels, to prevent draughts, care must be taken
that the jackets do not cause currents of cold air to rise rapidly up
the sides of the vessel, and so cool it. If this is the case, the use of
a jacket, instead of being an economy, is a positive expense, and waste
of heat. Many processes, such as making oil and turpentine varnishes,
require a heat under instant control, and in these the use of gas is an
important matter, as the loss and risk of fire are very serious elements
of expense, more especially in small works where special and costly
preparations for contingencies cannot be afforded. I have here a burner
which, for its power, is, perhaps, the most compact and gives the
highest temperature of any burner yet known, and it is easily made in
almost any size; it has, I think, many special advantages. The use of
gauze, which is its only weak point, is more than compensated for by the
very high duties obtained in practice with it, owing to the compactness
and concentration of the heat obtained. The following extract from my
communication to the Gas Institute will give all particulars as to the
constructive detail of this burner. Those who wish to go further into
the matter will find the paper referred to in the publication of the
Gas Institute for the current year, and also in the _Journal of Gas
Lighting_, June 26, 1883, and the _Review of Gas and Water Engineering_,
June 16, 1883.

"The first and most important part is the mixing chamber or tube, one
end of which is supplied separately with gas and air, which at the other
end are, or should be, delivered as a perfect mixture. It may be taken
as a rule that this tube, if horizontal, should not be less in length
than four and a half times or more than six times its diameter. It is
a common practice to diminish or make conical-shaped tubes. All my
experience goes to prove that, excepting a very trifling allowance for
friction, the area of the smallest part of the tube rules the power, the
value of the mixing-tube being no more than that of the smallest part.
If the mixing-tube is upright, new sources of interference comes in;
notably the varying specific gravity of the mixture. Except with one
definite gas supply, the result is always more or less imperfect, and
regular proportions cannot be obtained. This is now so well known that
the upright form has been practically discarded for many years, and
is now only used where the peculiar necessities of the case give some
special advantage.

[Illustration: Fig. 1. SPECIAL HIGH POWER BURNER. SHEWING ATTACHMENT B
WHEN USED WITH A BLAST OF AIR]

"The diameter of the mixing tube is a matter of importance, as it
rules the quantity of gas which can be satisfactorily burnt in any
arrangement. With large flames, given a certain size of gas-jet, the
diameter of the mixing-tube should be not less than ten times as great.
For instance, at 1 inch pressure, a jet having a bore of 1/8 inch will
pass about 20 cubic feet of gas per hour. To burn this quantity of gas,
a mixing tube is necessary 10/8 or 1¼ inch in diameter. By the first
rule this tube must be in length equal to four and a half times its
diameter, or 5-5/8 inches. It would appear that the mixing-tube, having
100 times the area of the gas jet, is out of all proportion to the size
necessary for obtaining a mixture of one of gas to nine or ten of air;
but it must be remembered that the gas is supplied under pressure. It is
therefore evident that no mere calculation of areas can be taken,
into account, unless the difference in pressure of the supply is also
considered. A complete reversal of this law is shown in that ruling the
construction of blowpipes, which I have already given in a previous
paper on 'The Use and Construction of the Blowpipe.' In these the air
supply, being under a heavier pressure, is much smaller in area than
the gas inlet; and, to obtain maximum power, the air-jet requires to be
enlarged in proportion to the gas pressure.

"Given a certain area of tube delivering a combustible mixture, the
outlet for this mixture must be neither more nor less than the size of
the tube. Taking an ordinary drilled tube, such as is commonly made, and
of the dimensions before given--i. e., 1¼ inch bore--if the holes are
drilled 1/8 inch in diameter the tube will supply 10 x 10 = 100 of these
holes. In practice this rule may be modified.

"The variations from the rule, however, must be a matter of experience
with each form of burner. There is also the fact that with small divided
flames it is not necessary to mix so large a proportion of air, as each
flame will take up air, on its external surface; but in this case the
flames are longer, hollow, and of lower temperature. As a matter of
actual practice, where a burner is used which gives a number of flames
or jets, the diameter of the mixing-tube does not need to exceed eight
times the diameter of the gas jet; the remainder of the air required
being taken up by the surfaces of the flames.

"Wire gauze, made of wire the thickness of 22 iron wire gauge, 20 wires
to the linear inch, and tinned after weaving, has an area in the holes
of ¼ its surface. By calculation, the area of a gauze surface in a
burner should, therefore, be taken at four times that of the tube, and
our standard of 1¼ inch tube requires a gauze surface of 2½ inches in
diameter. This rule is subject to variation in burners of a small size,
owing to the air that can, if required, be taken up by the external
surface of the flame, which, of course, is much greater in proportion in
a small flame than in a large one. Where the diameter of the gauze is,
say, not over one or two inches, the theoretical maximum gas supply may
be exceeded, and a varying compensation is necessary with each size.
My rule is intended to apply to burners of larger diameters, where the
external air supply plays a comparatively unimportant part.

[Illustration: Fig. 2.]

"It must be remembered that burners of this class, which burn without
the necessity of an external air supply in a flame which is solid,
require the mixture to be correct in proportions. A very slight
variation makes an imperfect flame. Not only does the gas jet require
to be adjusted with great precision, but it also needs more or less
adjustment for different qualities of gas. An ordinary hollow or divided
flame is able to take up on its surface any deficiency of air supply;
but with the high power solid flames the outside surface is small, and
the consequence is that one of these burners, adjusted for gas of poor
quality, may, when used with rich gas, give a long hollow or smoky
flame, unless the gas jet be reduced in size. When perfect, the flame
shows a film of green on the surface of the gauze; and if a richer gas
is used, the green film lifts away. To cause this to fall again, and to
produce a solid flame, it is necessary to take out the gas jet, and
tap the end with a hammer until, on trial, it is found correct. If too
small, the green film lies so closely as to make the gauze red hot.
Where the 'tailing up' of the carbonic oxide flame is objectionable,
there is no practical difficulty whatever in constructing these burners
as a ring, with an air supply in the center, which greatly reduces the
length of the 'tail.' In practice it is a decided advantage to have a
center air-way in all burners of more than about 2 in. diameter, as it
enables the injecting tube to be slightly shortened, and lessens the
liability of the green film to lift with varying qualities of gas. In
this class of burner I have adopted the small central air-way as a
decided improvement in the burners."

In such processes as the roasting of coffee, chiccory, grain, etc., a
diffused heat is necessary, but of much greater intensity than can be
obtained with economy from heated air. In these cases the application of
a direct flame is necessary, and it may be in actual contact with the
substances to be heated, provided these are kept in constant and rapid
motion.

The use of a revolving cylinder brings in complications with any burner
which is supplied with gas at ordinary pressures without any artificial
air supply, as the currents of air caused by the motion of the cylinder
interfere with the satisfactory working of any burner; and the air
supply must be either protected from draughts and irregular air
currents, or the air must be applied artificially from some independent
source. One exceedingly good way of making any burner work,
independently of the currents caused by a revolving cylinder, is to
apply the flame inside the cylinder at the center, making the substances
to be heated to fall in a continuous stream through the flame. This
system is not applicable to fine powders or sticky substances, as it
necessitates the perforation of the cylinder, to allow of the escape of
products of combustion.

For this class of work, a very concentrated heat is not desirable, as a
rule, and a slit or a perforated burner is preferable. Of this class of
burner I have here a sample, which is not only new in its constructive
details, but has great and special advantages for many purposes. As
you see, it resembles a number of ordinary furnace bars, with this
difference, that each bar is a burner; in fact, it is an ordinary
furnace grate, which supplies its own fuel. With the usual day pressure
of gas=1 inch of water, this burner will, at its maximum power, consume
about 100 cubic feet of gas per hour per square foot of burner surface,
and as it can readily be made almost any form or size, its adaptability
for a great number of uses is evident. I have made it in many sizes and
shapes, to give flames from ½ inch wide by 5 feet long to large square
or oblong blocks. By applying a blast of air at the ordinary gas jets,
and supplying the gas by a separate pipe, or series of pipes, below
the open end of the burner, this can be converted into a furnace of
extraordinary power. It is quite possible to burn as much as 2,000 cubic
feet of gas per hour per square foot of burner surface, producing a heat
sufficient to fuse any ordinary crucible. You see its power when I place
a bundle of iron wire in the flame; it is, in fact, a concentration of
hundreds or thousands of powerful blowpipe flames in one mass. It has
also this advantage, that with a blast of air it will burn and work
equally well any side up, and the flames can therefore be directed
straight on their work without loss. It is, in one form or another,
almost a universal burner, as it can be readily adapted to almost any
purpose, from tempering a row of needles to making steam for a 200 horse
power steam engine. It is easy to make, easy to manage, practically
indestructible, and for commercial purposes has, I think, a general
adaptability which will bring it, in one form or another, into almost
universal use. I may say that when we are in a special fix, this has in
every case landed us out of the difficulty.

For heating large plates of metal equally, for drying paper impressions
for stereotypers, hot pressing hosiery, crumpet baking, working up
plastic masses which can only be worked hot, and work of this class, a
number of separate flames equally diffused under the whole surface of
the plate are necessary to equalize the heat, unless the plate is very
thick, and these are better if produced by a mixture of gas and air; but
in heating wide plates one difficulty must always be remembered, the
burnt gases from the center flames can only escape by passing over the
outer flames, and therefore a space must be left between the top of the
flame and the plate, or the outer flames will be smothered and make a
most offensive smell.

In hosiery presses, printers' arming presses, and many others, the top
plate also requires to be heated. The best way to do this is to use a
number of blowpipe flames directed downward. In many cases the supply
of air under pressure is a practical difficulty and objection. This is
overcome, to a certain extent, by the use of a thick upper plate with a
number of horizontal holes, into which a Bunsen flame is directed. In
every case I have seen, without one single exception, the holes are
either too small, or the burner is placed too close, and the consequence
is that the gas, instead of burning inside the holes, as it should,
passes through partially unburnt, and is consumed at the opposite end,
where it is absolutely useless, the flame not being in contact with or
under the surface to be heated, and therefore doing no work. In hosiery
presses this is a great objection, as the holes are so long that an
equal heat is simply impossible, and the only remedy is to use a
blowpipe flame, which forces sufficient air in with the gas to insure
combustion where the heat is necessary. The same remark applies to crape
and embossing rollers.

For the production of heat in confined spaces and difficult position,
the use of an artificial blast of air is becoming an acknowledged
necessity, and the small Roots blowers now made for such purposes, and
driven by power, are coming rapidly into use.

Sometimes a plate is required to be heated to a high temperature in one
confined spot, and, as an example of this, I may take the bluing of the
hands of watches. For this purpose I have made several arrangements,
and perhaps the best is a thin copper plate, bent down at one side to a
right angle. In this angle, underneath, is directed a very fine blowpipe
flame on one spot, and the hands are passed singly over this spot until
the color comes, when they are instantly pushed over the edge. I have
here the arrangement which is generally used for this purpose. For the
bluing of clock hands, a larger and more equally heated surface is
required, and this can be obtained by a small powerful burner without
a blast of air, using a rather thicker plate to equalize the heat. The
same arrangement may be used with advantage for tempering small cutters
for ornamental turning, penknife-blades, etc., and in these cases the
cooler part of the plate is of great value, as it enables the thicker
parts to be slowly and equally heated up; the application of a
mechanical arrangement to pass the articles to be heated in a regular
succession is a matter easily managed.

[Illustration: FIG. 3. BLUEING WATCH HANDS & TEMPERING SMALL TOOLS]

Among other things which have several times come under my notice may be
mentioned cremation furnaces, but I have not yet met, with, or been
able to devise, any burner for ordinary coal gas which has worked
satisfactorily. This fuel is apparently unfitted for the work, and
the best arrangement I know is a number of pipes delivering ordinary
"producer" gas from the Wilson or Dowson generators, in exactly the
same way as is at present used for firing horizontal steam boilers. For
heating book finishers' tools, a ring-flame is the simplest, the tools
being supported a little distance above the flame; the usual plan of
heating a plate, and placing the ends of the tools on this, necessitates
at least double the gas consumption as compared with an open flame.
For type-founding machines, bullet moulding, stereotype metal melting,
solder making, lead melting, etc., one burner, or rather one flame,
should be used of a suitable power for the work, and this should be as
perfect and of as high a temperature as possible to insure economy. It
is now a simple matter, owing to recent researches in the theory of
heating burners, to obtain flames of any power without practical limit,
which, without any artificial air supply, will do all which is necessary
in this class of work, and the required arrangements are exceedingly
simple. With these trades may be classed, also, the concentration and
distillation of acids and liquids boiling at a high temperature, and we
may also include baths for tinning small articles, and the tinning by
fusion of sheet copper, the same burners being applicable, and perfectly
suited to all these requirements, unless the tinning baths are long and
narrow, in which case the furnace-bar burners again come to the front as
the best; as, if we are to use gas economically, the flame must be the
same shape as the vessel to be treated.

We may now consider the heating of blanks for stamping, hardening the
points of spindles, finishing the ends of umbrella tips, and work where
a small article, or a small part of any article, has to be heated to a
high temperature with speed and certainty. For these a long and narrow
flame is necessary, and I may mention that in cases where a high speed
of delivery is required, and a small part only has to be heated, such
as, for instance, in the hardening of the points of spindles for cotton
machinery, I have made burners giving a flame of exceedingly high
temperature only ¼ inch wide and five feet long. This flame is produced
by the assistance of a blast of air, and is of sufficiently high
temperature to fuse the spindle in a few minutes.

The points only project over the flame, and the spindles are carried
mechanically at such a speed that at the end of the five feet traverse
they are red hot, and drop into water. More than one hundred are in the
flame at once, lying side by side.

For heating blanks for stamping, the furnace bar-burner is perfectly
suited, and in this work the chute supplying the blanks to the machine
should be made of two fireclay sides, with an opening for the flame
between the chute and flame being placed at a sharp angle, to prevent
risk of the blanks sticking or overriding each other. A blowpipe may
also be used with good effect, as shown in the above engraving, and in
many cases it is preferable and much easier to manage.

In some cases the direct contact of the flame would spoil the articles
to be heated, and instead of the arrangement mentioned, a tube of iron,
fireclay, or other suitable material is heated, and the articles are
passed through it. This system of continuous feed, through a tube, has
been applied to the firing of small articles of pottery, and might
possibly be well adapted, among other things, to the production of
gas-burners.

[Illustration: FIG. 4.]

Where the contact of air with the heated articles is injurious, many
plans have been tried to keep the ends closed as much as possible, but I
believe no more perfect and simple seal against the admission of air can
be devised than to turn a jet of pure gas, unmixed with air, into each
end of the tube. This is an absolute seal against the entry of oxygen in
an uncombined state; free oxygen cannot exist at a very high temperature
in the presence of coal gas.

For many trades there is a demand for hardened and tempered steel wire,
either round or flattened, and the production of this has led to many
attempts to obtain a satisfactory continuous process. The common method
now, which is worked as a "secret" process by most firms, is to pass
the wire through a tube to heat it, as already described, and to run it
direct from the tube through a hole in the side of a box filled with
oil, the whole being packed with asbestos, to prevent leakage; from this
it is passed through another similar hole on the opposite side, either
over a plate heated to the right temperature, or over a narrow open
flame of sufficient length and power to give the correct heat for
tempering.

Where absolute precision is necessary, the gas supply must be adapted by
an automatic regulator on the main, to prevent the slightest variation
of heat. Once adjusted, the production of flat and round spring wire by
the mile is an exceedingly simple matter. It is quite possible to obtain
absolute precision in temperature by a proper adjustment of the gas
pressure, and as this is, for tempering steel articles and some other
purposes, a matter of great importance, it is worth some consideration.
No pressure regulator alone will give an absolutely steady supply; but
if we put on first a regulator, adjusted to the minimum pressure of
supply, say one inch of water, and then fix another on the same pipe,
adjusted to a slightly lower pressure, say 9/10 of an inch, the first
regulator does the rough adjustment, and the second one will then give
an absolutely steady supply, provided always that the regulators are
both capable of passing more gas than is likely to be ever required. No
regulator can be relied on for absolute precision, if worked up to its
maximum possible capacity.

[Illustration: Fig. 5. ARRANGEMENT FOR HEATING BLANKS FOR STAMPING OR
HARDENING.]

Among other applications of a long narrow flame of high power, may be
mentioned the brazing of long lengths of tube, in fact the application
of flames of this form, with and without a blast of air, for different
temperatures, are almost endless.

The thousands of uses to which blowpipes are adapted are so well known,
that they need no mention, except the curiously ignored fact that the
power of any blowpipe depends on the air pressure. A compact flame of
high temperature cannot be obtained except with a heavy air pressure,
and the ignorance of this fact has caused an immense number of
unexplained failures. Many people think that one blower is as good as
another, and expect that a fan giving a pressure equal to, say, the
height of a two inch column of water should do the same work as a blower
giving a pressure ten to twenty times as great. The construction and
power of blowpipes, with the laws ruling the proportions and power, will
be found in an article on "Blowpipe Construction," published in _Design
and Work_, March, 1881, and as the matter is there fully treated, no
further reference to the subject is necessary.

In the more recent forms of gas-engine, the charge is exploded by a
wrought iron tube, heated to redness by the external application of a
gas flame. This, although considered satisfactory by the makers, appears
to me to be an exceedingly crude way of getting over the difficulty; and
I offer it as a suggestion, that a very small platinum tube shall be
used instead of iron. This, if made with a porous or spongy internal
coating, would fire the charge with certainty, at a lower temperature
than iron, and it could be made so thin and small in diameter, without
risk of deterioration or loss of strength, that an exceedingly small
flame could be used to heat it up. As it would be fully heated in a very
few seconds, the delay in starting would be obviated.

[Illustration: Fig. 6.]

There are many purposes for which a red heat is needed for slow
continuous processes on a small scale, such as case-hardening small
steel goods, annealing, heating light steel articles for hardening, and
a great variety of other similar processes. This, until recently, has
required the use either of a rather complicated furnace, or a blast of
air under pressure, to increase the rapidity of combustion. Since the
conclusion of my experiments on the theoretical construction of burners,
I have found that the high-power burners, previously described, are
capable of heating a crucible equal in size to their own diameter
to bright redness without the assistance of a chimney, provided the
crucible is protected from draughts by a fireclay cylinder.

This is an important point, as it renders the production of a continuous
bright red heat a matter of the greatest ease, even in crucibles of a
comparatively large size. Where the heat is steady, and certain not to
rise above a definite point, it can safely be used for such purposes as
hardening penknife blades and other articles which are very irregular
in thickness, the thin edges not being liable to be burnt or damaged by
overheating.

For the highest temperatures air under pressure is a necessity, as we
require a large quantity of gas burnt in as small a space as possible
with the maximum speed, and given this air supply, we are very little
hampered by conditions, as an explosive mixture may be blown through a
gauze into a fireclay chamber, closed, except so far as is necessary to
allow the escape or burnt gases. The speed of combustion is limited only
by the speed of supply of air and gas, and by increasing these there is
no practical limit to the heat which can be obtained. When we have to
do with the reduction of samples of refractory ores, testing the
comparative fusibility of different samples of firebricks, or alloys,
etc., the use of an explosive mixture blown into and burning in a
close chamber is invaluable, and the ease and certainty with which
any temperature may be obtained has led to great discoveries, and the
revolutionizing of many commercial processes. Recent experiments have
proved that, by a modification in the form of the well-known injector
furnace, an enormous increase of temperature may be obtained. I have,
in actual work, obtained the fusing point of cast iron in two minutes,
starting all cold, and have fused every furnace casing I have yet been
able to produce. If infusible casings can be made, I think I am not
overstating facts in saying that any temperature required can and will
eventually be obtained with the greatest ease. What the limit is I have
as yet not been able to discover.

There is one more application of gas, as a fuel, which, discovered and
published by myself some two years ago, has yet to become generally
known, and in some special processes may prove exceedingly valuable.
This is the addition of a very small quantity or coal gas, or light
petroleum vapors, to the air supplied by a blower or chimney pull,
to furnaces burning coke or charcoal. The instant and great rise in
temperature of the furnace, and the greater stability of the solid fuel
used, are extraordinary. This is, in fact, a practical application of
the well-known "flameless combustion," the only signs that the gas
is being burnt being a great rise in temperature and a decreased
consumption of the solid fuel; in fact, if the gas is in correct
proportion, the solid fuel remains unburnt, or nearly so, in spite of
the high temperature. In cases where a sudden rise in temperature is
required in a furnace, or where the power is deficient, this method
of supplementing and increasing the heat will be found of very great
service, and processes liable to be checked by making up a fire with
fresh fuel can be carried on without check, even after the solid fuel
has almost entirely disappeared.

That a solid fuel is quite unnecessary, I will prove in a very simple
manner, by burning a mixture of coal gas and air without a flame, in a
bundle of iron wire. The heat is sufficient to fuse the wrought iron
with ease, and the glare inside the bundle of wire is painful to the
eyes. The same result could be obtained by a pile of red-hot lumps of
firebrick, and the same heat obtained also without a trace of flame.

It is not possible to enter fully into such a wide and important subject
in a single lecture, and the suggestions now given are simply hints for
the guidance for those who need or desire to experiment. No doubt we
shall have, after a time, some text-books and other literature on this
subject, which is one of great importance to many industries; and it is
necessary for experimental work and applications to new industries, that
the experimenter shall not only be able to purchase special burners, but
that he shall have fundamental laws laid down which will enable him to
construct them for himself, so as to have his experiments under his own
control. The difficulty in the way of literature on the subject is that
those few who have worked in the matter are busy men, with little time
which is not already fully employed.

Pioneers on new ground have a great liability to generalize and jump at
conclusions, and the necessary exact work and detail must, to a great
extent, be left to those who follow on tracks already roughly marked
out.

Of the special trades which have come under my observation, I have only
had time to mention a very few. It appears to me that there are very few
manufacturing processes of any kind which could not be simplified by the
use of gas as a fuel, from the production of electric light apparatus
to the manufacture of explosives, cotton stockings, beer, catgut, glue,
umbrellas, ink, fish-hook, medals, stained glass windows, brushes, and
other trades equally various, which come daily under my own notice.

       *       *       *       *       *

A man was received into the Laborisière Hospital, Paris, the other day,
with a yard of rope hanging from his mouth. Traction upon the cord
revealed a section of clothes line measuring eight feet. He had been
surprised in an attempt at suicide and had tried to conceal his design
by swallowing the cord. He lived, of course--they generally do.

       *       *       *       *       *




INSTANTANEOUS PHOTOGRAPHY.


A certain number of the readers of this journal are occupied with
photography, and all assuredly are interested in this marvelous art,
whose progress is so remarkable. So it has seemed to us that it would
be of interest to treat of a question that is the order of the day. We
desire to speak of those photographic apparatus called instantaneous
shutters.

Numerous apparatus of this kind have been proposed to the public, and
several even have been described in this journal, but we have to state
that, despite the success in certain cases, none of them has proved
remarkable for its qualities and superiority. This is due, we believe,
to the fact that inventors, while showing arrangements that were often
ingenious, have not always taken into account the end that the shutter
is to subserve, and the qualities that it must possess in order to
attain such end.

In face of the progress made by extra rapid dry processes, the question
of shutters has become the most important, since cabinet-making, optics,
and photographic chemistry give us apparatus, objectives, and products
which, although they will doubtless be improved upon, satisfy for the
present all our needs.

What is understood by instantaneousness? To our knowledge, no definition
thereof has as yet been given. For our part, we propose to style
"instantaneous" any photograph that is taken in a fraction of a second
that our senses will not permit us to estimate. The shutter is the
apparatus which allows the light to enter the photographic chamber
during this very short time.

In order to examine the different rules that govern the question of
shutters, we shall take as an example the type styled the "Guillotine."

This apparatus, as every one knows, is a stiff plate containing an
aperture and passing over the line of the rays of light. Some place
it in front and others behind, while others again place it within the
objective. Let us examine and discuss what occurs in the three cases.
Suppose a rectilinear objective of the kind most usually employed in
instantaneous photography, and an object, A B, that we wish to reproduce
(Fig. 1), the objective being provided with any sort of diaphragm. The
point, A, sends a bundle of rays, a"b", to the first lens. Here they are
slightly refracted, and then go on parallel lines to the second lens,
where they are again refracted and form at A' an image of A. It is this
image that we see upon the ground glass, and which makes an impression
upon the sensitive film. The point, B, behaves in the same way and
gives an image at B', but, as will be at once seen, the image will be
reversed. In our figure, A corresponds to the sky and B to the earth.
If, then, the shutter passes in front of the objective, it will first
allow of the passage of the rays which come from the sky, then, on
continuing its travel, it will unveil the landscape, and lastly the
ground. As it is submitted to the law of the fall of bodies and has a
uniformly increasing velocity, it follows that the time of exposure will
uniformly decrease between A' and B', and that the sky will pose longer
than the foreground. Such a result is contrary to all photographic
rules, which require that objects shall pose so much the longer the
less they are lighted. This position of the "guillotine" shutter is
absolutely false, and must be altogether discarded. If the shutter be
placed behind the objective, it will follow, as a consequence of the
same demonstration, that the time of exposure will go diminishing from
B' to A', and that the foreground will be exposed longer than the sky.
The solution is logical, then, and will permit of obtaining excellent
negatives.

[Illustration: FIG. 1]

Let us now examine how the image, A'B', is formed. The point, A, appears
first, and becomes lighter and lighter up to the moment at which all the
rays that emanate from the point, A, are unveiled. The point, B', is not
yet visible. As the shutter continues its travel the point, B', appears
in its turn and becomes illuminated like the point, A'. At this moment
the objective is completely uncovered; the image, A'B', is perfect, and
possesses its maximum intensity. Then the point, A', gradually becomes
obscured and disappears; and the same is the case with all parts of
A'B'. The image is developed progressively from A' to B', and makes its
impression upon the sensitive plate successively--a fact which, as
may be conceived, may have its importance. If, for example, we are
photographing a ship that is being tossed about by the sea (and we
borrow this example from our colleague, Mr. Davanne), the image of the
top of the mast will not be formed at the same instant as that of the
base, and if the motion of the mast has sufficient extent it may take on
a curved form, due to the fact that it has effected a movement between
the moments during which its apex and base were being photographed.

Upon placing the guillotine shutter in the optical center of the
objective, what will occur? The shutter will permit the passage of an
equal fraction of the rays derived from A and B, that is to say, the
image will be complete from the first instant of the exposure. The
points, A' and B', will be illuminated precisely at the same moment. As
the shutter continues its travel, a fresh quantity of rays coming from A
and B will be admitted, and the image will be illuminated more and more
up to the moment at which all the rays can pass. It will then possess
its maximum intensity. Then a portion of the rays from A and B being
intercepted, the image will become darker and darker until complete
extinction. The image here, then, is not produced successively as in the
former case, but is entire from the beginning. In this case the image of
our mast cannot be misshapen, since it has been accurately photographed
at the same moment.

The true place for the guillotine shutter, then, from a theoretical
standpoint, is in the interior of the objective. Are there any other
advantages to be gained by so placing it? Yes; it is easy to understand
that for the same time of exposure, and consequently for the same
result, the aperture may be so much the smaller in proportion as the
optical center is approached.

The luminous rays, in fact, form in the objective a double truncated
cone whose upper base is equal to the diaphragm, and the lower one to
the diameter of the lenses. If the aperture be equal to any diameter
whatever of one of the cones, the result will be the same; but, for
the same period of exposure, it will evidently prove advantageous to
approach the diaphragm. The ratio of the apertures that give the same
results at the optical center or behind the objective is as that of the
diaphragm employed to that of the back lens. If the diaphragm is
one centimeter and the lenses four centimeters, an aperture of one
centimeter in one case and of four in the other will give the same
result.

We shall see further along that it is advantageous to employ apertures
equal to several times the diameter of the diaphragm or lens. Now, from
what we have just said, an aperture, equal for example to four times the
diaphragm, will be only 4 centimeters, while the corresponding aperture
behind the lens must be 16. The dimensions of the first will be
practical, and those of the second will give too cumbersome and too
fragile an apparatus. But why must the aperture be larger than the
diaphragm employed? This is what we are going to demonstrate. Let us
make the aperture equal to the diameter of the objective, and see
what occurs at the different periods of the exposure. For the sake of
clearness, we shall suppose the velocity uniform.

It is evident, _a priori_, that a perfect apparatus will be the one that
will allow the light to act during the entire exposure with a maximum of
intensity. Is it thus, when the aperture is equal to the diameter of the
objective? Evidently not. Let us consult Fig. 2. We here see the shutter
progressively uncovering the objective. The light will increase from A
to C up to the moment when the objective is entirely uncovered, and will
then immediately decrease up to B. The objective has operated with a
maximum of light for only a short time. We are far from the ideal result
in which the maximum of light, CD, should exist during the entire
exposure, and form the upper plane precisely equal to AB.

[Illustration: Fig. 2.]

If we cannot obtain such a result in practice, we must nevertheless
aproximate to it. We shall do so by increasing the shutter. Up to C' the
apparatus will operate as before, but from C' to D' the aperture will be
complete, and from D' to B' will decrease as has been said.

Let us give A'B' the same value as AB, that is to say, let us increase
the velocity in the second case in order that the time of exposure shall
be the same; we shall at once see that in the first case the object will
be completely uncovered for only a very short time, while in the second
the exposure will be perfect for a very appreciable period.

The time of exposure which is absolutely active, we propose to call
effective time of exposure in contradistinction to the total time of the
same. The more we increase the value of C'D', that is to say, that of
the effective time, the more the ratio, C'D'/A'B', will approximate to
unity, and the nearer we shall reach perfection. The correlative of such
elongation of the aperture is an increase in velocity which will always
bring the total exposure to the same figure, whatever be the aperture
employed.

If the aperture be equal to two diameters, the effective time will be
equal to half the time of the total exposure; and if it is equal to
three diameters, the exposure will be good during 2/3 of the total time.
This amounts to saying that the effective time of exposure is equal to n
times the diameter--1, the velocity being supposed always uniform. If
we place the shutter within the objective, it is the diameter of the
diaphragm that it will be necessary to say. The effective time will be
equal then to n diaphragm--1.

From what precedes it results that in no case should the aperture be
inferior to the diaphragm, since the former would otherwise absolutely
suppress the effective time in giving a lower plane corresponding to
an insufficient quantity of light. Moreover, an aperature of this kind
would prove injurious to the quality of the image by successively
uncovering rays which do not form their image identically at the same
point. We are now, then, in presence of results that are absolutely
positive, and they are as follows:

1. The guillotine shutter should be placed in the interior of the
objective and as near as possible to optical center, that is to say,
behind the diaphragm, since the latter is precisely in the optical
center.

2. The aperture should be as wide as possible.

3. The velocity should be as great as possible.

In practice, an aperture from 4 to 5 times the diameter of diaphragm
employed will be more than sufficient, since we shall have, according to
circumstances, ¾ or 4/5 of the effective time. Moreover, whatever be the
time of exposure, this ratio once established will be invariable, and
the apparatus will always operate identically.

A shutter combining these qualities will not yet be perfect. It is
necessary, according to the time and the light, that the time of
exposure shall be capable of being varied. In a word, it is necessary
that the apparatus shall be _graduated_ and permit of taking views more
or less quickly. The different velocities might be given to the
shutter by means of weights, rubber, or springs. The latter seem to be
preferable, since they permit in the first place of operating out of
the vertical; moreover, they are less fragile, and, through different
tensions, they permit of these graduations that we consider as
indispensable. For the current needs of practice 1/100 of a second is a
limit that seems to us sufficient as a maximum of rapidity. In order to
know the time of exposure obtained we employ the following method, which
permits of graduating an apparatus rapidly and with extreme precision:

A band of smoked paper is fixed upon the shutter, then a tuning-fork
provided with a small stylet resting against the paper is made to
vibrate. Better yet, a chronograph which vibrates synchronously with a
tuning-fork, whose motion is kept up by electricity, is put in the same
place. Fig. 3 shows the arrangement to be employed. We then let the
shutter fall, when the little stylet will inscribe a certain number of
vibrations. Knowing the number of vibrations of the tuning-fork, and
counting the number of those inscribed upon the paper, it is very simple
to deduce therefrom the amount of the time of exposure. The results of
one of these experiments we have reproduced in Fig. 4. The tuning-fork
gave 100 double vibrations per second. Six vibrations are included
between the opening and closing of the apparatus. Each vibration
estimated at 1/100 of a second. The exposure was 6/100 of a second in
round numbers. This is the amount of the total time of exposure. As
for that of the effective time, that is just as easily ascertained. It
suffices to know the number of vibrations comprised between the moment
at which one point of the objective has been completely uncovered and
that at which it has begun to be covered again. The time is equal to
2/100 in round numbers.

In the experiment in question, with an aperture equal to twice the
diameter of the diaphragm, we have, then, 1/3 of the half-open exposure;
and the amount of the effective time is 1/3. The difference that we
have in practice is due to the fact that the velocity is uniformly
accelerated. In order to increase the amount of the effective time, it
will be only necessary to increase the aperture of the shutter and apply
again the method that we have just pointed out.

[Illustration: FIG. 3.]

So much for the material part of the apparatus. It will be necessary
in addition to acquire sufficient individual experience to be able to
estimate the intensity of the light, and consequently to judge of the
diaphragm to be employed and the velocity to be obtained. It must not
be forgotten that such or such an object having a relatively slow speed
will not be sufficiently sharp on the negative if it is too near
the apparatus, while such or such another, much more rapid, might
nevertheless be caught if sufficient distance intervened. Here it is
that will appear the skill of the amateur, who will find it possible to
obtain the said object as large as possible and with a maximum degree of
sharpness.

We have seen what diverse qualities should be possessed by a good
guillotine shutter, and it is evident that the same should be found
in all apparatus of the kind. In our opinion the guillotine is a well
defined type that possesses one capital advantage, and that is that it
permits of the use of aperatures as wide as may be desired for the
same time of exposure. It is a question, as we have seen, of velocity.
Consequently, however short the exposure be, it will always be possible
to operate with a full amount of light during the greater part of the
exposure. It is necessary to dwell upon this point, since in another
kind of apparatus that possesses a closing and opening shutter the same
result cannot be reached. In the Boca apparatus, for instance, we remark
that at a given moment the time of exposure is reduced to nothing, as
the closing shutter covers the objective before the latter has been
unmasked by the opening one. In all exposures, in fact, the times of
opening and closing have a constant value. It follows that the shorter
the exposure is, the greater becomes such value, and to such a point
that, at a given moment, the apparatus no longer make an exposure.

[Illustration: FIG. 4.]

In the guillotine, on the contrary, the same space always intervenes
between the time of opening and closing, since it is fixed in an
unvarying manner by the diameter at the aperature. Then, the greater the
velocity, the more the time of opening and closing diminishes. If
the ratio of the effective to the total time of exposure is 3/4, for
example, it will be invariable, whatever be the velocity.

In concluding, we will remark that, without employing springs, we
may increase the aperture of the shutter without varying the time of
exposure. To effect this it is only necessary to raise the point of the
shutter's drop. In fact, as may be seen in Fig. 4, all the vibrations
of the stylet corresponding to 1/100 of a second always continue to
elongate, and it will consequently be possible for the same time of
exposure to considerably increase the aperture and, as a consequence,
the effective time, by causing the guillotine to drop from a greater
elevation. From this study, which has principally concerned the
guillotine shutter, can we draw the deduction that this type of
apparatus will become a definite one? We think not. In fact, along with
its decided advantages the guillotine has a few defects that cannot be
passed over in silence. The aperture, in measure as it is increased,
renders the apparatus delicate and subject to become bent. If, in order
to obviate this trouble, we employ plates of steels, we increase its
weight considerably, and the chamber becomes subject to vibration at the
moment the shutter drops. If rubber or springs are used for increasing
the velocity, it is still worse. Moreover, it is quite difficult to
obtain a graduation, and to our knowledge, and probably for this reason,
it has not yet been applied.

The reader will please excuse us for this perhaps somewhat dry
theoretical _expose_, but we have thought it well to give it in the
hope that it might well show the qualities that should be required of a
photographic shutter and particularly of the guillotine. Moreover, at
the point to which photography has arrived it is no longer permitted to
do things by halves.

After the memorable discoveries of Nicephore, Niepce, Daguerre, and
Talbot, photography remained for some time stationary, limited to the
production of portraits and landscapes. But for a few years past it has
taken a new impetus, and new processes have come to the surface. In the
graphic arts and in the sciences it has taken considerable place. Being
the daughter of chemistry and physics, it is not astonishing that we
require of it the precision of both. It is, moreover, through a profound
study of the reactions that gave it birth and through a knowledge of the
laws of optics that it has come into current use in laboratories. In
fact, it alone is capable of giving with an undoubted character of
truthfulness a durable vestige of certain fleeting phenomena.--

_A. Londe, in La Nature_.

       *       *       *       *       *




FALCONETTI'S CONTINUOUSLY PRIMED SIPHON.


To carry a watercourse over a canal, river, road, or railway, several
methods may be employed, as, for example, by aqueducts like those of
Arcueil and Buc near Versailles, and by upright and inverted siphons.
Of these three means, the first is the most imposing, but is also very
costly; and, besides, the declivities as well as the arrangement of the
ground are not always adapted thereto. The inverted siphon is subject
to obstruction and choking up in its most inaccessible parts, while
the upright siphon is easy of inspection, taking apart, etc. But, _per
contra_, the latter loses its priming very easily by reason of the
formation of air spaces.

[Illustration: FALCONETTI'S SIPHON.]

Mr. Falconetti, an inspector of bridges and roadways, has found a means
of rendering the latter occurrence impossible by an arrangement which
is both simple and practical, and which is illustrated herewith. In the
figure, a and b are the two vertical legs of the siphon, both of which
enter the liquid. These open into the receptacles, c and d, in which the
cocks, e and f, cut off or set up a communication with the pipes, a
and b. These latter are connected by a branch, g, which may be put in
communication with a reservoir, h, that is divided into two superposed
compartments by a partition, i. Such communication may be established
or cut off by a valve, j, maneuvered by a key, k, which traverses
an aperture in the partition, i. Another aperture, m, in this same
partition serves to put the two parts of the reservoir, h, in
communication, and, for this purpose, is provided with a cock, n, which
is easily maneuvered from the exterior.

The object of this arrangement of cocks and reservoir is to prevent the
siphon from losing its priming through the possible presence in the
transverse portion of a certain quantity of air or gas that might be
given off by the water and accumulate in this place.

The compartment, A, of the reservoir, h, is designed for receiving the
gases that collect in the top of the siphon, while the upper compartment
contains water for making a hydraulic joint, and consequently preventing
any re-entrance of air through the apertures in the partition, i.

To prime the siphon, we shut the cocks, e and f, open the valves, j and
m, and pour in water until the whole affair (siphon and reservoir) is
full; then we close the cock, m, and open the three others. The siphon
thus becomes primed, and begins to operate as soon as any water reaches
one or the other of the lower receptacles. As the cock, j, is constantly
turned on during the operation of the siphon, the air that has been able
to accumulate in the lower compartment, A, of the reservoir, h, would
finally unprime the siphon by intercepting communication between its two
legs. In order to prevent such a thing from occurring, it suffices to
expel the air, from time to time, that accumulates in the chamber,
A, this being done, without stopping the operation of the siphon, as
follows:

After closing the cock, j, water is poured into the reservoir, and,
running down to the lower compartment, drives out the air through the
cock, m. This operation once effected, it only remains to turn off the
cock, m, again, and open j in order to establish the normal operation.
As the chamber, A, is provided externally with a water gauge, N, it may
be seen at a glance when it is necessary to maneuver the cocks in order
to expel the air.

This system of siphon is evidently applicable to all sorts of liquids.
It may likewise undergo a few modifications in its construction; for
example, the valve, which in our engraving is placed over the siphon,
may be located at any distance from the apparatus, although it should,
in all cases, be in constant communication with it by means of a tube,
and be placed a little higher than the siphon. It may then be put under
cover and be kept constantly in sight, thus greatly facilitating its
surveillance.

As may be seen, the essential peculiarity of this improvement consists
in the very ingenious arrangement that permits of immersing the cocks in
the liquid to make them perfectly tight, it being necessary that they
should be hermetically closed in order to prevent the entrance of air
to the siphon. Everything leads to the belief, then, that if upright
siphons have never been able to operate regularly, it has been because
no means have been known of expelling the air from the interior without
letting air from the exterior enter at the same time. The arrangement
devised by Mr. Falconetti gets over the difficulty in a very elegant
manner. It seems as if it would be called upon to render great services
in the industries, and it well merits the attention of engineers
of roads and bridges, and of contractors on public works.--_Revue
Industrielle_.

       *       *       *       *       *




THE WEIBEL-PICCARD SYSTEM OF EVAPORATING LIQUIDS.


In the industries, there are often considerable quantities of liquid to
be evaporated in order to concentrate it. Such evaporation is very often
performed by burning fuel in sufficient quantity to furnish the liquid
the heat necessary to convert it into steam. This process is attended
with a consumption of fuel such as to form a very important factor in
the cost of the product to be obtained. In order to vaporize, at the
pressure of the atmosphere, 1 kilogramme of water at 0°, 637 heat units
are required, and of these, 100 are employed in raising the water from
0° to 100° and 537 in converting the water at 100° into steam at 100°.
This second quantity is called the _latent heat_ of the steam at 100°.
The sum of the two quantities is called the _total heat_ of the steam at
100°. The total heat of the steam remains nearly constant, whatever be
the temperature at which the vaporization occurred.

[Illustration: THE WEIBEL-PICCARD EVAPORATION APPARATUS.]

In order to utilize the steam as a means of heating, it is necessary to
condense it, that is to say, to cause it to pass from the gaseous to a
liquid state. This conversion disengages as much heat as the passage
from the liquid to the gaseous state had absorbed.

It results from this that if we could condense the steam that is given
off by a liquid that we are vaporizing, in contact with another liquid
that it is also a question of vaporizing, we should utilize all the heat
contained in the steam that was being given off from the first.

This object can be practically attained by two means, viz., by (1)
putting the disengaged steam in contact with the sides of a vessel that
contains a liquid colder than the one that produced it; (2) by raising
the temperature and pressure of the disengaged steam in order to
condense it in contact with the sides of the vessel which contains the
very liquid that has produced it.

The first of these means is realized in the apparatus called multiple
acting, that are at present so generally employed in sugar works. The
second means, which permits of a greater saving in fuel being made than
the other does, is realized by compressing the disengaged steam. This
compression, which raises the temperature and pressure of the steam,
permits of condensing the latter in contact with the vessel wherein it
has been produced. By such condensation we continuously restore to the
liquid which is being vaporized the heat of the steam which it gives
off.

This solution of the question, which has been partially seen at
different epochs, has but recently made its way into the industries. It
is being operated at present with complete success at the salt works of
France and Switzerland, at those of Austria and Prussia, in the sugar
of milk factories of France and Switzerland, and, finally, in 1882, the
first application of it in the sugar industry was made at Pohrlitz, in
Moravia.

The saving of fuel that has been made in these different applications
has always been great.

We shall now, for the sake of explaining the system, give a brief
description of the apparatus as used at the Pohrlitz sugar works
mentioned above. These works treat 255 tons of beets per 24 hours, and
obtain 4,000 hectoliters of juice, which is reduced to about 1,000
hectoliters of sirup. Up to the present, the concentration has been
effected in a double acting apparatus partly supplied by exhaust steam
from the motive engines and partly by steam coming directly from the
generators.

In order to diminish the consumption of direct steam, these sugar works
put in a Weibel-Piccard apparatus designed to concentrate only a third
of their juice, or about 1,350 hectoliters per day.

This apparatus (see engraving) consists of a steam compressor, 0.835 m.
in diameter, actuated directly by a driving cylinder of 0.5 m. diameter
and 0.8 m. stroke, and of three evaporating boilers of the ordinary
vertical tube type, the first of which has a surface of 150 square
meters, the second 60, and the third 80.

The steam, at the ordinary pressure of the generators, say 5
atmospheres, is taken from the connected generators of the works, and is
led to the driving cylinder, where it expands and furnishes the power
necessary to run the compressor. It then escapes at a pressure of l.4
atmospheres and enters the intertubular space of the first evaporator.
The compressor sucks up the steam from the juice of the first evaporator
(which is boiling at the pressure of the atmosphere, without vacuum or
effective pressure), compresses it to 1.4 atmospheres, and forces it
likewise into the intertubular space. The ebullition of the first
evaporator, then, is kept up not only by the exhaust from the motive
cylinder, but also by the steam from the juice itself, which has been
rendered fit to serve as a heating steam by the pressure that it has
undergone in the compressing cylinder.

In this first application of the new system to sugar making, it became
a question of ascertaining whether the advantage resulting from
compression was of great importance, and, in the second place, whether
the apparatus could be run with certainty and ease. In truth, the
applications of the system for some years past in other industries
permitted a favorable result to be hoped for, and the result turned out
as was expected.

With this apparatus it has been found that the work furnished by one
kilogramme of steam passing through the motive cylinder, from a
pressure of 5 atmospheres to one of 1.4, is sufficient to compress 2.5
kilogrammes of steam taken from the juice, led into the compressor
at one atmosphere and escaping therefrom at 1.4. In other words, one
kilogramme of motive steam is sufficient to convert into heating steam
for the first evaporator 2.5 kilogrammes of steam taken from the juice
in this same evaporator. Besides, this same kilogramme of motive steam
produces three effects, one in this same evaporator, and the other
two in the two succeeding ones. The effect obtained, then, from one
kilogramme of motive steam is, in round numbers, 5.5 kilogrammes of
steam removed from the juice.

It must not be forgotten that the motive steam was at the very moderate
pressure of 4 effective atmospheres. Had the use of steam at high
pressure (7 atmospheres for example) been possible, it is easy to
conclude from the above results that more than 6 kilogrammes of water
would have been vaporized with one kilogramme of steam.

The results here cited were ascertained by accurately measuring the
quantities of water of condensation from each evaporator, they soon
received, moreover, the most important of confirmations by the decrease
in the general consumption of fuel by the generators which occurred
after the new apparatus was set in operation.

The mean consumption of coal per 24 hours for the twenty days preceding
the 18th of November was 86,060 kilogrammes. After this date the regular
consumption was as follows:

  Nov. 19.................31,800 kilogrammes.
   "   20.................33,800     "
   "   21.................33,800     "
   "   22.................32,000     "
   "   23.................31,400     "
   "   24.................31,600     "
   "   25.................30,500     "
   "   26.................30,500     "
   "   27.................28,600     "
   "   28.................30,300     "

It must be remarked that in the perfectly regular running of the sugar
works, nothing was changed saving the setting of this evaporating
apparatus running. The same quantity of beets was treated per 24 hours,
and the general temperature remained the same. This remarkable result in
the saving of fuel was brought about notwithstanding the new apparatus
treated but a third, at the most, of the total amount of the juice, the
rest continuing to be concentrated by the double action process.

As for the running of the apparatus, that was perfectly regular, and the
deviations in temperature in each evaporater were scarcely two or three
degrees. The following are the mean temperatures:

First evaporator: heating steam 110° C.; juice steam 100° C. Second
evaporator: juice steam 83° C. Third evaporator: juice steam 62° C. As
regards facility of operating the apparatus, the experiment has proved
so conclusive that the plant will be considerably enlarged in view of
the coming crop, in order that a larger quantity of juice may be treated
by the new process. The effect of this will be to still further increase
the saving in coal that has already been effected by the present
apparatus. The engraving which accompanies this article represents the
Weibel-Piccard apparatus as it is now working in the Pohrlitz sugar
works. What we have said of it above we think will suffice to make it
understood without further explanation.--_Le Genie Civil_.

       *       *       *       *       *




COMPARISON OF STRENGTH OF LARGE AND SMALL ANIMALS.

W. N. LOCKINGTON.


M. Delebeuf, in a paper read before the Academie Royale de Belgique, and
published in the _Revue Scientique_, reviews the attempts of various
naturalists to make comparisons between the strength of large animals
and that of small ones, especially insects, and shows that ignorance or
forgetfulness of physical laws vitiates all their conclusions.

After a plea for the idea without which the fact is barren, M. Delbeuf
repeats certain statements with which readers of modern zoological
science are tolerably familiar, such as the following: A flea can jump
two hundred times its length; therefore a horse, were its strength
proportioned to its weight, could leap the Rocky Mountains, and a whale
could spring two hundred leagues in height. An Amazon ant walks about
eight feet per minute, but if the progress of a human Amazon were
proportioned to her larger size, she could stride over eight leagues in
an hour; and if proportioned to her greater weight, she would make the
circuit of the globe in about twelve minutes. This seems greatly to the
advantage of the insect. What weak creatures vertebrates must be, is the
impression conveyed.

But the work increases as the weight. In springing, walking, swimming,
or any other activity, the force employed has first to overcome the
weight of the body. A man can easily bound a height of two feet, and
he weighs as much as a hundred thousand grasshoppers, while a hundred
thousand grasshoppers could leap no higher than one--say a foot. This
shows that the vertebrate has the advantage. A man represents the volume
of fifteen millions of ants, yet can easily move more than three hundred
feet a minute, a comparison which gives him forty times more power, bulk
for bulk, than the ant possesses. Yet were all the conditions compared,
something like equality would probably be the result. Much of the force
of a moving man is lost from the inequalities of the way. His body,
supported on two points only when at rest, oscillates like a pendulum
from one to the other as he moves. The ant crawls close to the ground,
and has only a small part of the body unsupported at once. This
economizes force at each step, but on the other hand multiplies the
number of steps so greatly, since the smallest irregularity of the
surface is a hill to a crawling creature, that the total loss of force
is perhaps greater, since it has to slightly raise its body a thousand
times or so to clear a space spanned by a man's one step.

By what peculiarity of our minds do we seem to expect the speed of an
animal to be in proportion to its size? We do not expect a caravan to
move faster than a single horseman, nor an eight hundred pound shot to
move twelve thousand eight hundred times farther than an ounce ball.
Devout writers speak of a wise provision of Nature. "If," say they, "the
speed of a mouse were as much less than that of a horse as its body is
smaller, it would take two steps per second, and be caught at once."
Would not Nature have done better for the mouse had she suppressed the
cat? Is it not a fact that small animals often owe their escape to their
want of swiftness, which enables them to change their direction readily?
A man can easily overtake a mouse in a straight run, but the ready
change of direction baffles him.

M. Plateau has experimented on the strength of insects, and the facts
are unassailable. He has harnessed carabi, necrophori, June-beetles
(Melolontha), and other insects in such a way that, with a delicate
balance, he can measure their powers of draught. He announces the result
that the smallest insects are the strongest proportioned to their size,
but that all are enormously strong when compared bulk, for bulk, with
vertebrates. A horse can scarcely lift two-thirds of its own weight,
while one small species of June-beetle can lift sixty-six times its
weight; forty thousand such June-beetles could lift as much as a
draught-horse. Were our strength in proportion to this, we could play
with weights equal to ten times that of a horse.

This seems, again, great kindness in Nature to the smaller animal. But
all these calculations leave out the elementary mechanical law: "What
is gained in power is lost in time." The elevation of a ton to a given
height represents an expenditure of an equal amount of force, whether
the labor is performed by flea, man, or horse. Time supplies lack of
strength. We can move as much as a horse by taking more time, and can
choose two methods--either to divide the load or use a lever or a
pulley. If a horse moves half its own weight three feet in a second,
while a June-beetle needs a hundred seconds to convey fifty times
its weight an equal distance, the two animals perform equal work
proportioned to their weights. True, the cockchafer can hold fourteen
times its weight in equilibrium (one small June-beetle sixty-six times),
while a horse cannot balance nearly his own weight. But this does not
measure the amount of oscillatory motion induced by the respective
pulls. For this, both should operate against a spring.

A small beetle can escape from under a piece of cardboard a hundred
times its weight. Pushing its head under the edge and using it as a
lever, it straightens itself on its legs and moves the board just a
little, but enough to escape. Of course, we know a horse would be
powerless to escape from a load a hundred times its own weight. His head
cannot be made into a lever. Give him a lever that will make the time he
takes equal to that taken by the insect, and he will throw off the load
at a touch. The fact is that in small creatures the lack of muscular
energy is replaced by time.

Of two muscles equal in bulk and energy the shortest moves most weight.
If a muscular fiber ten inches in length can move a given weight five
inches, ten fibers one inch long will move ten times that weight a
distance of half an inch. Thus smaller muscles have an absolutely
slower motion, but move a greater proportional weight than larger.
The experimenter before mentioned was surprised to find that two
grasshoppers, one of which was three times the bulk of the other,
leaped an equal height. This was what might be expected of two animals
similarly constructed. The spring was proportioned to the bulk. In
experiments on the insects with powerful wings, such as bees, flies,
dragon-flies, etc., it was found that the weight they could bear without
being forced to descend was in most cases equal to their own. In some
cases it was more, but the inequality of rate of flight, had it been
taken into the reckoning, would have accounted for this.

Take two creatures of different bulk but built upon exactly the same
plan and proportions, say a Brobdingnagian and a Lilliputian, and let
both show their powers in the arena. Suppose the first to weigh a
million times more than the second. If the giant could raise to his
shoulder, some thirty-five feet from the ground, a weight twenty
thousand pounds, the dwarf can raise to his shoulder, not, as might be
thought, a fiftieth of a pound, but two full pounds. The distance raised
would be a hundred times less. In a race the Lilliputian, with a hundred
skips a second, will travel an equal distance with the giant, who would
take but a skip in a second. The leg of the latter weighs a million
times the most, but has only ten thousand times as many muscle fibers,
each a hundred times longer than those of the dwarf, who thus takes one
hundred skips while the giant takes one. The same physical laws apply to
all muscles, so that, when all the factors are considered, muscles of
the same quality have equal power.--_Am. Field._.

       *       *       *       *       *




OIL IN CALIFORNIA.


J.W. McKinley, writing to the Pittsburg _Dispatch_, gives the following
account of the California oil field at Newhall:

On the edge of the town is located the refinery of the company,
connected by pipe lines with the wells, a few miles distant. Leaving
Newhall, we drove to Pico Cañon, the principal producing territory of
the region. As we approached, we saw, away up on the peaks, the tall
derricks in places which looked inaccessible; but no spot is out of
reach of American enterprise and perseverance. In one of the wildest
spots of the cañon, about thirty men were making the mountains echo to
the strokes of their hammers upon the iron plates of a new 20,000 barrel
tank. Along the cañon are scattered the houses of the employes of the
company, most of whom have recently come from Pennsylvania. Near one of
the houses was a graded and leveled croquet ground, with a little oil
tank on a post, for lighting it at night. Farther up we came to a
cluster of producing wells, with others at a little distance on the
sides of the mountains, or even at the top, hundreds of feet above our
heads.

The first well was put down about eight years ago, but more has been
accomplished in the last two years than in all the time previous. One
well which we visited has produced 130,000 barrels in the last three
years, and is still yielding. There have been no very large wells, the
best being 250 per day, and the average being about 90 barrels, but they
keep up their production, with scarcely any diminution from year to
year. Drilling has been found difficult, as a great portion of the rock
is broken shale lying obliquely. The tools slip to one side very easily,
and a number of "crooked holes" have resulted. One driller lost his
tools altogether in a well, and finished it with new ones. The cost of
putting down a well is from $5,000 to $7,000, depending upon depth, etc.
Most of the wells are from 1,200 to 1,500 feet, but some have yielded at
a much less depth. One well of 270 feet depth produced 40 barrels per
day for about three years, has been deepened, and is now yielding even
more. Another one of 800 feet is said to have produced 200,000 barrels
in the last five or six years. Drilling has been very successful in
striking oil in paying quantities wherever there were indications of its
presence.

The Pacific Oil Company now has 27 wells producing or drilling, and
during the last two years has been rapidly widening the scope of its
operations. It has now from 30 to 40 miles of pipe lines, and is
preparing to lay 20 miles more, to connect its land with ocean shipping
at Ventura. The producers of California have a great advantage in their
proximity to the ocean, which gives them free commerce with the outside
world. Crude oil is now sold at $3 per barrel in Los Angeles, and the
oil companies are making immense profits. There is a very large amount
of oil territory as yet undeveloped, and a rich reward awaits enterprise
in these regions. In the Camulos District, which lies west of the San
Fernando, are even stronger surface indications of oil than there
were in the Pico Cañon. We first went up the Brea Cañon, in which are
numerous outbursts and springs of oil. Ascending the mountain west of
this cañon, we could plainly see the break in the mountains crossing
from the San Fernando through this district to those beyond which
have been developed. A couple of miles farther west, the Hooper Cañon
stretches back over two miles into the mountain, and is full of oil.
Great pools of oil fill its water courses, that are dry at present.
Hundreds of barrels of oil must be wasted away and evaporated during a
year. A well put down only 90 feet by horse power, struck light oil in
considerable quantity, and, had it not been for the death of one of the
owners and the consequent suspension of operations, would doubtless have
yielded in large quantities at the depth of a few hundred feet.

The mountainous territory between these two cañons will probably in a
few years be the scene of great activity. In the Little Sespe District,
a few miles west of Camulos, a 125 barrel well was struck at 1,500
feet recently. The Santa Paula region, a little farther west, is also
yielding large profits to the parties developing it.

       *       *       *       *       *




NUTRITIVE VALUE OF CONDIMENTS.

By HELEN D. ABBOTT, Assistant in the Chemical Laboratory of the
Philadelphia Polyclinic, and College for Graduates in Medicine.


The prevailing opinion respecting the substances known as condiments
is, that they possess essentially stimulating qualities, rendering them
peculiarly fitted for inducing, by reflex action, the secretion of the
alimentary juices. Letheby gives, as the functions of condiments,
such as pepper, mustard, spices, pot-herbs, etc., that besides their
stimulating properties they give flavor to food; and by them indifferent
food is made palatable, and its digestion accelerated. He enumerates as
aids to digestion--proper selection of food, according to the taste of
the individual, proper treatment of it as regards cooking, and proper
variation of it, both as to its nature and treatment.

While it is difficult to give an entirely satisfactory definition as to
what constitutes food, the following extracts from standard works
will serve as guides. Hermann[1] says: "The compound must be fit
for absorption into the blood or chyle, either directly, or after
preparation by the processes of digestion, i.e., it must be digestible.
It must replace directly some inorganic or organic constituent of the
body; or it must undergo conversion into such a constituent, while in
the body; or it must serve as an ingredient in the construction of such
a constituent." He further says that water, chlorides, and phosphates
are the most indispensable articles of diet. Watts[2] states that
"whatever is commonly absorbed in a state of health is perhaps the best,
or rather the truest, definition of food."

[Footnote 1: Elements of Human Physiology, by L. Hermann. Translated by
Gamgee.]

[Footnote 2: Dictionary of Chemistry, vol. iv., pages 147-8.]

Chemical analysis shows that the most important and widely applicable
foods contain carbon, hydrogen, oxygen, nitrogen, and mineral matter,
the latter containing phosphates and chlorides. Other things being
equal, it may be considered that the comparative nutrient value of
two articles is in proportion to the amounts of carbon, nitrogen, and
phosphoric acid they contain.

"The food of man also contains certain substances known under the name
of condiments. Since these bodies perform their functions outside the
real body, though within the alimentary canal, they have no
better reason to be considered as food than has hunger, _optimum
condimentum_."[1] Such is the positively expressed opinion of Foster,
the author of the article on nutrition in Watts' Dictionary of
Chemistry. With a view of determining how far the common condiments
deserve this summary dismissal, a number of analyses have been made in
the laboratory of the Philadelphia Polyclinic. My examinations were
especially directed to the mineral matter, phosphoric acid, and
nitrogen. The following table shows the result of the analyses:

                                 Percent.   Percent.
                                 of ash.    of P_{2}O_{5}.

  Fennel........................  9.00       .103
  Marjoram......................  8.84       .050
  Peppermint....................  8.80       .016
  Thyme.........................  8.34       .122
  Poppy.........................  7.74       .024
  Sage..........................  7.58       .033
  Caraway.......................  7.08       .118
  Spearmint.....................  7.06       .017
  Coriander.....................  6.10       .097
  Cloves........................  5.84       .563
  Allspice......................  5.54       .017
  Mustard.......................  3.90       .134
  Black pepper..................  3.60       .011
  Jamaica ginger................  3.16       .052
  Cinnamon......................  3.02       .009
  Mace..........................  2.44       .230
  Nutmeg........................  2.24       .092
  Celery........................  1.29       .082
  White pepper..................  1.16       .017
  Aniseed.......................  1.05       .113

[Footnote 1: Ibid., page 149.]

The articles were examined in the condition in which they were
obtained in the market, without any preliminary drying, selecting, or
preparation. The ash was obtained by burning in a platinum crucible, at
as low a temperature as possible, dissolving in hydrochloric acid the
phosphoric acid separated as ammonium molybdo-phosphate, and determined
in the usual manner.

Qualitative tests made for nitrogen indicated its presence in each one
of the condiments examined.

It is of importance to observe that the majority of these condiments are
fruits, ripe or nearly so. The seed appropriates to itself the nitrogen
and the greatest nutritive properties for the development of the future
plant. All nutritive substances fall into two classes: the one serves
for the repair of the unoxidizable constituents of the body, the other
is destined to replace the oxidizable. Condiments fulfill both of
these requirements, as is shown by a study of their composition; the
phosphoric acid and nitrogen are taken up by the tissues, as from other
substances used in diet. Some articles affect the character of the
excretions; this is often due to essential oils; the presence of these
in the excretions cannot be said to diminish the value of the substances
in supplying the tissues the necessary elements. The same holds true for
condiments; the essential oils conspicuous in them are accorded only
stimulating properties; however, it may be observed that the essential
oils in tea and coffee are accredited with a portion of the dietetic
value of these beverages. It appears that when condiments are used in
food, especially for the sick, they may serve the double purpose of
rendering the food more appetizing and of adding to its nutritive value.
The value of food as a purely therapeutic agent is attracting some
attention at present, and in its study we must not neglect
those substances which combine stimulant and nutritive
qualities.--_Polyclinic_.

       *       *       *       *       *

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