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SCIENTIFIC AMERICAN SUPPLEMENT NO. 443.




NEW YORK, JUNE 28, 1884.

Scientific American Supplement. Vol. XVII., No. 443.

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.    CHEMISTRY AND METALLURGY.--Beeswax and its Adulterations.
      --Chemical ingredients.--Detection of adulterations.        7064

      Phenol in the Stem, Leaves, and Cones of Pinus Sylvestris.
      --A discovery bearing on the flora of the Carboniferous
      epoch and the formation of petroleum.                       7065

      The School of Physics and Chemistry of Paris.--With
      engraving of laboratory.                                    7065

      Some Relations of Heat to Voltaic and Thermo Electric
      Action of Metals in Electrolysis.--By G. GORE.              7070

II.   ENGINEERING, MECHANICS, ETC.--Air Refrigerating
      Machine.--5 figures.                                        7071

      A Gas Radiator and Heater.                                  7071

      Concrete Water Pipes.                                       7071

      The Sellers Standard System of Screw Threads. Nuts, and
      Bolt Heads.--A table.                                       7072

      An English Railway Ferry Boat.--3 figures.                  7072

      The Problem of Flight and the Flying Machine.               7072

III.  TECHNICAL.--Concrete Buildings for Farms.--How to construct
      them.                                                       7063

      What Causes Paint to Blister and Peel?--How to prevent it.  7063

      Olive Oil.--Difficulties encountered in raising an olive
      crop.--Process of making Oil.                               7064

IV.   ELECTRICITY. ETC.--Telephony and Telegraphy on the Same
      Wires Simultaneously.--4 figures.                           7067

      The Electric Marigraph.--An apparatus for measuring the
      height of the tide.--With engravings and diagrams showing
      the Siemens and Halske marigraph and the operation of the
      same.                                                       7068

      Delune & Co.'s System of Laying Underground Cables.--2
      figures.                                                    7069

      Electricity Applied to Horseshoeing.--Quieting an unruly
      animal.--3 engravings.                                      7069

      Esteve's Automatic Pile.--1 figure.                         7070

      Woodward's Diffusion Motor.                                 7070

V.    ASTRONOMY.--Lunar Heat.--Its reflected and obscure
      heat.--Trifling influence of the moon upon wind and
      weather.--By Prof. C.A. YOUNG.                              7073

VI.   NATURAL HISTORY.--The Long-haired Pointer "Mylord."
      --With engraving.                                           7073

VII.  HORTICULTURE, ETC.--Apple Tree Borers.--Protection
      against the same.                                           7074

      Keffel's Germinating Apparatus.--With engraving.            7074

      Millet.--Its Cultivation.                                   7074

VIII. MISCELLANEOUS.--Puerta del Sol, Madrid, Spain.--With
      engraving.                                                  7063

      Dust-free Spaces.--A lecture delivered by Dr. OLIVER J.
      LODGE before the Royal Dublin Society.                      7067

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PUERTA DEL SOL, MADRID.


Puerta del Sol, or Gate of the Sun, Madrid, is the most famous and
favorite public square in the Spanish city of Madrid. It was the
eastern portal of the old city. From this square radiate several of
the finest streets, such as Alcala, one of the handsomest
thoroughfares in the world, Mayor, Martera, Carretas, Geronimo. In our
engraving the post office is seen on the right. Large and splendid
buildings adorn the other sides, which embrace hotels, cafes, reading
rooms, elegant stores, etc. From this square the street railway lines
traverse the city in all directions. The population of the city is
about 400,000. It contains many magnificent buildings. Our engraving
is from _Illustrirte Zeitung_.

[Illustration: THE PUERTA DEL SOL, MADRID, SPAIN (From a Photograph.)]

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CONCRETE BUILDINGS FOR FARMS.


Buildings made of concrete have never received the attention in this
country that they deserve. They have the merit of being durable and
fire-proof, and of not being liable to be blown down by violent winds.
It is very easy to erect them in places where sand and gravel are near
at hand and lime is comparatively cheap. Experiments made in England
show that coal screenings may be employed to good advantage in the
place of sand and gravel. Mr. Samuel Preston, of Mount Carroll, Ill.,
has a dwelling and several other buildings made of concrete and
erected by himself. They were put up in 1851, and are in excellent
condition. In _The Farmers' Review_ he gives the following directions
for building concrete walls:

First, secure a good stone foundation, the bottom below frost, the top
about one foot above ground. Near the top of the foundation bed in 2×4
scantling edgewise transversely with the walls, at such distances
apart as the length of the planks that form the boxes to hold the
concrete may require, the ends of the scantling to run six inches
beyond the outside and inside of the wall. Now take 2×6 studding, one
foot longer than the height of the concrete walls are to be, bolt in
an upright position in pairs to each end of the 2×4 scantling, and, if
a foot wall is to be built, sixteen inches apart, as the box plank
will take up four inches. To hold the studding together at the top,
take pieces of 2×6 lumber, make two mortises in each piece large
enough to slip easily up and down on the studding, forming a tie. Make
one mortise long enough to insert a key, so that the studding can be
opened at the top when the box plank are to be raised. When the box
plank are in position, nail cleats with a hole in each of them on each
side of the studding, and corresponding holes in the studding, into
which insert a pin to hold the plank to the studding. Bore holes along
up in the studding, to hold the boxes when raised.

To make the walls hollow, and I would do it in a building for any
purpose, use inch boards the same width of the box plank, one side
planed; put the two rough sides together with shingles between,
nailing them together with six-penny nails; place them in the middle
of the wall, the thin end of the shingle down. That gives them a bevel
and can be easily raised with the boxes. To tie the wall together, at
every third course place strips of boards a little shorter than the
thickness of the wall; cut notches in each so that the concrete will
fill in, holding all fast. The side walls being up, place two inch
planks on top of the wall upon which to rest the upper joists, put on
joist and rafters, remove the box plank, take inch boards for boxes,
cut to fit between joists and rafters, and fill with concrete to upper
side of rafters, which makes walls that will keep out cold and damp,
all kinds of vermin, and a roof which nothing but a cyclone can
remove. In making door and window frames, make the jambs two inches
narrower than the thickness of the walls, nailing on temporary two
inch strips.

Make the mortar bed large enough to hold the material for one course;
put in unslaked quicklime in proportion to 1 to 20 or 30 of other
material; throw into it plenty of water, and don't have that
antediluvian idea that you can drown it; put in clean sand and gravel,
broken stone, making it thin enough, so that when it is put into boxes
the thinner portion will run in, filling all interstices, forming a
solid mass. A brick trowel is necessary to work it down alongside the
boxing plank. One of the best and easiest things to carry the concrete
to the boxes is a railroad wheelbarrow, scooping it in with a scoop
shovel. Two courses a week is about as fast as it will be safe to lay
up the walls.

       *       *       *       *       *

The _Medical Summary_ recommends the external use of buttermilk to
ladies who are exposed to tan or freckles.

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WHAT CAUSES PAINT TO BLISTER AND PEEL?

HOW TO PREVENT IT.


This subject has been treated by many, but out of the numerous ideas
that have been brought to bear upon it, the writers have failed to
elucidate the question fully, probably owing to the fact that in most
parts they were themselves dubious as to the real cause. Last year
W.S. gave a lengthy description in the _Building News_, in which he
classified blistering and peeling of paint into one of blistering
only. He stated in the beginning of his treatise the following:

"The subject of blistering of paint has from time to time engrossed
the attention of practical men; but so far as we can follow it in the
literature pertaining to the building trade, its cause has never been
clearly laid down, and hence it is a detail enshrouded in mystery."

W.S. dwells mostly, in his following explanations on blistering
paints, on steam raised in damp wood. Also an English painter,
according to the _Painters' Journal_, lately reiterates the same
theory, and gives sundry reasons how water will get into wood through
paint, but is oblivious that the channels which lead water into wood
are open to let it out again. He lays great stress on boiled oil
holding water in suspense to cause blistering, which is merely a
conjecture. Water boils at 212° F. and linseed oil at 600° F.,
consequently no water can possibly remain after boiling, and a drop of
water put into boiling oil would cause an explosion too dangerous to
be encountered.

It will be shown herewith that boiled oil, though in general use, is
unfit for durable painting, that it is the cause of most of the
troubles painters have to contend with, and that raw linseed oil
seasoned by age is the only source to bind pigments for durable
painting; but how to procure it is another trouble to overcome, as all
our American raw linseed oil has been heated by the manufacturers, to
qualify it for quick drying and an early market, thereby impairing its
quality. After linseed oil has been boiled, it becomes a poor varnish;
it remains soft and pliable when used in paint, giving way to air
pressure from the wood in hot weather, forming blisters. Turpentine
causes no blistering; it evaporates upon being exposed, and leaves the
paint in a porous condition for the gas in the wood to escape; but all
painters agree that blistering is caused by gas, and on investigation
we find two main sources from which gas is generated to blister
paint--one from the wood, the other from the ingredients of the paint.
The first named source of gas is started in hot weather by expansion
of air confined in painted wood, which presses against the paint and
raises blisters when the paint is too soft to resist. Tough,
well-cemented paint resists the pressure and keeps the air back. These
blisters mostly subside as soon as the air cools and returns to the
pores, but subsequently peel off.

W.S. and others assert that damp in painted wood turns into steam when
exposed to sun heat, forming blisters, which cannot be possible when
we know that water does not take a gaseous form (steam) at less than
212° F. They have very likely been deluded by the known way of
distilling water with the aid of sunshine without concentrating the
rays of the sun, based upon the solubility of water in air, viz.: Air
holds more water in solution (or suspension) in a warmer than in a
cooler degree of temperature; by means of a simple apparatus
sun-heated air is guided over sun-heated water, when the air saturated
with water is conducted into a cooler, to give up its water again. But
water has an influence toward hastening to blister paint; it holds the
unhardened woodsap in solution, forming a slight solvent of the oil,
thereby loosening the paint from the wood, favoring blistering and
peeling. There is a certain kind of blister which appears in certain
spots or places only, and nowhere else, puzzling many painters. The
explanation of this is the same as before--soft paint at these spots,
caused by accident or sluggish workmen having saturated the wood with
coal oil, wax, tar, grease, or any other paint-softening material
before the wood was painted, which reacts on the paint to give way to
air pressure, forming blisters.

The second cause of paint blistering from the ingredients of the paint
happens between any layer of paint or varnish on wood, iron, stone, or
any other substance. Its origin is the gaseous formation of volatile
oils during the heated season, of which the lighter coal oils play the
most conspicuous part; they being less valuable than all other
volatile oils, are used in low priced japan driers and varnishes.
These volatile oils take a gaseous form at different temperatures, lie
partly dormant until the thermometer hovers at 90° F. in the shade,
when they develop into gas, forming blisters in airtight paint, or
escape unnoticed in porous paint. This is the reason why coal-tar
paint is so liable to blister in hot weather; an elastic, soft
coal-tar covering holds part of its volatile oil confined until heated
to generate into gas; a few drops only of such oil is sufficient to
spoil the best painted work, and worse, when it has been applied in
priming, it settles into the pores of the wood, needing often from two
to three repetitions of scraping and repainting before the evil is
overcome. Now, inasmuch as soft drying paint is unfit to answer the
purpose, it is equally as bad when paint too hard or brittle has been
used, that does not expand and contract in harmony with the painted
article, causing the paint to crack and peel off, which is always the
case when either oil or varnish has been too sparingly and turpentine
too freely used. Intense cold favors the action, when all paints
become very brittle, a fact much to be seen on low-priced vehicles in
winter time. Damp in wood will also hasten it, as stated in
blistering, the woodsap undermining the paint.

To avoid peeling and blistering, the paint should be mixed with raw
linseed oil in such proportions that it neither becomes too brittle
nor too soft when dry. Priming paint with nearly all oil and hardly
any pigment is the foundation of many evils in painting; it leaves too
much free oil in the paint, forming a soft undercoat. For durable
painting, paint should be mixed with as much of a base pigment as it
can possibly be spread with a brush, giving a thin coat and forming a
chemical combination called soap. To avoid an excess of oil, the
following coats need turpentine to insure the same proportion of oil
and pigment. As proof of this, prime a piece of wood and a piece of
iron with the same paint; when the wood takes up part of the oil from
the paint and leaves the rest in proportion to harden well, where at
the same time the paint on iron remains soft. To be more lucid, it
need be explained, linseed oil boiled has lost its oleic acid and
glycerine ether, which form with the bases of pigments the insoluble
soap, as well as its albumen, which in boiling is thrown out. It
coagulates at 160° F. heat; each is needed to better withstand the
action of wind and weather, preventing the dust from attaching itself
to a painted surface, a channel for ammonia in damp weather to
dissolve and wash off the paint. In later years linseed oil has been
extracted from linseed meal by the aid of naphtha and percolation, the
product of a very clear, quick drying oil, but lacking in its binding
quality, no doubt caused by the naphtha dissolving the fatty matter
only, leaving the glycerine and albumen in the meal.

All pigments of paint group according to their affinity to raw linseed
oil into three classes. First, those that form chemical combinations,
called soap. This kind is the most durable, is used for priming
purposes, and consists of lead, zinc, and iron bases, of which red
lead takes up the most oil; next, white lead, the pure carbonate Dutch
process made, following with zinc white and iron carbonates, as iron
ore paint, Turkey umber, yellow ocher; also faintly the chromates of
lead--chrome-green and chrome-yellow, finishing with the poorest of
all, modern white lead, made by the wet or vinegar process. The second
class being neutrals have no chemical affinity to linseed oil; they
need a large quantity of drier to harden the paint, and include all
blacks, vermilion, Prussian, Paris, and Chinese blue, also terra di
Sienna, Vandyke brown, Paris green, verdigris, ultramarine, genuine
carmine, and madderlake. The last seven are, on account of their
transparency, better adapted for varnish mixtures--glazing. The third
class of pigments act destructively to linseed oil; they having an
acid base (mostly tin salt, hydrochloride of tin, and redwood dye),
form with the gelatinous matter of the oil a jelly that will neither
work well under the brush nor harden sufficiently, and can be used in
varnish for glazing only; they are not permanent in color, and among
the most troublesome are the lower grades of so-called carmines,
madderlakes, rose pinks, etc., which contain more or less acidous
dyes, forming a soft paint with linseed oil that once dry on a job can
be twisted or peeled off like the skin of a ripe peach. All these
combinations of paint have to be closely observed by the painter to
insure his success.

Twenty-five years ago a house needed to be painted outside but once in
from five to seven years; it looked well all the time, as no dust
settled in the paint to make it unsightly. Painters then used the
Dutch-process-made white-lead, a base and raw linseed oil, a fat acid,
which formed the insoluble soap. They also put turpentine in the
following coats, to keep up the proportions of oil and pigment. All
held out well against wind and weather. Now they use the
wet-process-made white lead, neutralized by vinegar, with oil
neutralized by boiling, from the first to the last coat, and--fail in
making their work permanent.

W.S., in the _Building News_, relates an unaccountable mysterious
blistering in a leaky house, where the rainwater came from above on a
painted wood wall, blistering the paint in streaks and filled at the
lower ends with water, which no doubt was caused by the water soaking
the wood at the upper ends where there was no paint, and following it
down through the fibers, pushed and peeled off the soft, inadhesive
paint. Green, sappy, and resinous wood is unfit for durable painting,
and to avoid blistering and peeling wood should be well seasoned and
primed with all raw linseed oil, some drier, to insure a moderately
slow drying, and as much of a base pigment as the painter can possibly
spread (much drier takes up too much oil acid, needed for the pigment
base to combine with), which insures a tough paint that never fails to
stand against blistering or peeling, as well as wind, weather, and
ammonia.

The coach, car, and house painter can materially improve his painting
where his needs lie by first oiling the wood with raw oil, then
smoothing the surface down with lump pumicestone, washing it with a
mixture of japan drier or, better yet, gold sizing and turpentine,
wiping dry, and following it up with a coat of white lead, oil, and
turpentine. The explanation is: the raw oil penetrates the wood and
raises the wood fibers on the surface to be rubbed down with
pumicestone, insuring the best surface for the following painting: to
harden the oil in the wood it receives a coat of japan drier, which
follows into the pores and there forms a tough, resinous matter,
resisting any air pressure that might arise from within, and at the
same time reacts on the first coat of lead as a drier. This mode
insures the smoothest and toughest foundation for the following
painting, and may be exposed to the hottest July sun without fear of
either blistering or peeling.

LOUIS MATERN.

Bloomington, Ill.

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OLIVE OIL.


The following particulars with regard to the production of olive oil
in Tuscany have been furnished to Mr. Consul Inglis by one of the
principal exporters in Leghorn:

The olive oil produced in Tuscany from the first pressing of the fruit
is intended for consumption as an article of food. Hence, great
attention is paid both to the culture of the olive tree and the
process of making oil.

The olive crop is subject to many vicissitudes, and is an uncertain
one. It may be taken as a rule that a good crop does not occur more
frequently than once in three years. A prolonged drought in summer may
cause the greater part of the small fruit to fall off the trees. A
warm and wet autumn will subject the fruit to the ravages of a maggot
or worm, which eats its way into it. Fruit thus injured falls to the
ground prematurely, and the oil made from it is of very bad quality,
being nauseous in taste and somewhat thick and viscous. Frost
following immediately on a fall of snow or sleet, when the trees are
still wet, will irretrievably damage the fruit, causing it to shrivel
up and greatly diminishing the yield of oil, while the oil itself has
a dark color, and loses its delicate flavor.

The olive tree in Tuscany generally blossoms in April. By November the
fruit has attained its full size, though not full maturity, and the
olive harvest generally commences then. The fruit, generally speaking,
is gathered as it falls to the ground, either from ripeness or in
windy weather. In some districts, however, and when the crop is short,
the practice is to strip the fruit from the trees early in the season.
When there is a full crop the harvest lasts many months, and may not
be finished till the end of May, as the fruit does not all ripen
simultaneously.

Oil made early in the season has a deeper color, and is distinguished
by a fruity flavor, with a certain degree of pungency; while as the
season advances it becomes lighter in color, thinner in body, and
milder and sweeter in taste. Oil made toward the close of the harvest
in April or May from extremely ripe fruit is of a very pale straw
color, mild and sweet to the taste, though sometimes, if the fruit has
remained too long on the trees, it may be slightly rancid. Oil very
light in color is much prized in certain countries, notably France,
and hence, if it also possesses good quality, commands a higher price
in the Tuscan markets.

The fruit of the olive tree varies just as much in quality as does the
grape, according to the species of the tree itself, the nature of the
soil, exposure, and climate of the locality where it grows. Some
varieties of the olive tree largely grown, because thought to be
better suited to the special conditions of some districts, yield a
fruit which imparts a bitter taste to the oil made from it; such oil,
even when otherwise perfect, ranks as a second rate quality.

The highest quality of oil can only be obtained when the fruit is
perfectly and uniformly sound, well ripened, gathered as soon as it
has dropped from the trees, and crushed immediately with great
attention. Should the fruit remain any time on the ground,
particularly during wet weather, it deteriorates fast and gets an
earthy taste; while if allowed to remain an undue length of time in
the garners it heats, begins to decompose, and will yield only bad
oil.

The process of making oil is as follows: The fruit is crushed in a
stone mill, generally moved by water power; the pulp is then put into
bags made of fiber, and a certain number of these bags, piled one upon
another, are placed in a press, most frequently worked by hand; when
pressure is applied, the oil flows down into a channel by which it is
conveyed to a receptacle or tank.

When oil ceases to flow, tepid water is poured upon the bags to carry
off oil retained by the bags. The pulp is then removed from the bags,
ground again in the mill, then replaced in the bags, and pressed a
second time. The water used in the process of making oil must be quite
pure; the mill, press, bags, and vessels sweet and clean, as the least
taint would ruin the quality of the oil produced.

The oil which has collected in the tank or receptacle just mentioned
is removed day by day, and the water also drained off, as oil would
suffer in quality if left in contact with water; the water also, which
necessarily contains some oil mingled with it, is sent to a deposit
outside, and at some distance from the crushing house, which is called
the "Inferno," where it is allowed to accumulate, and the oil which
comes to the surface is skimmed off from time to time. It is fit only
for manufacturing purposes.

After the second pressing the olive-pulp is not yet done with; it is
beaten up with water by mechanical agitators moved by water-power, and
then the whole discharged into open-air tanks adjoining the crushing
house. There the crushed olive kernels sink to the bottom, are
gathered up and sold for fuel, fetching about 12 francs per 1,000
kilos, while the _debris_ of the pulp is skimmed off the surface of
the tank and again pressed in bags, yielding a considerable quantity
of inferior oil, called "olio lavato," or washed oil, which, if
freshly made, is even used for food by the poorer classes. The pulp
then remaining has still further use. It is sold for treatment in
factories by the sulphide of carbon process, and by this method yields
from seven to nine per cent. of oil, of course suitable only for
manufacturing purposes. Only the first two pressings yield oil which
ranks as first quality, subject of course to the condition of the
fruit being unexceptionable. New oil is allowed to rest a while in
order to get rid of sediment; it is then clarified by passing through
clean cotton wool, when it is fit for use.

The highest quality of olive oil for eating purposes should not only
be free from the least taint in taste or smell, but possessed of a
delicate, appetizing flavor. When so many favorable conditions are
needed as to growth, maturity, and soundness of the fruit, coupled
with great attention during the process of oil-making, it is not to be
wondered at that by no means all or even the greater part of the oil
produced in the most favored districts of Tuscany is of the highest
quality. On the contrary, the bulk is inferior and defective.

These defective oils are largely dealt in both for home consumption
and export, when price and not quality is the object.

In foreign countries there is always a market for inferior, defective
olive oil for cooking purposes, etc., provided the price be low. Price
and not quality is the object, so much so that when olive oil is dear,
cotton-seed, ground-nut, and other oils are substituted, which bear
the same relation to good olive oil that butterine and similar
preparations do to real butter.

The very choicest qualities of pure olive oil are largely shipped from
Leghorn to England, along with the very lowest qualities, often also
adulterated.

The oil put into Florence flasks is of the latter kind. Many years
back this was not the case, but now it is a recognized fact that
nothing but the lowest quality of oil is put into these flasks; oil
utterly unfit for food, and so bad that it is a mystery to what use it
is applied in England. Importers in England of oil in these flasks
care nothing, however, about quality; cheapness is the only
desideratum.

The best quality of Tuscan olive oil is imported in London in casks,
bottled there, and bears the name of the importers alone on the label.
There is no difficulty in procuring in England the best Tuscan oil,
which nothing produced elsewhere can surpass; but consumers who wish
to get, and are willing to pay for, the best article must look to the
name and reputation of the importers and the general excellence of all
the articles they sell, which is the best guarantee they can have of
quality.

       *       *       *       *       *




BEESWAX AND ITS ADULTERATIONS.


Beeswax is a peculiar waxy substance secreted only by bees, and
consisting of 80.2 per cent. carbon, 13.4 per cent. hydrogen, and 6.4
per cent. oxygen. It is a mixture of myricine, cerotic acid, and
cerolein, the first of which is insoluble in boiling alcohol, the
second is soluble in hot alcohol and crystallizes out on cooling,
while the third remains dissolved in cold alcohol.

Although we are unable to produce real beeswax artificially, there are
many imitations which are made use of to adulterate the genuine
article, and their detection is a matter of considerable difficulty.
Huebl says (_Dingl. Jour._, p. 338) that the most reliable method of
estimating the adulteration of beeswax is that proposed by Becker, and
known as the saponification method.

The quantity of potassic hydrate required to saponify one gramme or 15
grains of pure beeswax varies from 97 to 107 milligrammes. Other kinds
of wax and its substitutes require in some cases more and in others
less of the alkali. This method would, however, lead to very erroneous
conclusions if applied to a mixture of which some of the constituents
have higher saponification numbers than beeswax and others higher, as
one error would balance the other.

To avoid this, the quantity of alkali required to saponify the
myricine is first ascertained, and then that required to saturate the
free cerotic acid. In this way two numbers are obtained; and in an
investigation of twenty samples of Austrian yellow beeswax, the author
found these numbers stood to each other almost in the constant ratio
of 1 to 3.70. Although this ratio cannot be considered as definitely
established by so few experiments, it may serve as a guide in judging
of the purity of beeswax.

The experiment is carried out as follows: 3 or 4 grammes of the wax
that has been melted in water are put in 20 c.c. of neutral 95 per
cent, alcohol, and warmed until the wax melts, when phenolphthaleine
is added, and enough of an alcoholic solution of potash run in from a
burette until on shaking it retains a faint but permanent red color.
The burette used by the author is divided in 0.05 c.c. After adding 20
c.c. more of a half normal potash solution, it is heated on a water
bath for ¾ hour. Then the uncombined excess of alkali is titrated with
half normal hydrochloric acid. The alcohol must be tested as to its
reaction before using it, and carefully neutralized with the acid of
phenolphthalein.

To saturate the free acid in 1 gramme of wax requires 19 to 21
milligrammes of potassic hydrate, while 73 to 76 milligrammes more are
necessary to saponify the myricine ether. The lower numbers in the one
usually occur with low numbers for the other, so that the proportions
remain 1 to 3.6 or 1 to 3.8.

For comparison he gives the following numbers obtained with one gramme
of the more common adulterants:


  ----------------+----------+----------+---------+--------+
                  |    To    |    To    |  Total  |        |
                  |neutralize|  convert |saponifi-|        |
                  | the acid.|the ether.| cation. | Ratio. |
  ----------------+----------+----------+---------+--------+
  Japanese wax    |     20   |   200    |   220   |  10    |
  Carnauba wax    |      4   |    75    |    79   |  19    |
  Tallow          |      4   |   176    |   180   |  44    |
  Stearic acid    |    195   |     0    |   195   |  0/195 |
  Rosin           |    110   |     1.6  |   112   |  0.015 |
  Paraffine       |      0   |     0    |     0   |  0     |
  Ceresine        |      0   |     0    |     0   |  0     |
  Yellow beeswax  |     20   |    75    |    95   |  3.75  |
  ----------------+----------+----------+---------+--------+


The author deduces the following conclusions as the results of these
investigations:

1. If the numbers obtained lie between these limits, 19 to 21, 73 to
76, 92 to 97, and 3.6 to 3.8 respectively, it may be assumed that the
beeswax is pure, provided it also corresponds to beeswax in its
physical properties.

2. If the saponification figures fall below 92 and yet the ratio is
correct, it is adulterated with some neutral substance like paraffine.

3. If the ratio is above 3.8, it is very probable that Japanese or
carnauba wax or grease has been added.

4. If the ratio falls below 3.6, stearic acid or resin has been used
as the adulterant.

       *       *       *       *       *




PHENOL IN THE STEM, LEAVES, AND CONES OF PINUS SYLVESTRIS.

A DISCOVERY BEARING ON THE FLORA OF THE CARBONIFEROUS EPOCH AND THE
FORMATION OF PETROLEUM.

By A.B. GRIFFITHS, Ph.D., F.C.S. Membre de la Societe Chimique de
Paris, Medallist in Chemistry and Botany, etc.


Having found, in small quantities, alcohols of the C_{n}H_{2n-7}
series, last summer, in the stem, acicular leaves, and cones of _Pinus
sylvestris_, I wish in this paper to say a few words on the subject.

First of all, I took a number of cones, cut them up into small pieces,
and placed them in a large glass beaker, then nearly filled it with
distilled water, and heated to about 80° C., keeping the decoction at
this temperature for about half an hour, I occasionally stirred with a
glass rod, and then allowed it to cool, and filtered. This filtrate
was then evaporated nearly to dryness, when a small quantity of
six-sided prisms crystallized out, which subsequently were found to be
the hydrate of phenol (C_{6}H_{5}HO)_{2}H_{2}O. Its melting point was
found to be 17.2° C. Further, the crystals already referred to were
dissolved in ether, and then allowed to evaporate, when long colorless
needles were obtained, which, on being placed in a dry test tube and
the tube placed in a water bath kept at 42° C., were found to melt;
and on making a careful combustion analysis of these crystals, the
following composition was obtained:

                   Carbon     76.6
                   Hydrogen    6.4
                   Oxygen     17.0
                             -----
                             100.0

This gives C_{6}H_{6}O, which is the formula for phenol.

On dissolving some of these crystals in water (excess) and adding
ferric chloride, a beautiful violet color was imparted to the
solution. To another aqueous solution of the crystals was added
bromine water, and a white precipitate was obtained, consisting of
tribromophenol. An aqueous solution of the crystals immediately
coagulated albumen.

All these reactions show that the phenol occurs in the free state in
the cones of this plant. In the same manner I treated the acicular
leaves, and portions of the stem separately, both being previously cut
up into small pieces, and from both I obtained phenol.

I have ascertained the relative amount of phenol in each part of the
plant operated upon; by heating the stem with water at 80° C., and
filtering, and repeating this operation until the aqueous filtrate
gave no violet color with ferric chloride and no white precipitate
with bromine water.

I found various quantities according to the age of the stem. The older
portions yielding as much as 0.1021 per cent, while the young portions
only gave 0.0654 per cent. The leaves yielding according to their age,
0.0936 and 0.0315 per cent.; and the cones also gave varying amounts,
according to their maturity, the amounts varying between 0.0774 and
0.0293.

Two methods were used in the quantitative estimation of the amount of
phenol. The first was the new volumetric method of M. Chandelon
(_Bulletin de la Societe Chemique de Paris_, July 20, 1882; and
_Deutsch-Americanishe Apotheker Zeitung_, vol. iii., No. 12, September
1, 1882), which I have found to be very satisfactory. The process
depends on the precipitation of phenol by a dilute aqueous solution of
bromine as tribromophenol. The second method was to extract, as
already staled, a known weight of each part of the plant with water,
until the last extract gives _no_ violet color with ferric chloride,
and no white precipitate with the bromine test (which is capable of
detecting in a solution the 1/60000 part of phenol). The aqueous
extract is at this point evaporated, then ether is added, and finally
the ethereal solution is allowed to evaporate. The residue (phenol) is
weighed directly, and from this the percentage can be ascertained. By
this method of extraction, the oil of turpentine, resins, etc.,
contained in _Pinus sylvestris_ do not pass into solution, because
they are insoluble in water, even when boiling; what passes into
solution besides phenol is a little tannin, which is practically
insoluble in ether.

From this investigation it will be seen that phenol exists in various
proportions in the free state in the leaves, stem, and cones of _Pinus
sylvestris_, and as this compound is a product in the distillation of
coal, and as geologists have to a certain extent direct evidence that
the flora of the Carboniferous epoch was essentially crytogamous, the
only phænogamous plants which constituted any feature in "the coal
forests" being the coniferæ, and as coal is the fossil remains of that
gigantic flora which contained phenol, I think my discovery of phenol
in the coniferæ of the present day further supports, from a chemical
point of view, the views of geologists that the coniferæ existed so
far back in the world's history as the Carboniferous age.

I think this discovery also supports the theory that the origin of
petroleum in nature is produced by moderate heat on coal or similar
matter of a vegetable origin. For we know from the researches of
Freund and Pebal (_Ann. Chem. Pharm._, cxv. 19), that petroleum
contains phenol and its homologues, and as I have found this organic
compound in the coniferæ of to-day, it is probable that petroleum in
certain areas has been produced from the conifers and the flora
generally of some primæval forests. It is stated by numerous chemists
that "petroleum almost always contains solid paraffin" and similar
hydrocarbons. Professors Schorlemmer and Thorpe have found heptane in
Pinus, which heptane yielded primary heptyl-alcohol, and
methyl-pentyl-carbinol, exactly as the heptane obtained from petroleum
does (_Annalen de Chemie_, ccxvii., 139, and clxxxviii., 249; and
_Berichte der Deutschen Chemischen Gesellschaft_, viii., 1649); and,
further, petroleum contains a large number of hydrocarbons which are
found in coal. Again, Mendelejeff, Beilstein, and others (_Bulletin de
la Societe Chemique de Paris_, No. 1, July 5, 1883), have found
hydrocarbons of the--

             C_{n}H_{2n2+}, C_{n}H_{2n-6},

also hydrocarbons of the C_{n}H_{2n} series in the petroleum of Baku,
American petroleum containing similar hydrocarbons.

I think all these facts give very great weight to the theory that
petroleum is of organic origin.

On the other hand, Berthelot, from his synthetic production of
hydrocarbons, believes that the interior of the globe contains
alkaline metals in the _free_ state, which yield acetylides in the
presence of carbonic anhydride, which are decomposed into acetylene by
aqueous vapor. But it has been already proved that acetylene may be
polymerized, so as to produce aromatic carbides, or the derivatives of
marsh gas, by the absorption of hydrogen. Berthelot's view, therefore,
is too imaginative; for the presence of _free_ alkaline metals in the
earth's interior is an unproved and very improbable hypothesis.
Byasson states that petroleum is formed by the action of water,
carbonic anhydride, and sulphureted hydrogen upon incandescent iron.
Mendelejeff thinks it is formed by the action of aqueous vapor upon
carbides of iron; and in his article, "Petroleum, the Light of the
Poor" (in this month's--February--number of _Good Words_), Sir Lyon
Playfair, K.C.B., F.R.S., etc., holds opinions similar to those of
Mendelejeff.

Taking in consideration the facts that solid paraffin is found in
petroleum and is also found in coal, and from my own work that phenol
exists in _Pinus sylvestris_, and has been found by others in coal
which is produced from the decomposition of a flora containing
numerous gigantic coniferæ allied to Pinus, and that petroleum
contains phenol, and each (i.e., petroleum and coal) contains a number
of hydrocarbons common to both, I am inclined to think that the
balance of evidence is in favor of the hypothesis that petroleum has
been produced in nature from a vegetable source in the interior of the
globe. Of course, there can be no practical or direct evidence as to
the origin of petroleum; therefore "theories are the only lights with
which we can penetrate the obscurity of the unknown, and they are to
be valued just as far as they illuminate our path."

In conclusion, I think that there is a connecting link between the old
pine and fir forest of bygone ages and the origin of petroleum in
nature.--_Chemical News._

       *       *       *       *       *




THE SCHOOL OF PHYSICS AND CHEMISTRY OF PARIS.


Recently we paid a visit to the New Municipal School of Physics and
Chemistry that the city of Paris founded in 1882, and that is now in
operation in the large building of the old Rollin College. This
establishment is one of those that supply a long-felt want of our
time, and we are happy to make it known to our readers. The object for
which it was designed was, in the intention of its founders, to give
young people who have just graduated from the higher primary schools
special instruction which shall be at once scientific and practical,
and which shall fit them to become engineers or superintendents in
laboratories connected with chemical and physical industries. To reach
such a result it has been necessary to give the teaching an
essentially practical character, by permitting the pupils to proceed
of themselves in manipulations in well fitted laboratories. It is upon
this important point that we shall now more particularly dwell; but,
before making known the general mode of teaching, we wish to quote a
few passages from the school's official programme:

   "Many questions and problems, in physics as well as in chemistry,
   find their solution only with the aid of mathematics and
   mechanics. It therefore became necessary, through lectures
   bearing upon the useful branches of mathematics, to supplement
   the too limited ideas that pupils brought with them on entering
   the school. Mathematics and mechanics are therefore taught here
   at the same time with physics and chemistry, but they are merely
   regarded in the light of auxiliaries to the latter.

   "The studies extend over three years. Each of the three divisions
   (1st, 2d, and 3d years) includes thirty pupils.

   "During the three first semesters, pupils of the same grade
   attend lectures and go through manipulations in chemistry,
   physics, mathematics, and draughting in common.

   "At the end of the third semester they are divided into 10
   physical and 20 chemical students.

   "From this moment, although certain courses still remain wholly
   or partially common to the two categories of pupils (physical and
   chemical), the same is no longer the case with regard to the
   practical exercises, for the physical students thereafter
   manipulate only in the physical laboratories, and the chemical
   only in the chemical laboratories; moreover, the manipulations
   acquire a greater importance through the time that is devoted to
   them.

   "At each promotion the three first semesters are taken up with
   general and scientific studies. Technical applications are the
   subject of the lectures and exercises of the three last
   semesters. At the end of the third year certificates are given to
   those pupils who have undergone examination in a satisfactory
   manner, and diplomas to such as have particularly distinguished
   themselves."

When pupils have been received at the school, after passing the
necessary examination, their time of working is divided up between
lectures and questionings and different laboratory manipulations.

The course of lectures on general and applied physics comprises
hydrostatics and heat (Prof. Dommer), electricity and magnetism (Prof.
Hospitalier), and optics and acoustics (Prof. Baille). Lectures on
general chemistry are delivered by Profs. Schultzenberger and
Henninger, on analytical chemistry by Prof. Silva, on chemistry
applied to the industries by Prof. Henninger (for inorganic) and Prof.
Schultzenberger (for organic). The lectures on pure and applied
mathematics and mechanics are delivered by Profs. Levy and Roze.

[Illustration: GENERAL VIEW OF A LABORATORY AT THE PARIS SCHOOL OF
PHYSICS AND CHEMISTRY.]

The pupils occupy themselves regularly every day, during half the time
spent at the school, with practical work in analytical and applied
chemistry and physics and general chemistry. This practical work is a
complement to the various lectures, and has reference to what has been
taught therein. Once or twice per week the pupils spend three hours in
a shop devoted to wood and metal working, and learn how to turn,
forge, file, adjust, etc.

The school's cabinets are now provided with the best instruments for
study, and are daily becoming richer therein. The chemical
laboratories are none the less remarkably organized. In the
accompanying cut we give a view of one of these--the one that is under
the direction of Mr. Schultzenberger, professor of chemistry and
director of the new school. Each pupil has his own place in front of a
large table provided with a stand whereon he may arrange all the
products that he has to employ. Beneath the work-table he has at his
disposal a closet in which to place his apparatus after he is through
using them. Each pupil has in front of him a water-faucet, which is
fixed to a vertical column and placed over a sink. Alongside of this
faucet there is a double gas burner, which may be connected with
furnaces and heating apparatus by means of rubber tubing. A special
hall, with draught and ventilation, is set apart for precipitations by
sulphureted hydrogen and the preparation of chlorine and other
ill-smelling and deleterious gases. The great amount of light and
space provided secure the best of conditions of hygiene to this fine
and vast laboratory, where young people have all the necessary
requisites for becoming true chemists.--_La Nature._

       *       *       *       *       *




DUST-FREE SPACES.[1]

   [Footnote 1: Lecture to the Royal Dublin Society by Dr. Oliver J.
   Lodge, April 2, 1884.]


Within the last few years a singular interest has arisen in the
subject of dust, smoke, and fog, and several scientific researches
into the nature and properties of these phenomena have been recently
conducted. It so happened that at the time I received a request from
the secretary of this society to lecture here this afternoon I was in
the middle of a research connected with dust, which I had been
carrying on for some months in conjunction with Mr. J.W. Clark,
Demonstrator of Physics in University College, Liverpool, and which
had led us to some interesting results. It struck me that possibly
some sort of account of this investigation might not be unacceptable
to a learned body such as this, and accordingly I telegraphed off to
Mr. Moss the title of this afternoon's lecture. But now that the time
has come for me to approach the subject before you, I find myself
conscious of some misgivings, and the misgivings are founded upon this
ground: that the subject is not one that lends itself easily to
experimental demonstration before an audience. Many of the experiments
can only be made on a small scale, and require to be watched closely.
However, by help of diagrams and by not confining myself too closely
to our special investigation, but dealing somewhat with the wider
subject of dust in general, I may hope to render myself and my subject
intelligible if not very entertaining.

First of all, I draw no distinction between "dust" and "smoke." It
would be possible to draw such a distinction, but it would hardly be
in accordance with usage. Dust might be defined as smoke which had
settled, and the term smoke applied to solid particles still suspended
in the air. But at present the term "smoke" is applied to solid
particles produced by combustion only, and "dust" to particles owing
their floating existence to some other cause. This is evidently an
unessential distinction, and for the present I shall use either term
without distinction, meaning by dust or smoke, solid particles
floating in the air. Then "fog"; this differs from smoke only in the
fact that the particles are liquid instead of solid. And the three
terms dust, smoke, and fog, come to much the same thing, only that the
latter term is applied when the suspended particles are liquid. I do
not think, however, that we usually apply the term "fog" when the
liquid particles are pure water; we call it then mostly either mist or
cloud. The name "fog," at any rate in towns, carries with it the idea
of a hideous, greasy compound, consisting of smoke and mist and
sulphur and filth, as unlike the mists on a Highland mountain as a
country meadow is unlike a city slum. Nevertheless, the finest cloud
or mist that ever existed consists simply of little globules of water
suspended in air, and thus for our present purpose differs in no
important respect from fog, dust, and smoke. A cloud or mist is, in
fact, fine water-dust. Rain is coarse water-dust formed by the
aggregation of smaller globules, and varying in fineness from the
Scotch mist to the tropical deluge. It has often been asked how it is
that clouds and mists are able to float about when water is so much
heavier (800 times heavier) than air. The answer to this is easy. It
depends on the resistance or viscosity of fluids, and on the smallness
of the particles concerned. Bodies falling far through fluids acquire
a "terminal velocity," at which they are in stable equilibrium--their
weight being exactly equal to the resistance--and this terminal
velocity is greater for large particles than for small; consequently
we have all sorts of rain velocity, depending on the size of the
drops; and large particles of dust settle more quickly than small.
Cloud-spherules are falling therefore, but falling very slowly.

To recognize the presence of dust in air there are two principal
tests; the first is, the obvious one of looking at it with plenty of
light, the way one is accustomed to look for anything else; the other
is a method of Mr. John Aitken's, viz., to observe the condensation of
water vapor.

Take these in order. When a sunbeam enters a darkened room through a
chink, it is commonly said to be rendered visible by the motes or dust
particles dancing in it; but of course really it is not the motes
which make the sunbeam visible, but the sunbeam the motes. A dust
particle is illuminated like any other solid screen, and is able to
send a sufficient fraction of light to our eyes to render itself
visible. If there are no such particles in the beam--nothing but
clear, invisible air--then of course nothing is seen, and the beam
plunges on its way quite invisible to us unless we place our eyes in
its course. In other words, to be visible, light must enter the eye.
(A concentrated beam was passed through an empty tube, and then
ordinary air let in.)

The other test, that of Mr. Aitken, depends on the condensation of
steam. When a jet of steam finds itself in dusty air, it condenses
around each dust particle as a nucleus, and forms the white visible
cloud popularly called steam. In the absence of nuclei Mr. Aitken has
shown that the steam cannot condense until it is highly
supersaturated, and that when it does it condenses straight into
rain--that is, into large drops which fall. The condensation of steam
is a more delicate test for dust than is a beam of light. A curious
illustration of the action of nuclei in condensing moisture has just
occurred to me, in the experiment--well known to children--of writing
on a reasonably clean window-pane with, say, a blunt wooden point, and
then breathing on the glass; the condensation of the breath renders
the writing legible. No doubt the nuclei are partially wiped away by
the writing, and the moisture will condense into larger drops with
less light-scattering power along the written lines than over the
general surface of the pane where the nuclei are plentiful, and the
drops therefore numerous and minute. Mr. Aitken points out that if the
air were ever quite dustless, vapor could not condense, but the air
would gradually get into a horribly supersaturated condition, soaking
all our walls and clothes, dripping from every leaf, and penetrating
everywhere, instead of falling in an honest shower, against which
umbrellas and slate roofs are some protection. But let us understand
what sort of dust it is which is necessary for this condensing
process. It is not the dust and smoke of towns, it is not the dust of
a country road; all such particles as these are gross and large
compared with those which are able to act as condensers of moisture.
The fine dust of Mr. Aitken exists everywhere, even in the upper
regions of the atmosphere; many of its particles are of
ultra-microscopic fineness, one of them must exist in every raindrop,
nay, even in every spherule of a mist or cloud, but it is only
occasionally that one can find them with the microscope. It is to such
particles as these that we owe the blue of the sky, and yet they are
sufficiently gross and tangible to be capable of being filtered out of
the air by a packed mass of cotton-wool. Such dust as this, then, we
need never be afraid of being without. Without it there could be no
rain, and existence would be insupportable, perhaps impossible; but it
is not manufactured in towns; the sea makes it; trees and wind make
it; but the kind of dust made in towns rises only a few hundred yards
or so into the atmosphere, floating as a canopy or pall over those
unfortunate regions, and sinks and settles most of it as soon as the
air is quiet, but scarcely any of it ever rises into the upper regions
of the atmosphere at all.

Dust, then, being so universally prevalent, what do I mean by
dust-free spaces? How are such things possible? And where are they to
be found? In 1870 Dr. Tyndall was examining dusty air by means of a
beam of light in which a spirit-lamp happened to be burning, when he
noticed that from the flame there poured up torrents of apparently
thick black smoke. He could not think the flame was really smoky, but
to make sure he tried, first a Bunsen gas flame and then a hydrogen
flame. They all showed the same effect, and smoke was out of the
question. He then used a red-hot poker, a platinum wire ignited by an
electric current, and ultimately a flask of hot water, and he found
that from all warm bodies examined in dusty air by a beam of light the
upstreaming convection currents were dark. Now, of course smoke would
behave very differently. Dusty air itself is only a kind of smoke, and
it looks bright, and the thicker the smoke the brighter it looks; the
blackness is simply the utter absence of smoke; there is nothing at
all for the light to illuminate, accordingly we have the blankness of
sheer invisibility. Here is a flame burning under the beam, and, to
show what real smoke looks like, I will burn also this spirit lamp
filled with turpentine instead of alcohol. _Why_ the convention
currents were free from dust was unknown; Tyndall thought the dust was
burnt and consumed; Dr. Frankland thought it was simply evaporated.

In 1881 Lord Rayleigh took the matter up, not feeling satisfied with
these explanations, and repeated the experiment very carefully. He
noted several new points, and hit on the capital idea of seeing what a
cold body did. From the cold body the descending current was just as
dark and dust-free as from a warm body. Combustion and evaporation
explanations suffered their death-blow. But he was unable to suggest
any other explanation in their room, and so the phenomenon remained
curious and unexplained.

In this state Mr. Clark and I took the matter up last summer, and
critically examined all sorts of hypotheses that suggested themselves,
Mr. Clark following up the phenomena experimentally with great
ingenuity and perseverance. One hypothesis after another suggested
itself, seemed hopeful for a time, but ultimately had to be discarded.
Some died quickly, others lingered long. In the examination of one
electrical hypothesis which suggested itself we came across various
curious phenomena which we hope still to follow up.[2] It was some
months before what we now believe to be the true explanation began to
dawn upon us. Meanwhile we had acquired various new facts, and first
and foremost we found that the dark plane rising from a warm body was
only the upstreaming portion of a dust-free _coat_ perpetually being
renewed on the surface of the body. Let me describe the appearance and
mode of seeing it by help of a diagram. (For full description see
_Philosophical Magazine_ for March, 1884.)

   [Footnote 2: For instance, the electric properties of crystals
   can be readily examined in illuminated dusty air; the dust grows
   on them in little bushes and marks out their poles and neutral
   regions, without any need for an electrometer. Magnesia smoke
   answers capitally.]

Surrounding all bodies warmer than the air is a thin region free from
dust, which shows itself as a dark space when examined by looking
along a cylinder illuminated transversely, and with a dark background.
At high temperatures the coat is thick; at very low temperatures it is
absent, and dust then rapidly collects on the rod. On a warm surface
only the heavy particles are able to settle--there is evidently some
action tending to drive small bodies away. An excess of temperature of
a degree or two is sufficient to establish this dust-free coat, and it
is easy to see the dust-free plane rising from it. The appearances may
also be examined by looking along a cylinder _toward_ the source of
light, when the dust-free spaces will appear brighter than the rest. A
rod of electric light carbon warmed and fixed horizontally across a
bell-jar full of dense smoke is very suitable for this experiment, and
by means of a lens the dust-free regions may be thus projected on to a
screen. Diminished pressure makes the coat thicker. Increased pressure
makes it thinner. In hydrogen it is thicker, and in carbonic acid
thinner, than in air. We have also succeeded in observing it in
liquids--for instance, in water holding fine rouge in suspension, the
solid body being a metal steam tube. Quantitative determinations are
now in progress.

[Illustration: Fig. 1 and Fig. 2]

Fig. 1 shows the appearance when looking along a copper or carbon rod
laterally illuminated; the paths of the dust particles are roughly
indicated. Fig. 2 shows the coat on a semi-cylinder of sheet copper
with the concave side turned toward the light.

It is difficult to give the full explanation of the dust free spaces
in a few words, but we may say roughly that there is a molecular
bombardment from all warm surfaces by means of which small suspended
bodies get driven outward and kept away from the surface. It is a sort
of differential bombardment of the gas molecules on the two faces of a
dust particle somewhat analogous to the action on Mr. Crookes'
radiometer vanes. Near cold surfaces the bombardment is very feeble,
and if they are cold enough it appears to act toward the body, driving
the dust inward--at any rate, there is no outward bombardment
sufficient to keep the dust away, and bodies colder than the
atmosphere surrounding them soon get dusty. Thus if I hold this piece
of glass in a magnesium flame, or in a turpentine or camphor flame, it
quickly gets covered with smoke--white in the one case, black in the
other. I take two conical flasks with their surfaces blackened with
camphor black, and filling one with ice, the other with boiling water,
I cork them and put a bell jar over them, under which I burn some
magnesium wire; in a quarter of an hour or so we find that the cold
one is white and hoary, the hot one has only a few larger specks of
dust on it, these being of such size that the bombardment was unable
to sustain their weight, and they have settled by gravitation. We thus
see that when the air in a room is warmer than the solids in it--as
will be the case when stoves, gas-burners, etc., are used--things will
get very dusty; whereas when walls and objects are warmer than the
air--as will be the case in sunshine, or when open fireplaces are
used, things will tend to keep themselves more free from dust. Mr.
Aitken points out that soot in a chimney is an illustration of this
kind of deposition of dust; and as another illustration it strikes me
as just possible that the dirtiness of snow during a thaw may be
partly due to the bombardment on to the cold surface of dust out of
the warmer air above. Mr. Aitken has indeed suggested a sort of
practical dust or smoke filter on this principle, passing air between
two surfaces--one hot and one cold--so as to vigorously bombard the
particles on to the cold surface and leave the air free.

But we have found another and apparently much more effectual mode of
clearing air than this. We do it by discharging electricity into it.
It is easily possible to electrify air by means of a point or flame,
and an electrified body has this curious property, that the dust near
it at once aggregates together into larger particles. It is not
difficult to understand why this happens; each of the particles
becomes polarized by induction, and they then cling together end to
end, just like iron filings near a magnet. A feeble charge is often
sufficient to start this coagulating action. And when the particles
have grown into big ones, they easily and quickly fall. A stronger
charge forcibly drives them on to all electrified surfaces, where they
cling. A fine water fog in a bell jar, electrified, turns first into a
coarse fog or Scotch mist, and then into rain. Smoke also has its
particles coagulated, and a space can thus be cleared of it. I will
illustrate this action by making some artificial fogs in a bell-jar
furnished with a metal point. First burn some magnesium wire,
electrify it by a few turns of this small Voss machine, and the smoke
has become snow; the particles are elongated, and by pointing to the
charged rod indicate the lines of electrostatic force very
beautifully; electrify further, and the air is perfectly clear. Next
burn turpentine, and electrify gently; the dense black smoke
coagulates into black masses over an inch long; electrify further, and
the glass is covered with soot, but the air is clear. Turpentine smoke
acts very well, and can be tried on a larger scale; a room filled with
turpentine smoke, so dense that a gas-light is invisible inside it,
begins to clear in a minute or two after the machine begins to turn,
and in a quarter of an hour one can go in and find the walls thickly
covered with stringy blacks, notably on the gas-pipes and everything
most easily charged by induction. Next fill a bell-jar full of steam,
and electrify, paying attention to insulation of the supply point in
this case. In a few seconds the air looks clear, and turning on a beam
of light we see the globules of water dancing about, no longer fine
and impalpable, but separately visible and rapidly falling. Finally,
make a London fog by burning turpentine and sulphur, adding a little
sulphuric acid, either directly as vapor or indirectly by a trace of
nitric oxide, and then blowing in steam. Electrify, and it soon
becomes clear, although it lakes a little longer than before; and on
removing the bell-jar we find that even the smell of SO2 has
disappeared, and only a little vapor of turpentine remains. Similarly
we can make a Widnes fog by sulphureted hydrogen, chlorine, sulphuric
acid, and a little steam. Probably the steam assists the clearing when
gases have to be dealt with. It may be possible to clear the air of
tunnels by simply discharging electricity into the air--the
electricity being supplied by Holtz machines, driven say by small
turbines--a very handy form of power, difficult to get out of order.
Or possibly some hydro-electric arrangement might be devised for the
locomotive steam to do the work. I even hope to make some impression
on a London fog, discharging from lightning conductors or captive
balloons carrying flames, but it is premature to say anything about
this matter yet. I have, however, cleared a room of smoke very quickly
with a small hand machine.

It will naturally strike you how closely allied these phenomena must
be to the fact of popular science that "thunder clears the air." Ozone
is undoubtedly generated by the flashes, and may have a beneficial
effect, but the dust-coagulating and dust-expelling power of the
electricity has a much more rapid effect, though it may not act till
the cloud is discharged. Consider a cloud electrified slightly; the
mists and clouds in its vicinity begin to coagulate, and go on till
large drops are formed, which may be held up by electrical action, the
drops dancing from one cloud to another and thus forming the very
dense thunder cloud. The coagulation of charged drops increases the
potential, as Prof. Tait points out, until at length--flash--the cloud
is discharged, and the large drops fall in a violent shower. Moreover,
the rapid excursion to and fro of the drops may easily have caused
them to evaporate so fast as to freeze, and hence we may get hail.

While the cloud was electrified, it acted inductively on the earth
underneath, drawing up an opposite charge from all points, and thus
electrifying the atmosphere. When the discharge occurs this
atmospheric electrification engages with the earth, clearing the air
between, and driving the dust and germs on to all exposed surfaces. In
some such way also it may be that "thunder turns milk sour," and
exerts other putrefactive influences on the bodies which receive the
germs and dust from the air.

But we are now no longer on safe and thoroughly explored territory. I
have allowed myself to found upon a basis of experimental fact, a
superstructure of practical application to the explanation of the
phenomena of nature and to the uses of man. The basis seems to me
strong enough to bear most of the superstructure, but before being
sure it will be necessary actually to put the methods into operation
and to experiment on a very large scale. I hope to do this when I can
get to a suitable place of operation. Liverpool fogs are poor affairs,
and not worth clearing off. Manchester fogs are much better and more
frequent, but there is nothing to beat the real article as found in
London, and in London if possible I intend to rig up some large
machines and to see what happens. The underground railway also offers
its suffocating murkiness as a most tempting field for experiment, and
I wish I were able already to tell you the actual result instead of
being only in a position to indicate possibilities. Whether anything
comes of it practically or not, it is an instructive example of how
the smallest and most unpromising beginnings may, if only followed up
long enough, lead to suggestions for large practical application. When
we began the investigation into the dust-free spaces found above warm
bodies, we were not only without expectation, but without hope or idea
of any sort, that anything was likely to come of it; the phenomenon
itself possessed its own interest and charm.

And so it must ever be. The devotee of pure science never has
practical developments as his primary aim; often he not only does not
know, but does not in the least care whether his researches will ever
lead to any beneficial result. In some minds this passive ignoring of
the practical goes so far as to become active repulsion; so that some
singularly biased minds will not engage in anything which seems likely
to lead to practical use. I regard this as an error, and as the sign
of a warped judgment, for after all man is to us the most important
part of nature; but the system works well nevertheless, and the
division of labor accomplishes its object. One man investigates nature
impelled simply by his own genius, and because he feels he cannot help
it; it never occurs to him to give a reason for or to justify his
pursuits. Another subsequently utilizes his results, and applies them
to the benefit of the race. Meanwhile, however, it may happen that the
yet unapplied and unfruitful results evoke a sneer, and the question:
"Cui bono?" the only answer to which question seems to be: "No one is
wise enough to tell beforehand what gigantic developments may not
spring from the most insignificant fact."

       *       *       *       *       *




TELEPHONY AND TELEGRAPHY ON THE SAME WIRES SIMULTANEOUSLY.


For the last eighteen months a system has been in active operation in
Belgium whereby the ordinary telegraph wires are used to convey
telephonic communications at the same time that they are being
employed in their ordinary work of transmitting telegraphic messages.
This system, the invention of M. Van Rysselberghe, whose previous
devices for diminishing the evil effects of induction in the telephone
service will be remembered, has lately been described in the _Journal
Telegraphique_ of Berne, by M.J. Banneux of the Belgian Telegraph
Department. Our information is derived from this article and from
others by M. Hospitalier.

The method previously adopted by Van Rysselberghe, to prevent
induction from taking place between the telegraph wires and those
running parallel to them used for telephone work, was briefly as
follows: The system of sending the dots and dashes of the
code--usually done by depressing and raising a key which suddenly
turns on the current and then suddenly turns it off--was modified so
that the current should rise gradually and fall gradually in its
strength by the introduction of suitable resistances. These were
introduced into the circuit at the moment of closing or opening by a
simple automatic arrangement worked exactly as before by a key. The
result, of the gradual opening and gradual closing of the circuit was
that the current attained its full strength gradually instead of
suddenly, and died away also gradually. And as induction from one wire
to another depends not on the strength of the current, but on the rate
at which the strength changes, this very simple modification had the
effect of suppressing induction. Later Van Rysselberghe changed these
arrangements for the still simpler device of introducing permanently
into the circuit either condensers or else electro-magnets having a
high coefficient of self-induction. These, as is well known to all
telegraphic engineers, retard the rise or fall of an electric current;
they fulfill the conditions required for the working of Van
Rysselberghe's method better than any other device.

Having got thus far in his devices for destroying induction from one
line to another, Van Rysselberghe saw that, as an immediate
consequence, it might be concluded that, if the telegraph currents
were thus modified and graduated so that they produced no induction in
a neighboring telephone line, they would produce no sound in the
telephone if that instrument were itself joined up in the telegraph
line. And such was found to be case. Why this is so will be more
readily comprehended if it be remembered that a telephone is sensitive
to the changes in the strength of the current if those changes occur
with a frequency of some hundreds or in some cases thousands of times
_per second_. On the other hand, currents vibrating with such rapidity
as this are utterly incompetent to affect the moving parts of
telegraphic instruments, which cannot at the most be worked so as to
give more than 200 to 800 separate signals _per minute_.

[Illustration: Fig. 1]

[Illustration: Fig. 2]

The simplest arrangement for carrying out this method is shown in Fig.
1, which illustrates the arrangements at one end of a line. M is the
Morse key for sending messages, and is shown as in its position of
rest for receiving. The currents arriving from the line pass first
through a "graduating" electromagnet, E2, of about 500 ohms
resistance, then through the key, thence through the electromagnet, R,
of the receiving Morse instrument, and so to the earth. A condenser,
C, of 2 microfarads capacity is also introduced between the key and
earth. There is a second "graduating" electromagnet, E1, of 500 ohms
resistance introduced between the sending battery, B, and the key.
When the key, M, is depressed in order to send a signal, the current
from the battery must charge the condenser, C, and must magnetize the
cores of the two electromagnets, E1 and E2, and is thereby retarded in
rising to its full strength. Consequently no sound is heard in a
telephone, T, inserted in the line-circuit. Neither the currents which
start from one end nor those which start from the other will affect
the telephones inserted in the line. And, if these currents do not
affect telephones in the actual line, it is clear that they will not
affect telephones in neighboring lines. Also the telephones so
inserted in the main line might be used for speaking to one another,
though the arrangement of the telephones in the same actual line would
be inconvenient. Accordingly M. Van Rysselberghe has devised a further
modification in which a separate branch taken from the telegraph line
is made available for the telephone service. To understand this
matter, one other fact must be explained. Telephonic conversation can
be carried on, even though the actual metallic communication be
severed by the insertion of a condenser. Indeed, in quite the early
days of the Bell telephone, an operator in the States used a condenser
in the telegraph line to enable him to talk through the wire. If a
telephonic set at T1 (Fig. 2) communicate through the line to a
distant station, T2, through a condenser, C, of a capacity of half a
microfarad, conversation is still perfectly audible, provided the
telephonic system is one that acts by induction currents. And since in
this case the interposition of the condenser prevents any continuous
flow of current through the line, no perceptible weakening will be
felt if a shunt S, of as high a resistance as 500 ohms and of great
electromagnetic rigidity, that is to say, having a high coefficient of
self-induction, be placed across the circuit from line to earth. In
this, as well as in the other figures, the telephones indicated are of
the Bell pattern, and if set up as shown in Fig. 2, without any
battery, would be used both as transmitter and receiver on Bell's
original plan. But as a matter of fact any ordinary telephone might be
used. In practice the Bell telephone is not advantageous as a
transmitter, and has been abandoned except for receiving; the Blake,
Ader, or some other modification of the microphone being used in
conjunction with a separate battery. To avoid complication in the
drawings, however, the simplest case is taken. And it must be
understood that instead of the single instrument shown at T1 or T2, a
complete set of telephonic instruments, including transmitter,
battery, induction-coil, and receiver or receivers, may be
substituted. And if a shunt, S, of 500 ohms placed across the circuit
makes no difference to the talking in the telephones because of the
interposition of the separating condenser, C, it will readily be
understood that a telegraphic system properly "graduated," and having
also a resistance of 500 ohms, will not affect the telephones if
interposed in the place of S. This arrangement is shown in Fig. 3,
where the "graduated" telegraph-set from Fig. 1 is intercalated into
the telephonic system of Fig. 2, so that both work simultaneously, but
independently, through a single line. The combined system at each end
of the line will then consist of the telephone-set, T1, the telegraph
instruments (comprising battery, B1, key, M1 and Morse receiver, R1),
the "graduating" electromagnets, E1, and E2, the "graduating"
condenser, C1, and the "separating" condenser, C2. It was found by
actual experiments that the same arrangement was good for lines
varying from 28 to 200 miles in length. A single wire between
Brussels, Ghent, and Ostend is now regularly employed for transmission
by telegraph of the ordinary messages and of the telemeteorographic
signals between the two observatories at those places, and by
telephone of verbal simultaneous correspondence, for one of the Ghent
newspapers. A still more interesting arrangement is possible, and is
indicated in Fig. 4. Here a separating condenser is introduced at the
intermediate station at Ghent between earth and the line, which is
thereby cut into two independent sections for telephonic purposes,
while remaining for telegraphic purposes a single undivided line
between Brussels and Ostend. Brussels can telegraph to Ostend, or
Ostend to Brussels, and at the same time the wire can be used to
telephone between Ghent and Ostend, or between Ghent and Brussels, or
both sections may be simultaneously used.

[Illustration: Fig. 3]

[Illustration: Fig. 4]

It would appear, then, that M. Van Rysselberghe has made an advance of
very extraordinary merit in devising these combinations. We have seen
in recent years how duplex telegraphy superseded single working, only
to be in turn superseded by the quadruplex system. Multiplex
telegraphy of various kinds has been actively pursued, but chiefly on
the other side of the Atlantic rather than in this country, where our
fast-speed automatic system has proved quite adequate hitherto.
Whether we shall see the adoption in the United Kingdom of Van
Rysselberghe's system is, however, by no means certain. The essence of
it consists in retarding the telegraphic signals to a degree quite
incompatible with the fast-speed automatic transmission of telegraphic
messages in which our Post Office system excels. We are not likely to
spoil our telegraphic system for the sake of simultaneous telephony,
unless there is something to be gained of much greater advantage than
as yet appears.--_Nature._

       *       *       *       *       *




THE ELECTRIC MARIGRAPH.


For registering the height of the tide at every instant, hydrographic
services generally adopt quite a simple marigraph. The apparatus
consists in principle of a counterpoised float whose rising and
falling motion, reduced to a tenth, by means of a system of toothed
wheels, is transmitted to a pencil which moves in front of a vertical
cylinder. This cylinder itself moves around its axis by means of a
clockwork mechanism, and accomplishes one entire revolution every
twenty-four hours. By this means is obtained a curve of the tide in
which the times are taken for abscisses and the heights of the sea for
ordinates. However little such marigraphs have had to be used, great
defects have been recognized in them. When we come to change the sheet
on the cylinder (and such change should be made at least once every
fifteen days), there is an interruption in the curve. It is necessary,
besides, to perform office work of the most detailed kind in order to
refer to the same origin all these curves, which are intercrossed and
often superposed in certain parts upon the original sheet. In order to
render such a disentanglement possible, it is indispensable to mark by
hand, at least once every twenty-four hours, upon each curve, the date
of the day corresponding to it. It is equally useful to verify the
exactness of the indications given by the apparatus by making readings
several times a day on a scale of tides placed alongside of the float.
Nine times out of ten the rise of the waves renders such readings very
difficult and the control absolutely illusory.

All these conditions united, as well as others that we neglect in this
brief discussion, necessitate a surveillance at every instant. The
result is that these marigraphs must be installed in a special
structure, very near the bank, so as to be reachable at all times, and
that the indications that they give are always vitiated by error,
since the operation is performed upon a level at which are exerted
disturbing influences that are not found at a kilometer at sea. It
were to be desired that the float could be isolated by placing it a
certain distance from the shore, and transmit its indications, by
meant of a play of currents, to a registering apparatus situated upon
_terra firma_.

In the course of one of his lectures published in the December number
(1883) of the _Elektrotechnische Zeitschrift_, Mr. Von Hefner-Alteneck
tells us that such a desideratum has been supplied by the firm of
Siemens & Halske. This marigraph, constructed on an order of the
German Admiralty, gives the level of the sea every ten minutes with an
approximation of 0.12 per cent., and that too for a difference of 8
meters between the highest and lowest sea. The apparatus consists, as
we said above, of a float and registering device, connected with each
other by means of a cable. This latter is formed of three ordinary
conductors covered with gutta percha and surrounded with a leaden
sheath, which latter is itself protected against accident by means of
a strong covering of iron wire and hemp. The return is effected
through the earth. We shall enter into details concerning each of
these two apparatus in-succession, by beginning with the float, of
which Fig. 1 gives a general view, and Fig. 2 a diagrammatic sketch.
The float moves in a cast iron cylinder, having at its lower part a
large number of apertures of small diameter, so that the motion of the
waves does not perceptibly influence the level of the water in the
interior of the cylinder. It is attached to a copper ribbon, B, whose
other extremity is fixed to the drum, T. The ribbon winds around the
latter in the rising motion of the float, owing to a spiral spring
arranged so as to act upon the drum. The tension of this spring goes
on increasing in measure as the float descends.

[Illustration: FIG. 1.--FLOAT OF SIEMENS AND HALSKE'S MARIGRAPH.]

[Illustration: FIG. 2.]

This difference in tension is utilized for balancing at every instant
the weight of the ribbon unwound, and thus causing the float to
immerse itself in the water to a constant degree. The ribbon, B, is
provided throughout its length with equidistant apertures that exactly
correspond to tappets that project from the circumference of the
wheel, R. When the float moves its position, the wheel, R, begins to
turn and carries along in doing so the pinion, w, which revolves
over the toothed wheels, s1, s2, and s3. The thickness of w
is equal to that of the three wheels, s1, s2, and s3, and a
special spring secures at every instant an intimate contact between
the pinion and the said wheels. These latter are insulated from each
other and from the axle upon which they are keyed, and communicate,
each of them, with conductors, I., II., and III. They are so formed
and mounted that, in each of them, the tooth in one corresponds to the
interspace in the two others. As a result of this, in the motion of
the pinion, w, the latter is never in contact with but one of the
three wheels, s1, s2, and s3.

If we add that the lines, I., II., and III. are united at the shore
station with one of the poles of a pile whose other pole is connected
with the earth, and that w communicates with the earth through the
intermedium of R, and the body of the apparatus, it is easy to see
that in a vertical motion of the float in one direction we shall have
currents succeeding each other in the order I., II., III., I., II.,
etc., while the order will become III., II., I., III., II., etc., if
the direction of the float's motion happen to change.

[Illustration: FIG. 3.]

[Illustration: FIG. 4.]

In order to understand how a variation in currents of this kind can be
applied in general for producing a rotary motion in the two
directions, it will only be necessary to refer to Figs. 3 and 4. The
conductors, L1, L2, and L3 communicate with the bobbins of
three electromagnets, E1, E2, and E3, whose poles are bent at
right angles to the circumference of the wheel, R. There is never but
one pole opposite a tooth. The distance between two consecutive poles
must be equal to a multiple of the pitch increased (Fig. 3) or
diminished (Fig. 4) by one-third thereof. It will be seen upon a
simple inspection of the figures that R will revolve in the direction
of the hands of a watch when the currents follow the order L1,
L2, L3, etc., in the case shown in Fig. 3, while in the case
shown in Fig. 4 the rotary motion will be in the contrary direction
for this same order of currents. But, in both cases, and this is the
important point, the direction of rotation changes when the order in
the succession of currents; is inverted. Fig. 6 gives a perspective
view of the registering apparatus, and Fig. 5 represents it in
diagram. It will be at once seen that, the toothed wheel, r, is
reduced to its simplest expression, since it consists of two teeth
only. The electro-magnets are arranged at an angle of 120°, and for a
change of current the wheel, r, describes an angle of 60°, that is
to say, a sixth of a circumference. The motion of r is transmitted, by
means of the pinion, d, and the wheel, e, to the wheel, T. For a
one-meter variation in level the wheel, T, makes one complete
revolution. It is divided into 100 equal parts, and each arc therefore
corresponds to a difference of one centimeter in the level, and
carries, engraved in projection, the corresponding number. As a
consequence, there is upon the entire circumference a series of
numbers from to 99. The axle upon which the wheel, T, is keyed is
prolonged, on the side opposite e, by a threaded part, a, which
actuates a stylet, g. This latter is held above by a rod, I, which
is connected with a fork movable around a vertical axis, shown in Fig.
6. The rectilinear motion of g is 5 mm. for a variation of one meter
in level. Its total travel is consequently 40 mm. The sheet of paper
upon which the indications are taken, and which is shown of actual
size in Fig. 7, winds around the drum, P, and receives its motion from
the cylinder, W. This sheet is covered throughout its length with fine
prepared paper that permits of taking the imprints by impression.

[Illustration: FIG. 5]

[Illustration: FIG. 6--RECEIVER OF SIEMENS AND HALSKE'S MARIGRAPH.]

[Illustration: FIG. 7]

This stated, the play of the apparatus may be easily understood. Every
ten minutes a regulating clock closes the circuit of the local pile,
B2, and establishes a contact at C. The electro-magnet, E4,
attracts its armature, and thus acts upon the lever, h, which
presses the sheet of paper against the stylet in front that serves to
mark the level of the lowest waters, and against the stylet, g, and
the wheels, T and Z. In falling back, the lever, h, causes the
advance, by one notch, of the ratchet wheel that is mounted at the
extremity of the cylinder W, and thus displaces the sheet of paper a
distance of 5 mm. The wheel, Z, carries engraved in projection upon
its circumference the hours in Roman figures, and moves forward one
division every 60 minutes. The motion of this wheel is likewise
controlled by the cylinder, W.

It will be seen upon referring to Fig. 7, that there is obtained a
very sharp curve marked by points. We have a general view on
considering the curve itself, and the height in meters is read
directly. The fractions of a meter, as well as the times, are in the
margin. Thus, at the point, a, the apparatus gives at 3 o'clock and
20 minutes a height of tide of 4.28 m. above the level of the lowest
water.

This apparatus might possibly operate well, and yet not be in accord
with the real indications of the float, so it has been judged
necessary to add to it the following control.

Every time the float reaches 3 meters above the level of the lowest
tide, the circuit of one of the lines that is open at this moment
(that of line I, for example) closes at C (Fig. 2), into this new
circuit there is interposed a considerable resistance, W, so that the
energy of the current is weakened to such a point that it in nowise
influences the normal travel of the wheel, r. At the shore station,
there is placed in deviation a galvanoscope, K, whose needle is
deflected. It suffices, then, to take datum points upon the
registering apparatus, upon the wheel, T, and the screw, a, in such
a way as to ascertain the moment at which the stylet, g, is going to
mark 3 meters. At this moment the circuit of the galvanoscope, K, is
closed, and we ascertain whether there is a deviation of the needle.

As the sea generally rises to the height of 3 meters twice a day, it
is possible to control the apparatus twice a day, and this is fully
sufficient.

It always belongs to practice to judge of an invention. Mr. Von
Hefner-Alteneck tells us that two of these apparatus have been set
up--one of them a year ago in the port of Kiel, and the other more
recently at the Isle of Wangeroog in the North Sea--and that both have
behaved excellently since the very first day of their installation. We
shall add nothing to this, since it is evidently the best eulogium
that can be accorded them.--_La Lumiere Electrique._

       *       *       *       *       *




DELUNE & CO.'S SYSTEM OF LAYING UNDERGROUND CABLES.


In recent times considerable attention has been paid to the subject of
laying telegraph cables underground, and various methods have been
devised. In some cases the cables have been covered with an armor of
iron, and in others they have been inclosed in cast-iron pipes. For
telephonic service they are generally inclosed in leaden tubes. What
this external envelope shall be that is to protect the wires from
injury is a question of the highest importance, since not only the
subject of protection is concerned, but also that of cost. It is
therefore interesting to note the efforts that are being made in this
line of electric industry.

[Illustration: FIG. 1. Section of the Pipe Open.]

[Illustration: FIG. 2. Section of the Pipe Closed.]

Messrs. Delune & Co. have recently taken out a patent for an
arrangement consisting of pipes made of beton. The annexed cuts,
borrowed from _L'Electricite_, represent this new system. The pipes,
which are provided with a longitudinal opening, are placed end to end
and coupled with a cement sleeve. The cables are put in place by
simply unwinding them as the work proceeds, and thus all that traction
is done away with that they are submitted to when cast iron pipes are
used. When once the cables are in place the longitudinal opening is
stopped up with cement mortar, and in this way a very tight conduit is
obtained whose hardness increases with time. The value of the system
therefore depends, as in all cement work, on the care with which the
manufacturing is done.

Experiments have been made with the system at Toulouse, by the
Minister of Post Offices and Telegraphs, and at Lyons, by the General
Society of Telephones. Here, as with all similar questions, no opinion
can be pronounced until after a prolonged experience. But we cannot
help setting forth the advantages that the system offers. These are,
in the first place, a saving of about 50 per cent. over iron pipe, and
in the second, a better insulation, and consequently a better
protection of the currents against all kinds of disturbance, since a
non-conducting mass of cement is here substituted for metal.

       *       *       *       *       *




ELECTRICITY APPLIED TO HORSE-SHOEING.


"There is nothing new but what has been forgotten," said Marie
Antoinette to her milliner, Mdlle. Bertin, and what is true of fashion
is also somewhat so of science. Shoeing restive horses by the aid of
electricity is not new, experiments thereon having been performed as
long ago as 1879 by Mr. Defoy, who operated with a small magneto
machine.

But the two photographs reproduced in Figs. 1 and 2 have appeared to
us curious enough to be submitted to our readers, as illustrating Mr.
Defoy's method of operating with an unruly animal.

[Illustration: FIG. 1.--THE HORSE RECEIVING THE CURRENT.]

The battery used was a small Grenet bichromate of potash pile, which
was easy to graduate on account of the depth to which the zinc could
be immersed. This pile was connected with the inductor of a small
Ruhmkorff coil, whose armature was connected with a snaffle-bit placed
in the horse's mouth.

[Illustration: FIG. 2.--THE HORSE CONQUERED.]

This bit was arranged as follows (Fig. 3): The two conductors, which
were uncovered for a length of about three centimeters at their
extremity, were placed opposite each other on the two joints of the
snaffle, and about five or six centimeters apart. The mouth-pieces of
the bit had previously been inclosed in a piece of rubber tubing, in
order to insulate the extremities of the conductors and permit the
recomposition of the current to take place through the animal's tongue
or palate.

Each of the bare ends of the conductors was provided, under a circular
brass ligature, with a small damp sponge, which, surrounding the
mouth-piece, secured a perfect contact of each end of the circuit with
the horse's mouth.

[Illustration: FIG. 3.--ARRANGEMENT OF THE BIT]

The horse having been led in, defended himself vigorously as long as
an endeavor was made to remove his shoes by the ordinary method, but
the current had acted scarcely fifteen seconds when it became possible
to lift his feet and strike his shoes with the hammer.

The experimenter having taken care during this experiment to place the
bobbin quite near the horse's ear, so that he could hear the humming
of the interrupter, undertook a second experiment in the following
way: Having detached the conductors from the armature, he placed
himself in front of the horse (as shown in Fig. 2), and began to
imitate the humming sound of the interrupter with his mouth. The
animal at once assumed the stupefied position that the action of the
current gave him in the first experiment, and allowed his feet to be
lifted and shod without his even being held by the snaffle.

The horse was for ever after subdued, and yet his viciousness and his
repugnance to shoeing were such that he could only be shod previously
by confining his legs with a kicking-strap.

It should be noted that the action of the induction coil, mounted as
this was, was very feeble and not very painful; and yet it was very
disagreeable in the mouth, and gave in this case a shock with a
sensation of light before the eyes, as we have found by experimenting
upon ourselves.

From our own most recent experiments, we have ascertained the
following facts, which may guide every horse-owner in the application
of electricity to an animal that is opposed to being shod: (1) To a
horse that defends himself because he is irritable by temperament, and
nervous and impressionable (as happens with animals of pure or nearly
pure blood), the shock must be administered feebly and gradually
before an endeavor is made to take hold of his leg. The horse will
then make a jump, and try to roll over. The jump must be followed,
while an assistant holds the bridle, and the action of the current
must be at once arrested. After this the horse will not endeavor to
defend himself, and his leg may be easily handled.

(2) Certain large, heavy, naturally ugly horses kick through sheer
viciousness. In this case, while the current is being given it should
be gradually increased in intensity, and the horse's foot must be
seized during its action. In most cases the passage of a current
through such horses (whose mucous membrane is less sensitive) produces
only a slightly stupefied and contracted position of the head,
accompanied with a slight tremor. The current must be shut off as soon
as the horse's foot is well in one's hand, and be at once renewed if
he endeavors to defend himself again, as is rarely the case. It is a
mare of this nature that is represented in the annexed figures.

We know that this same system has been applied for bringing to an
abrupt standstill runaway horses, harnessed to vehicles; but knowing
the effect of a sudden stoppage under such circumstances, we believe
that the remedy would prove worse than the disease, since the coachman
and vehicle, in obedience to the laws of inertia, would continue their
motion and pass over the animals, much to their detriment.--_Science
et Nature._

       *       *       *       *       *




ESTEVE'S AUTOMATIC PILE.


Mr. Esteve has recently devised a generator of electricity which he
claims to be energetic, constant, and always ready to operate. The
apparatus is designed for the production of light and for actuating
electric motors, large induction bobbins, etc.

We give a description of it herewith from data communicated by its
inventor.

The accompanying cut represents a battery of 6 elements, with a
reservoir, R, for the liquid, provided at its lower part with a cock
for allowing the liquid to enter the pile. The vessels of the
different elements are of rectangular form. At the upper part, and in
the wider surfaces of each, there are two tubes. The first tube of the
first vessel receives the extremity of a safety-tube, A, whose other
extremity enters the upper part of the reservoir, R. This tube is
designed for regulating the flow of the liquid into the pile. When the
cock, r, is too widely open, the liquid might have a tendency to
flow over the edges of the vessel; but this would close the orifice of
the tube, A, and, as the air would then no longer enter the reservoir,
R, the flow would be stopped automatically. The second tube of the
first vessel is connected with a lead tube, 1, one of the extremities
of which enters the second vessel. The other tubes are arranged in the
same way in the other vessels. The renewal of the liquids is effected
by displacement, in flowing upward from one element over into another;
and the liquids make their exit from the pile at D, after having
served six times. The electrodes of the two first elements are
represented as renewed in the cut, in order to show the arrangement of
the tubes.

[Illustration: ESTEVE'S AUTOMATIC PILE.]

_Dimensions._--The zinc, 2, has a superficies of 15×20 centimeters,
and is cut out of the ordinary commercial sheet metal. It may be
turned upside down when one end has become worn away, thus permitting
of its being entirely utilized. The negative electrode is formed of
four carbons, which have, each of them, a superficies of 8×21
centimeters. These four carbons are less fragile and are more easily
handled than two having the same surface. Their arrangement is shown
at the left of the figure. They are fixed to a strip of copper, a,
to which is soldered another strip, L, bent at right angles. There are
thus two pairs of carbon per element, and these are simply suspended
from a piece of wood, as shown in the figure. Upon this wooden holder
will be seen the two strips, LL, that are designed to be put in
contact with the zinc of the succeeding element by means of pinchers
that connect the electrodes with one another. This arrangement permits
the pile to be taken apart very quickly.

_Charging, Work, and Duration of the Pile._--The inventor has made a
large number of experiments with solutions of bichromate of potash of
various degrees of saturation, and has found the following to give the
best results:


     Bichromate of potash.           1 kilogramme.
     Sulphuric acid                  2 liters.
     Water                           8    "


When a larger quantity of the salt is used, crystallization occurs in
the pile.

                          Constants and work    Constants and work
                          of an element         of a round Bunsen
                          having a zinc of      element, 20×30 cm.
                          16×20 cm.

  Volts.                       1.9                   1.8
  Resistance.                  0.05                  0.24
  Work disposable in the
  external circuit.           1.839 k.              0.344 k.


The work disposable in the external circuit is deduced from the
formula:

                 T = E²/(4R × 9.81)

It will be seen that an element thus charged gives as much energy as
5.3 large Bunsen elements.

The battery is charged with 10 liters of solution, and is capable of
furnishing for 5 hours a current of 7 amperes with a difference of
potential of 9 volts at the pile terminals. The work, according to the
formula (EI)/g, equals 6.422 kilogram-meters; with a feebler
resistance in the external circuit it is capable of producing a
current of 19 amperes for an hour and an half. In this case the
resistance of the external circuit equals the interior resistance of
the pile. Upon immersing the electrodes in new liquid, and with no
resistance in the external circuit, the current may reach 100 amperes.
On renewing the liquids during the operation of the pile, a current of
7 amperes is kept up if about a liter of saturation per hour be
allowed to pass into the battery. For five hours, then, only 5 liters
are used instead of the 10 that are necessary when the liquid is not
renewed while the pile is in action.--_La Nature._

       *       *       *       *       *




WOODWARD'S DIFFUSION MOTOR.


The energy produced by the phenomena of diffusion is exhibited in
lecture courses by placing a bell glass filled with hydrogen over a
porous vessel at whose base is fixed a glass tube that dips into
water. The hydrogen, in diffusing, enters the porous vessel, increases
the internal pressure, and a number of bubbles escapes from the tube.
On withdrawing the bell glass of hydrogen, the latter becomes diffused
externally, a lower pressure occurs in the porous vessel, and the
level of the water rises.

The arrangement devised by Mr. C.J. Woodward, and recently presented
to the Physical Society of London, is an adaptation of this experiment
to the production of an oscillating motion by alternations in the
internal and external diffusion of the hydrogen.

The apparatus, represented herewith, consists of a scale beam about
three feet in length that supports at one end a scale pan and weights,
and, at the other, a corked porous vessel that carries a glass tube,
c, which dips into a vessel containing either water or methylic
alcohol. Three or four gas jets, one of which is shown at E, are
arranged around the porous vessel, as close as possible, but in such a
way as not to touch it during the oscillation of the beam. These gas
jets communicate with a gasometer tilled with hydrogen, the bell of
which is so charged as to furnish a jet of sufficient strength.
Experience will indicate the best place to give the gas jets, but, in
general, it is well to locate them at near the center of the porous
vessel when the beam is horizontal.

[Illustration]

It is now easy to see how the device operates. When the hydrogen comes
in presence of the porous vessel it becomes diffused therein, and the
pressure exerted in the interior then produces an ascent. When the
bottom of the porous vessel gets above the jets, the internal
diffusion ceases and the hydrogen becomes diffused externally, the
internal pressure diminishes, and the vessel descends. The vessel then
comes opposite the jets of hydrogen and the same motion occurs again,
and soon indefinitely. The work produced by this motor, which has
purely a scientific interest, is very feeble, and much below that
assigned to it by theory. In order to obtain a maximum, it would be
necessary to completely surround the porous vessel each time with
hydrogen, and afterward remove the jets to facilitate the access of
air. All the mechanical arrangements employed for obtaining such a
result have failed, because the friction introduced by the maneuvering
parts also introduces a resistance greater than the motor can
overcome. There is therefore a waste of energy due to the continuous
flow of hydrogen; but the apparatus, for all that, constitutes none
the less an original and interesting device.--_La Nature._

       *       *       *       *       *




SOME RELATIONS OF HEAT TO VOLTAIC AND THERMO-ELECTRIC ACTION OF METALS
IN ELECTROLYTES.[1]

   [Footnote 1: Read before the Royal Society, Nov., 1883.]

By G. GORE, F.R.S., LL.D.


The experiments described in this paper throw considerable light upon
the real cause of the voltaic current. The results of them are
contained in twenty tables; and by comparing them with each other, and
also by means of additional experiments, the following general
conclusions and chief facts were obtained.

When metals in liquids are heated, they are more frequently rendered
positive than negative in the proportion of about 2.8 to 1.0; and
while the proportion in weak solutions was about 2.29 to 1.0, in
strong ones it was about 3.27 to 1.0, and this accords with their
thermo-electric behavior as metals alone. The thermo-electric order of
metals in liquids was, with nearly every solution, whether strong or
weak, widely different from the thermo-electric order of the same
metals alone. A conclusion previously arrived at was also confirmed,
viz., that the liquids in which the hot metal was thermo-electro-positive
in the largest proportion of cases were those containing highly
electro-positive bases, such as the alkali metals. The thermo-electric
effect of _gradually_ heating a metal in a liquid was sometimes
different from that of _suddenly_ heating it, and was occasionally
attended by a reversal of the current.

Degree of strength of liquid greatly affected the thermo-electric
order of metals. Increase of strength usually and considerably
increased the potential of metals thermo-electro-negative in liquids,
and somewhat increased that of those positive in liquids.

The electric potential of metals, thermo-electro-positive in weak
liquids, was usually about 3.87 times, and in strong ones 1.87 times,
as great as of those which were negative. The potential of the
strongest thermo-electric couple, viz., that of aluminum in weak
solution of sodic phosphate, was 0.66 volt for 100° F. difference of
temperature, or about 100 times that of a bismuth and antimony couple.

Heating one of the metals, either the positive or negative, of a
voltaic couple, usually increased their electric difference, making
most metals more positive, and some more negative; while heating the
second one also usually neutralized to a large extent the effect of
heating the first one. The electrical effect of heating a voltaic
couple is nearly wholly composed of the united effects of heating each
of the two metals separately, but is not however exactly the same,
because while in the former case the metals are dissimilar, and are
heated to the same temperature, in the latter they are similar, but
heated to different temperatures. Also, when heating a voltaic pair,
the heat is applied to two metals, both of which are previously
electro-polar by contact with each other as well as by contact with
the liquid; but when heating one junction of a metal and liquid
couple, the metal has not been previously rendered electro-polar by
contact with a different one, and is therefore in a somewhat different
state. When a voltaic combination, in which the positive metal is
thermo-negative, and the negative one is thermo-positive, is heated,
the electric potential of the couple diminishes, notwithstanding that
the internal resistance is decreased.

Magnesium in particular, also zinc and cadmium, were greatly depressed
in electromotive force in electrolytes by elevation of temperature.
Reversals of position of two metals of a voltaic couple in the tension
series by rise of temperature were chiefly due to one of the two
metals increasing in electromotive force faster than the other, and in
many cases to one metal increasing and the other decreasing in
electromotive force, but only in a few cases was it a result of
simultaneous but unequal diminution of potential of the two metals.
With eighteen different voltaic couples, by rise of temperature from
60° to 160° F., the electromotive force in twelve cases was increased,
and in six decreased, and the average proportions of increase for the
eighteen instances was 0.10 volt for the 100° F. of elevation.

A great difference in chemical composition of the liquid was attended
by a considerable change in the order of the volta-tension series, and
the differences of such order in two similar liquids, such as
solutions of hydric chloride and potassic chloride, were much greater
than those produced in either of those liquids by a difference of 100°
F. of temperature. Difference of strength of solution, like difference
of composition or of temperature, altered the order of such series
with nearly every liquid; and the amount of such alteration by an
increase of four or five times in the strength of the liquid was
rather less than that caused by a difference of 100° F. of
temperature. While also a variation of strength of liquid caused only
a moderate amount of change of order in the volta-tension series, it
produced more than three times that amount of change in the
thermo-electric tension series. The usual effect of increasing the
strength of the liquid upon the volta-electromotive force was to
considerably increase it, but its effect upon the thermo-electro-motive
force was to largely decrease it. The degree of potential of a metal
and liquid thermo-couple was not always exactly the same at the same
temperature during a rise as during a fall of temperature; this is
analogous to the variations of melting and solidifying points of
bodies under such conditions, and also to that of supersaturation of a
liquid by a salt, and is probably due to some hinderance to change of
molecular movement.

The rate of ordinary chemical corrosion of each metal varied in every
different liquid; in each solution also it differed with every
different metal. The most chemically positive metals were usually the
most quickly corroded, and the corrosion of each metal was usually the
fastest with the most acid solutions. The rate of corrosion at any
given temperature was dependent both upon the nature of the metal and
upon that of the liquid, and was limited by the most feebly active of
the two, usually the electrolyte. The order of rate of corrosion of
metals also differed in every different liquid. The more dissimilar
the chemical characters of two liquids, the more diverse usually was
the order of rapidity of corrosion of a series of metals in them. The
order of rate of simple corrosion in any of the liquids examined
differed from that of chemico-electric and still more from that of
thermo-electric tension. Corrosion is not the cause of thermo-electric
action of metals in liquids.

Out of fifty-eight cases of rise of temperature the rate of ordinary
corrosion was increased in every instance except one, and that was
only a feeble exception--the increase of corrosion from 60° to 160° F.
with different metals was extremely variable, and was from 1.5 to 321.6
times. Whether a metal increased or decreased in thermo-electromotive
force by being heated, it increased in rapidity of corrosion. The
proportions in which the most corroded metal was also the most
thermo-electro-positive one was 65.57 per cent. in liquids at 60° F.,
and 69.12 in the same liquids at 160° F.; and the proportion in which
it was the most chemico-electro-positive at 60 F. was 84.44 per cent,
and at 160° F. 80.77 per cent. The proportion of cases therefore in
which the most chemico-electro-negative metal was the most corroded
one increased from 15.56 to 19.23 per cent, by a rise of temperature
of 100° F. Comparison of these proportions shows that corrosion
usually influenced in a greater degree chemico-electric rather than
thermo-electric actions of metals in liquids. Not only was the
relative number of cases in which the volta-negative metal was the
most corroded increased by rise of temperature, but also the average
relative loss by corrosion of the negative to that of the positive one
was increased from 3.11 to 6.32.

The explanation most consistent with all the various results and
conclusions is a kinetic one: That metals and electrolytes are
throughout their masses in a state of molecular vibration. That the
molecules of those substances, being frictionless bodies in a
frictionless medium, and their motion not being dissipated by
conduction or radiation, continue incessantly in motion until some
cause arises to prevent them. That each metal (or electrolyte), when
unequally heated, has to a certain extent an unlike class of motions
in its differently heated parts, and behaves in those parts somewhat
like two metals (or electrolytes), and those unlike motions are
enabled, through the intermediate conducting portion of the substance,
to render those parts electro-polar. That every different metal and
electrolyte has a different class of motions, and in consequence of
this, they also, by contact alone with each other at the same
temperature, become electro-polar. The molecular motion of each
different substance also increases at a different rate by rise of
temperature.

This theory is equally in agreement with the chemico-electric results.
In accordance with it, when in the case of a metal and an electrolyte,
the two classes of motions are sufficiently unlike, chemical corrosion
of the metal by the liquid takes place, and the voltaic current
originated by inherent molecular motion, under the condition of
contact, is maintained by the portions of motion lost by the metal and
liquid during the act of uniting together. Corrosion therefore is an
effect of molecular motion, and is one of the modes by which that
motion is converted into and produces electric current.

In accordance with this theory, if we take a thermo-electric pair
consisting of a non-corrodible metal and an electrolyte (the two being
already electro-polar by mutual contact), and heat one of their points
of contact, the molecular motions of the heated end of each substance
at the junction are altered; and as thermo-electric energy in such
combinations usually increases by rise of temperature, the metal and
liquid, each singly, usually becomes more electro polar. In such a
case the unequally heated metal behaves to some extent like two
metals, and the unequally heated liquid like two liquids, and so the
thermo-electric pair is like a feeble chemico-electric one of two
metals in two liquids, but without corrosion of either metal. If the
metal and liquid are each, when alone, thermo-electro-positive, and if,
when in contact, the metal increases in positive condition faster than
the liquid by being heated, the latter appears thermo-electro-negative,
but if less rapidly than the liquid, the metal appears
thermo-electro-negative.

As also the proportion of cases is small in which metals that are
positive in the ordinary thermo-electric series of metals only become
negative in the metal and liquid ones (viz., only 73 out of 286 in
weak solutions, and 48 out of the same number in strong ones), we may
conclude that the metals, more frequently than the liquids, have the
greatest thermo-electric influence, and also that the relative
largeness of the number of instances of thermo-electro-positive metals
in the series of metals and liquids, as in the series of metals only,
is partly a consequence of the circumstance that rise of temperature
usually makes substances--metals in particular--electro-positive.
These statements are also consistent with the view that the elementary
substances lose a portion of their molecular activity when they unite
to form acids or salts, and that electrolytes therefore have usually a
less degree of molecular motion than the metals of which they are
partly composed.

The current from a thermo-couple of metal and liquid, therefore, may
be viewed as the united result of difference of molecular motion,
first, of the two junctions, and second, of the two heated (or cooled)
substances; and in all cases, both of thermo- and chemico-electric
action, the immediate true cause of the current is the original
molecular vibrations of the substances, while contact is only a static
permitting condition. Also that while in the case of thermo-electric
action the sustaining cause is molecular motion, supplied by an
external source of heat, in the case of chemico-electric action it is
the motion lost by the metal and liquid when chemically uniting
together. The direction of the current in thermo-electric cases
appears to depend upon which of the two substances composing a
junction increases in molecular activity the fastest by rise of
temperature, or decreases the most rapidly by cooling.

       *       *       *       *       *




AIR REFRIGERATING MACHINE.


[Illustration: IMPROVED AIR REFRIGERATING MACHINE.]

Messrs. J. & E. Hall, Dartford, exhibit at the International Health
Exhibition, London, in connection with a cold storage room, two sizes
of Ellis' patent air refrigerator, the larger one capable of
delivering 5,000 cubic feet of cold air per hour, when running at a
speed of 150 revolutions per minute; and the smaller one 2,000 cubic
feet of cold air per hour, at 225 revolutions per minute. The special
features in these machines are the arrangement of parts, by which
great compactness is secured, and the adoption of flat slides for the
compressor, instead of the ordinary beat valves, which permits of a
high rate of revolution without the objectionable noise which is
caused by clacks beating on their seats. The engraving shows the
general arrangement of the apparatus. Figs. 1 to 4 show details of the
compression and expansion valves, which are ordinary flat slides,
partly balanced, and held up to their faces by strong springs from
behind. The steam, compression, and expansion cylinders are severally
bolted to the end of a strong frame, which though attached to the
cooler box does not form part of it, the object being to meet the
strains between the cylinders and shaft in as direct a manner as
possible without allowing them to act on the cooler casting. Each
cylinder is double acting, the pistons being coupled to the shaft by
three connecting rods, the two outer ones working upon crank pins
fixed to overhung disks, and the center one on a crank formed in the
shaft. The slide valves for all the cylinders are driven from two
weigh shafts, the main valve shaft being actuated by a follow crank,
and the expansion and cut off valves from the crosshead pin of the
compressor. The machines may be used either in the vertical position
as exhibited, or may be fixed horizontally; and it is stated that the
construction is such as to admit of speeds of 200 and 300 revolutions
per minute respectively for the larger and smaller machines, under
which conditions the delivery of cold air may be taken at about 7,000
and 2,600 cubic feet per hour. Messrs. Hall also make this class of
refrigerator without the steam cylinder, and arranged to be driven by
a belt from a gas engine or any existing motive power.

       *       *       *       *       *




A GAS RADIATOR AND HEATER.


[Illustration: Fig. 1 & Fig. 2 A GAS RADIATOR AND HEATER.]

There is now being introduced into Germany a gas radiator and heater,
the invention of Herr Wobbe. It consists, as will be seen in engraving
above, of a series of vertical U-shaped pipes, of wrought iron, 50
millimeters (2 inches) in diameter. The two legs of the U are of
unequal length; the longer being about 5 feet, and the shorter 3 feet
(exclusive of the bend at the top). Beneath the open end of the
shorter leg of each pipe is placed a burner, attached to a horizontal
gas-pipe, which turns upon an axis. The object of having this pipe
rotate is to bring the burners into an inclined position--shown by the
dotted lines in Fig. 2--for lighting them. On turning them back to the
vertical position, the heated products of combustion pass up the
shorter tube and down the longer, where they enter a common
receptacle, from which they pass into the chimney or out of doors.
Surrounding the pipes are plates of sheet iron, inclined at the angle
shown in Fig. 2. The object of the plates is to prevent the heated air
of the room from passing up to the ceiling, and send it out into the
room. To prevent any of the pipes acting as chimneys, and bringing the
products of combustion back into the room, as well as to avoid any
back-pressure, a damper is attached to the outlet receptacle. The
heated gas becomes cooled so much (to about 100° Fahr.) that water is
condensed and precipitated, and collects in the vessel below the
outlet. Each burner has a separate cock, by which it may be kept
closed, half-open, or open. To obviate danger of explosion, there is a
strip of sheet iron in front of the burners, which prevents their
being lighted when in a vertical position; so that, in case any
unburned gas gets into the pipes, it cannot be ignited, for the
burners can only be lighted when inclined to the front. In starting
the stove the burners are lighted, in the inclined position; the chain
from the damper pulled up; the burners set vertical; and, as soon as
they are all drawing well into the tubes, the damper is closed. If
less heat is desired, the cocks are turned half off. It is not
permissible to entirely extinguish some of the burners, unless the
unused pipes are closed to prevent the products of combustion coming
back into the room. The consumption of gas per burner, full open, with
a pressure of 8/10, is said to be only 4-3/8 cubic feet per hour.

       *       *       *       *       *




CONCRETE WATER PIPES.


Concrete water pipes of small diameter, according to a foreign
contemporary, are used in parts of France, notably for water mains for
the towns of Coulommiers and Aix-en-Provence. The pipes were formed of
concrete in the trench itself. The mould into which the concrete was
stamped was sheet iron about two yards in length. The several pipes
were not specially joined to each other, the joints being set with
mortar. The concrete consisted of three parts of slow setting cement
and three parts of river sand, mixed with five parts of limestone
debris. The inner diameter of the pipes was nine inches; their
thickness, three inches. The average fall is given at one in five
hundred; the lowest speed of the current at one foot nine inches per
second. To facilitate the cleaning of the pipes, man-holes are
constructed every one hundred yards or so, the sides of which are also
made of concrete. The trenches are about five feet deep. The work was
done by four men, who laid down nearly two hundred feet of pipe in a
working day; the cost was about ninety-three cents per running yard.
It is claimed as an advantage for the new method that the pipes adhere
closely to the inequalities of the trench, and thus lie firmly on the
ground. When submitted to great pressure, however, they have not
proved effective, and the method, consequently, is only suitable for
pipes in which there is no pressure, or only a very trifling one.

       *       *       *       *       *




THE SELLERS STANDARD SYSTEM OF SCREW THREADS, NUTS, AND BOLT HEADS.


   _____________________________________________________
  |                                                     |
  |                  SCREW THREADS.                     |
  |_____________________________________________________|
  |        |        |                 |         |       |
  | Diam.  |Threads |    Diameter     | Area of | Width |
  |  of    |  per   |   at root of    | Bolt at |  of   |
  | Screw. | inch.  |     Thread.     | root of | Flat. |
  |        |        |                 | Thread. |       |
  |________|________|_________________|_________|_______|
  |        |        |       |         |         |       |
  |   1/4  | 20     |  .185 |   13/64 |    .026 | .0062 |
  |   5/16 | 18     |  .240 |   15/64 |    .045 | .0074 |
  |   3/8  | 16     |  .294 |   19/64 |    .067 | .0078 |
  |   7/16 | 14     |  .344 |   11/32 |    .092 | .0089 |
  |   1/2  | 13     |  .400 |   13/32 |    .125 | .0096 |
  |   9/16 | 12     |  .454 |   29/64 |    .161 | .0104 |
  |   5/8  | 11     |  .507 |   33/64 |    .201 | .0113 |
  |   3/4  | 10     |  .620 |    5/8  |    .301 | .0125 |
  |   7/8  |  9     |  .731 |   47/64 |    .419 | .0138 |
  |        |        |       |         |         |       |
  | 1      |  8     |  .837 |   27/32 |    .550 | .0156 |
  | 1-1/8  |  7     |  .940 |   15/16 |    .693 | .0178 |
  | 1-1/4  |  7     | 1.065 | 1- 1/16 |    .890 | .0178 |
  | 1-3/8  |  6     | 1.160 | 1- 5/32 |   1.056 | .0208 |
  | 1-1/2  |  6     | 1.284 | 1- 9/32 |   1.294 | .0208 |
  | 1-5/8  |  5-1/2 | 1.389 | 1-25/64 |   1.515 | .0227 |
  | 1-3/4  |  5     | 1.491 | 1-31/64 |   1.746 | .0250 |
  | 1-7/8  |  5     | 1.616 | 1-39/64 |   2.051 | .0250 |
  |        |        |       |         |         |       |
  | 2      |  4-1/2 | 1.742 | 1-23/32 |   2.301 | .0277 |
  | 2-1/4  |  4-1/2 | 1.962 | 1-31/32 |   3.023 | .0277 |
  | 2-1/2  |  4     | 2.176 | 2-11/64 |   3.718 | .0312 |
  | 2-3/4  |  4     | 2.426 | 2-27/64 |   4.622 | .0312 |
  |        |        |       |         |         |       |
  | 3      |  3-1/2 | 2.629 | 2- 5/8  |   5.428 | .0357 |
  | 3-1/4  |  3-1/2 | 2.879 | 2- 7/8  |   6.509 | .0357 |
  | 3-1/2  |  3-1/4 | 3.100 | 3- 3/32 |   7.547 | .0384 |
  | 3-3/4  |  3     | 3.317 | 3- 5/16 |   8.614 | .0413 |
  |        |        |       |         |         |       |
  | 4      |  3     | 3.567 | 3- 9/16 |   9.993 | .0413 |
  | 4-1/4  |  2-7/8 | 3.798 | 3-51/64 |  11.329 | .0435 |
  | 4-1/2  |  2-3/4 | 4.028 | 4- 1/32 |  12.742 | .0454 |
  | 4-3/4  |  2-5/8 | 4.256 | 4- 1/4  |  14.226 | .0476 |
  |        |        |       |         |         |       |
  | 5      |  2-1/2 | 4.480 | 4-31/64 |  15.763 | .0500 |
  | 5-1/4  |  2-1/2 | 4.730 | 4-47/64 |  17.570 | .0500 |
  | 5-1/2  |  2-3/8 | 4.953 | 4-61/64 |  19.267 | .0526 |
  | 5-3/4  |  2-3/8 | 5.203 | 5-13/64 |  21.261 | .0526 |
  | 6      |  2-1/4 | 5.423 | 5-27/64 |  23.097 | .0555 |
  |________|________|_________________|_________|_______|
   _____________________________________________________________
  |                                                              |
  |                              NUTS.                           |
  |___________________ __________________________________________|
  |         |          |          |          |         |         |
  | Short   | Short    |  Long    |  Long    | Thick-  | Thick-  |
  | Diam.   | Diam.    |  Diam.   |  Diam.   |  ness   |  ness   |
  | Rough.  | Finish.  |  Rough.  |  Rough.  | Rough.  | Finish. |
  |         |          |          |          |         |         |
  | (Hex.)  | (Hex.)   |  (Hex.)  | (Square) |         |         |
  |_________|_________ |__________|__________|_________|_________|
  |         |          |          |          |         |         |
  |    1/2  |    7/16  |    37/64 |     7/10 |    1/4  |    3/16 |
  |   19/32 |   17/32  |    11/16 |    10/12 |    5/16 |    1/4  |
  |   11/16 |    5/8   |    51/64 |    63/64 |    3/8  |    5/16 |
  |   25/32 |   23/33  |     9/10 |  1- 7/64 |    7/16 |    3/8  |
  |    7/8  |   13/16  |  1       |  1-15/64 |    1/2  |    7/16 |
  |   31/32 |   29/32  |  1- 1/8  |  1-23/64 |    9/16 |    1/2  |
  |  1-1/16 |  1       |  1- 7/32 |  1- 1/2  |    5/8  |    9/16 |
  |  1-1/4  |  1-3/16  |  1- 7/16 |  1-49/64 |    3/4  |   11/16 |
  |  1-7/16 |  1-3/8   |  1-21/32 |  2- 1/32 |    7/8  |   13/16 |
  |         |          |          |          |         |         |
  |  1- 5/8 |  1-9/16  |  1- 7/8  |  2-19/64 |  1      |   15/16 |
  |  1-13/16|  1- 3/4  |  2- 5/32 |  2- 9/16 |  1-1/8  | 1- 1/16 |
  |  2      |  1-15/16 |  2- 5/16 |  2-53/64 |  1-1/4  | 1- 3/16 |
  |  2- 3/16|  2- 1/8  |  2-17/32 |  3- 3/32 |  1-3/8  | 1- 5/16 |
  |  2- 3/8 |  2- 5/16 |  2- 3/4  |  3-23/64 |  1-1/2  | 1- 7/16 |
  |  2- 9/16|  2- 1/2  |  2-31/32 |  3- 5/8  |  1-5/8  | 1- 9/16 |
  |  2- 3/4 |  2-11/16 |  3- 3/16 |  3-57/64 |  1-3/4  | 1-11/16 |
  |  2-15/16|  2- 7/8  |  3-13/32 |  4- 5/32 |  1-7/8  | 1-13/16 |
  |         |          |          |          |         |         |
  |  3-1/8  |  3- 1/16 |  3- 5/8  |  4-27/64 |  2      | 1-15/16 |
  |  3-1/2  |  3- 7/16 |  4- 1/16 |  4-61/64 |  2-1/4  | 2- 3/16 |
  |  3-7/8  |  3-13/16 |  4- 1/2  |  5-31/64 |  2-1/2  | 2- 7/16 |
  |  4-1/4  |  4- 3/16 |  4-29/32 |  6       |  2-3/4  | 2-11/16 |
  |         |          |          |          |         |         |
  |  4-5/8  |  4- 9/16 |  5- 3/8  |  6-17/32 |  3      | 2-15/16 |
  |  5      |  4-15/16 |  5-13/16 |  7- 1/16 |  3-1/4  | 3- 3/16 |
  |  5-3/8  |  5- 5/16 |  6- 7/32 |  7-39/64 |  3-1/2  | 3- 7/16 |
  |  5-3/4  |  5-11/16 |  6-21/32 |  8- 1/8  |  3-3/4  | 3-11/16 |
  |         |          |          |          |         |         |
  |  6-1/8  |  6- 1/16 |  7- 3/32 |  8-41/64 |  4      | 3-15/16 |
  |  6-1/2  |  6- 7/16 |  7- 9/16 |  9- 3/16 |  4-1/4  | 4- 3/16 |
  |  6-7/8  |  6-13/16 |  7-31/32 |  9- 3/4  |  4-1/2  | 4- 7/16 |
  |  7-1/4  |  7- 3/16 |  8-13/32 | 10- 1/4  |  4-3/4  | 4-11/16 |
  |         |          |          |          |         |         |
  |  7-5/8  |  7- 9/16 |  8-27/32 | 10-49/64 |  5      | 4-15/16 |
  |  8      |  7-15/16 |  9- 9/32 | 11-23/64 |  5-1/4  | 5- 3/16 |
  |  8-3/8  |  8- 5/16 |  9-23/32 | 11- 7/8  |  5-1/2  | 5- 7/16 |
  |  8-3/4  |  8-11/16 | 10- 5/32 | 12- 3/8  |  5-3/4  | 5-11/16 |
  |  9-1/8  |  9- 1/16 | 10-19/32 | 12-15/16 |  6      | 5-15/16 |
  |_________|__________|__________|__________|_________|_________|
   _____________________________________________________________
  |                                                             |
  |                          BOLT HEADS.                        |
  |_____________________________________________________________|
  |         |         |          |          |         |         |
  | Short   | Short   |  Long    |  Long    | Thick-  | Thick-  |
  | Diam.   | Diam.   |  Diam.   |  Diam.   |  ness   |  ness   |
  | Rough.  | Finish. |  Rough.  |  Rough.  | Rough.  | Finish. |
  |         |         |          |          |         |         |
  | (Hex.)  | (Hex.)  |  (Hex.)  | (Square) |         |         |
  |_________|_________|__________|__________|_________|_________|
  |         |         |          |          |         |         |
  |    1/2  |    7/16 |    37/64 |     7/10 |    1/4  |    3/16 |
  |   19/32 |   17/32 |    11/16 |    10/12 |   19/64 |    1/4  |
  |   11/16 |    5/8  |    51/64 |    63/64 |   11/32 |    5/16 |
  |   25/32 |   23/32 |     9/16 |   1-7/64 |   25/64 |    3/8  |
  |    7/8  |   13/16 |  1       |  1-15/64 |    7/16 |    7/16 |
  |   31/32 |   29/32 |  1- 1/8  |  1-23/64 |   31/64 |    1/2  |
  | 1- 1/16 | 1       |  1- 7/32 |  1- 1/2  |   17/32 |    9/16 |
  | 1- 1/4  | 1- 3/16 |  1- 7/16 |  1-49/64 |    5/8  |   11/16 |
  | 1- 7/16 | 1- 3/8  |  1-21/32 |  2- 1/32 |   23/32 |   13/16 |
  |         |         |          |          |         |         |
  | 1- 5/8  | 1- 9/16 |  1- 7/8  |  2-19/64 |   13/16 |   15/16 |
  | 1-13/16 | 1- 3/4  |  2- 5/32 |  2- 7/16 |   29/32 | 1- 1/16 |
  | 2       | 1-15/16 |  2- 5/16 |  2-53/64 | 1       | 1- 3/16 |
  | 2- 3/16 | 2- 1/8  |  2-17/32 |  3- 3/32 | 1- 3/32 | 1- 5/16 |
  | 2- 3/8  | 2- 5/16 |  2- 3/4  |  3-23/64 | 1- 3/16 | 1- 7/16 |
  | 2- 9/16 | 2- 1/2  |  2-31/32 |  3- 5/8  | 1- 9/32 | 1- 9/16 |
  | 2- 3/4  | 2-11/16 |  3- 3/16 |  3-57/64 | 1- 3/8  | 1-11/16 |
  | 2-15/16 | 2- 7/8  |  3-13/32 |  4- 5/32 | 1-15/32 | 1-13/16 |
  |         |         |          |          |         |         |
  | 3- 1/8  | 3- 1/16 |  3- 5/8  |  4-27/64 | 1- 9/16 | 1-15/16 |
  | 3- 1/2  | 3- 7/16 |  4- 1/16 |  4-61/64 | 1- 3/4  | 2- 3/16 |
  | 3- 7/8  | 3-13/16 |  4- 1/2  |  5-31/64 | 1-15/16 | 2- 7/16 |
  | 4- 1/4  | 4- 3/16 |  4-29/32 |  6       | 2- 1/8  | 2-11/16 |
  |         |         |          |          |         |         |
  | 4- 5/8  | 4- 9/16 |  5- 3/8  |  6-17/32 | 2- 5/16 | 2-15/16 |
  | 5       | 4-15/16 |  5-13/16 |  7- 1/16 | 2- 1/2  | 3- 3/16 |
  | 5- 3/8  | 5- 5/16 |  6- 7/32 |  7-39/64 | 2-11/16 | 3- 7/16 |
  | 5- 3/4  | 5-11/16 |  6-21/32 |  8- 1/8  | 2- 7/8  | 3-11/16 |
  |         |         |          |          |         |         |
  | 6- 1/8  | 6- 1/16 |  7- 3/32 |  8-41/64 | 3- 1/16 | 3-15/16 |
  | 6- 1/2  | 6- 7/16 |  7- 9/16 |  9- 3/16 | 3- 1/4  | 4- 3/16 |
  | 6- 7/8  | 6-13/16 |  7-31/32 |  9- 3/4  | 3- 7/16 | 4- 7/16 |
  | 7- 1/4  | 7- 3/16 |  8-13/32 | 10- 1/4  | 3- 5/8  | 4-11/16 |
  |         |         |          |          |         |         |
  | 7- 5/8  | 7- 9/16 |  8-27/32 | 10-49/64 | 3-13/16 | 4-15/16 |
  | 8       | 7-15/16 |  9- 9/32 | 11-23/64 | 4       | 5- 3/16 |
  | 8- 3/8  | 8- 5/16 |  9-23/32 | 11- 7/8  | 4- 3/16 | 5- 7/16 |
  | 8- 3/4  | 8-11/16 | 10- 5/32 | 12- 3/8  | 4- 3/8  | 5-11/16 |
  | 9- 1/8  | 9- 1/16 | 10-19/32 | 12-15/16   4- 9/16 | 5-15/16 |
  |_________|_________|__________|__________|_________|_________|


The dimensions given for diameter at root of threads are also those
for diameter of hole in nuts and diameter of lap drills. All bolts and
studs 3/4 in. diameter and above, screwed into boilers, have 12
threads per inch, sharp thread, a taper of 1/16 in. per 1 inch; tap
drill should be 9/64 in. less than normal diameter of bolts.

The table is based upon the following general formulæ for certain
dimensions:

  Short diam. rough nut or head = 11/2 diam. of bolt + 1/8.
       "   finished nut or head = 11/2 diam. of bolt + 1/16.
  Thickness rough nut = diameter of bolt.
  Thickness finished nut = diameter of bolt - 1/16.
  Thickness rough head = 1/2 short diameter.
  Thickness finished head = diameter of bolt - 1/16.

       *       *       *       *       *




AN ENGLISH RAILWAY FERRY BOAT.


[Illustration: AN ENGLISH RAILWAY FERRY BOAT.]

The illustrations above represent a double screw steam ferry boat for
transporting railway carriages, vehicles, and passengers, etc.,
designed and constructed by Messrs. Edwards and Symes, of Cubitt Town,
London. The hull is constructed of iron, and is of the following
dimensions: Length 60 ft.; beam 16 ft.; over sponsons 25 ft. The
vessel was fitted with a propeller, rudder, and steering gear at each
end, to enable it to run in either direction without having to turn
around. The boat was designed for the purpose of working the train
service across the bay of San Juan, in the island of Puerto Rico, and
for this purpose a single line of steel rails, of meter gauge, is laid
along the center of the deck, and also along the hinged platforms at
each end. In the engraving these platforms are shown, one hoisted up,
and the other lowered to the level of the deck. When the boat is at
one of the landing stages, the platform is lowered to the level of the
rails on the pier, and the carriages and trucks are run on to the deck
by means of the small hauling engine, which works an endless chain
running the whole length of the deck. The trucks, etc., being on
board, the platform is raised by means of two compact hand winches
worked by worm and worm-wheels in the positions shown; thus these two
platforms form the end bulwarks to the boat when crossing the bay. On
arriving at the opposite shore the operation is repeated, the other
platform is lowered, and the hauling engine runs the trucks, etc., on
to the shore. With a load of 25 tons the draught is 4 ft.

The seats shown on the deck are for the convenience of foot
passengers, and the whole of the deck is protected from the sun of
that tropical climate by a canvas awning. The steering of the vessel
is effected from the bridge at the center, which extends from side to
side of the vessel, and there are two steering wheels with independent
steering gear for each end, with locking gear for the forward rudder
when in motion. The man at the wheel communicates with the engineer by
means of a speaking tube at the wheel. There is a small deck house for
the use of deck stores, on one side of which is the entrance to the
engine room. The cross battens, shown between the rails, are for the
purpose of horse traffic, when horses are used for hauling the trucks,
or for ordinary carts or wagons. The plan below deck shows the
arrangement of the bulkheads, with a small windlass at each end for
lifting the anchors, and a small hatch at each side for entrance to
these compartments. The central compartment contains the machinery,
which consists of a pair of compound surface condensing engines, with
cylinders 11 in. and 20 in. in diameter; the shafting running the
whole length of the vessel, with a propeller at each end. Steam is
generated in a steel boiler of locomotive form, so arranged that the
funnel passes through the deck at the side of the vessel; and it is
designed for a working pressure of 100 lb. per square inch. This
boiler also supplies steam for the small hauling engine fixed on the
bulkhead. Light to this compartment is obtained by means of large side
scuttles along each side of the boat and glass deck lights, and the
iron grating at the entrance near the deck house. This boat was
constructed in six pieces for shipment, and the whole put together in
the builders' yard. The machinery was fixed, and the engine driven by
steam from its own boiler, then the whole was marked and taken
asunder, and shipped to the West Indies, where it was put together and
found to answer the purpose intended.--_Engineering._

       *       *       *       *       *

[For THE SCIENTIFIC AMERICAN.]




THE PROBLEM OF FLIGHT, AND THE FLYING MACHINE.


As a result of reading the various communications to the SCIENTIFIC
AMERICAN and SUPPLEMENT, and _Van Nostrand's Engineering Magazine_,
including descriptions of proposed and tested machines, and the
reports of the British Aeronautical Society, the writer of the
following concludes:

That, as precedents for the construction of a successful flying
machine, the investigation of some species of birds as a base of the
principles of all is correct only in connection with the species and
habits of the bird; that the _general mechanical principles_ of flight
applicable to the _operation_ of the _same unit_ of wing in _all_
species are alone applicable to the flying machine.

That these principles of _operation_ do not demand the principles of
_construction_ of the bird.

That as the wing is in its stroke an arc of a screw propeller's
operation, and in its angle a screw propeller blade, its animal
operation compels its reciprocation instead of rotation.

That the swifter the wing beat, the more efficient its effect per unit
of surface, the greater the load carried, and the swifter the flight.

That the screw action being, in full flight, that of a screw propeller
whose axis of rotation forms a slight angle with the vertical, the
distance of flight per virtual "revolution" of "screw" wing far
exceeds the pitch distance of said "screw."

That consequently a bird's flight answers to an iceboat close hauled;
the wing _force_ answering to the _wind_, the wing _angle_ to the
_sail_, the bird's _weight_ to the leeway fulcrum of the _ice_, and
the passage across direction of the _wing_ flop to the fresh _moving_
"inertia" of the wind, both yielding a maximum of force to bird or
iceboat.

That the speed of _reciprocation_ of a fly's _wing_ being equivalent
to a _screw rotation_ of 9,000 per minute, proves that a _screw_ may
be run at this speed without losing efficiency by centrifugal vacuum.

That as the _object_ of wing or screw is to mount upon the inertia of
the particles of a mobile fluid, and as the rotation of steamship
propellers in water--a fluid of many times the inertia of air--is
_already_ in _excess_ of the highest speed heretofore tried in the
propellers of moderately successful flying machines, it is plain that
the speed employed in _water_ must be many times exceeded in _air_.

That with a _sufficient_ speed of rotation, the supporting power of
the inertia of air must _equal_ that of _water_.

That as mere speed of rotation of propeller _shaft_, minus blades,
must absorb but a small proportion of power of engine, the addition of
blades will not cause more resistance than that actually encountered
from inertia of air.

That this must be the measure of load lifted.

That without _slip_ of screw, the actual _power_ expended, will be
little in _excess_ of that required to support the machine in _water_,
with a slower rotation of screw.

That in case the same _power_ is expended in water or air, the only
difference will lie in the sizes and speed of engines or screws.

That the _greater_ the speed, the _less_ weight of engine, boiler, and
screw must be, and the stronger their construction.

That, in consequence, solid metal worked down, instead of bolts and
truss work, must be used.

That as the bird wing is a screw in action, and acts _directly_
between the inertias of the load and the air, the position and
operation of the screw, to the load, must imitate it.

That, in consequence, machines having wing planes, driven _against_
one inertia of air by screws acting in the line, of flight against
another inertia of air, lose fifty per cent. of useful effect, besides
exposing to a head wind the cross section of the stationary screw wing
planes and the rotating screw discs; and supporting the dead weight of
the wing planes, and having all the screw slip in the line of flight,
and carrying slow and heavy engines.

That as a result of these conclusions, the supporting and propelling
power should be expressed in the rotation of screws combining both
functions, the position of whose planes of rotation to a fixed
horizontal line of direction determines the progress and speed of
machine upon other lines.

That the whole weight carried by the screws should be at all times
exactly below the center of gravity of the plane of support, whether
it be horizontal or inclined.

That while the _permanently_ positioned weight, such as the engines,
frame, holding screws, etc., may be rigidly connected to or around the
screw plane of support, the variable positioned weight, such as the
passenger and the car, should be connected by a _flexible joint_ to
the said plane of support.

Consequently, the car may oscillate without altering its weight
position under center of supporting plane, thus avoiding an
involuntary alteration of speed or direction of flight.

That to steer a machine so constructed, it is merely necessary to move
the point of attachment of car to _machine_ proper, out of the center
of plane of support in the desired direction, and thus cause the plane
of support or rotation of propellers to incline in that direction.

That the reservoir of power, the boiler, etc., should be placed in the
_car_, and steam carried to engines through joint connecting car with
machine.

That at present material exists, and power also, of sufficient
lightness and strength to admit of a machine construction capable of a
limited successful flight in any fair wind and direction.

That such _machine_ once built, the finding of a _power_ for long
flights will be easy, if not already close at hand in _electricity_.

That the _easiest_ design for such _actual machine_ should be adopted,
leaving the adaptation of the principles involved to the making of
more perfect machines, to a time after the success of the _first_.

That such design may be a propeller, and its engine at each end of a
steel frame tube, supporting tube horizontally, a car to be supported
by a universal joint from center of said tube, and the joint apparatus
movable along the tube or a short distance transverse to it, to alter
position of center of gravity.

That the machine so built might traverse the water as well as air.

       *       *       *       *       *




THE LONGHAIRED POINTER MYLORD.


Pointers are trained to search for game, and to indicate that they
have found the same by standing motionless in front of it, and, when
it has been shot, to carry the game to the huntsman. Several kinds of
pointers are known, such as smooth, longhaired, and bushyhaired
pointers. The smoothhaired pointers are better for hunting on high
land, whereas the longhaired or bushyhaired dogs are better for low,
marshy countries, crossed by numerous streams, etc. Mylord, the dog
represented in the annexed cut taken from the _Illustrirte Zeitung_,
is an excellent specimen of the longhaired pointer, and is owned by
Mr. G. Borcher, of Braunschweig, Germany.

[Illustration: THE LONGHAIRED POINTER, "MYLORD."]

The longhaired pointer is generally above the medium size, powerful,
somewhat longer than the normal dog, the body is narrower and not
quite as round as that of the smoothhaired dog, and the muscles of the
shoulders and hind legs are not as well developed and not as
prominent. The head and neck are erect, the head being specially long,
and the tail is almost horizontal to the middle, and then curves
upward slightly. The long hair hangs in wavy lines on both sides of
his body. The expression of his face is intelligent, bright, and
good-natured, and his step is light and almost noiseless.

The pointer is specially valuable, as it can be employed for many
different purposes; he is an excellent dog for the woods, for the
woodsman and hunter who uses only one dog for different kinds of game.
The intelligence of the German pointer is very great, but he does not
develop as rapidly as the English dog, which has been raised for
generations for one purpose only. The German pointer hunts very
slowly, but surely. It is not difficult to train this dog, but he
cannot be trained until he has reached a certain age.

       *       *       *       *       *




LUNAR HEAT.

By Professor C.A. YOUNG.


One of the most interesting inquiries relating to the moon is that
which deals with the heat she sends us, and the probable temperature
of her surface. The problem seems to have been first attacked by
Tschirnhausen and La Hire, about 1700; and they both found, that even
when the moon's rays were concentrated by the most powerful
burning-lenses and mirrors they could obtain, its heat was too small
to produce the slightest perceptible effect on the most delicate
thermometers then known. For more than a hundred years, this was all
that could be made out, though the experiment was often repeated.

It was not until 1831 that Melloni, with his newly-invented
"thermopile," [1] succeeded in making the lunar heat sensible; and in
1835, taking his apparatus to the top of Vesuvius, he obtained not
only perceptible, but measurable, results, getting a deviation of four
or five divisions of his galvanometer.

   [Footnote 1: Probably most of our readers know that the
   thermopile consists of a number of little bars of two different
   metals, connected in pairs, and having the ends joined in a
   conducting circuit with a galvanometer. If, now, one set of the
   junctures is heated more than the other set, a current of
   electricity will be generated, which will affect the
   galvanometer. The bars are usually made of bismuth and antimony
   though iron and German silver answer pretty well. They are
   commonly about half or three-quarters of an inch long, and about
   half as large as an ordinary match. The "pile" is made of from
   fifty to a hundred such bars packed closely, but insulated by
   thin strips of mica, except just at the soldered junctions. With
   an instrument of this kind and a very delicate galvanometer,
   Professor Henry found that the heat from a person's face could be
   perceived at a distance of several hundred feet. There is
   however, some doubt whether he was not mistaken in respect to
   this extreme sensitiveness.]

Others repeated the experiment several times between this time and
1856, with more or less success; but, so far as I know, the first
quantitative result was that obtained in 1856 by Piazzi Smyth during
his Teneriffe expedition. On the top of the mountain, at an elevation
of ten thousand feet, he found that the moon's rays affected his
thermopile to the same extent as a standard candle ten feet away.
Marie Davy has since shown that this corresponds to a heating effect
of about 1/1300 of a Centigrade degree.

The subject was resumed in 1868 by Lord Rosse in Ireland; and a long
series of observations, running through several years, was made by the
aid of his three-foot reflector (not the great _six_-foot instrument,
which is too unwieldy for such work). The results of his work have,
until very recently, been accepted as authoritative. It should be
mentioned that, at about the same time, observations were also made at
Paris by Marie Davy and Martin; but they are generally looked upon
merely as corroborative of Rosse's work, which was more elaborate and
extensive. Rosse considered that his results show that the heat from
the moon is mainly _obscure, radiated_ heat; the _reflected_ heat,
according to him, being much less in amount.

A moment's thought will show that the moon's heat must consist of two
portions. First, there will be _reflected solar heat_. The amount and
character of this will depend in no way upon the temperature of the
moon's surface, but solely upon its reflecting power. And it is to be
noted that moon-_light_ is only a part of this reflected radiant
energy, differing from the invisible portion of the same merely in
having such a wave-length and vibration period as to bring it within
the range of perception of the human eye.

The second portion of the heat sent us by the moon is that which she
emits on her own account as a warm body--warmed, of course, mainly, if
not entirely, by the action of the sun. The amount of _this_ heat will
depend upon the temperature of the moon's surface and its radiating
power; and the temperature will depend upon a number of things
(chiefly heat-absorbing power of the surface, and the nature and
density of the lunar atmosphere, as well as the supply of heat
received from the sun), being determined by a balance between give and
take. So long as more heat is received in a second than is thrown off
in the same time, the temperature will rise, and _vice versa_.

It is to be noted, further, that this second component of the moon's
thermal radiance must be mainly what is called "obscure" or dark heat,
like that from a stove or teakettle, and characterized by the same
want of penetrative power. No one knows why at present; but it is a fact
that the heat-radiations from bodies at a low temperature--radiations
of which the vibrations are relatively slow, and the wave-length
great--have no such power of penetrating transparent media as the
higher-pitched vibrations which come from incandescent bodies. A great
part, therefore, of this contingent of the lunar heat is probably
stopped in the upper air, and never reaches the surface of the earth
at all.

Now, the thermopile cannot, of course, discriminate directly between
the two portions of the lunar heat; but to some extent it does enable
us to do so indirectly, since they vary in quite a different way with
the moon's age. The simple _reflected_ heat must follow the same law
as moonlight, and come to its maximum at full moon. The _radiated_
heat, on the other hand, will reach its maximum when the average
temperature of that part of the moon's surface turned toward the earth
is highest; and this must be some time after full moon, for the same
sort of reasons that make the hottest part of a summer's day come two
or three hours after noon.

The conclusion early reached by Lord Rosse was that nearly all the
lunar heat belonged to the second category--dark heat _radiated_ from
the moon's warmed surface, the _reflected_ portion being comparatively
small--and he estimated that the temperature of the hottest parts of
the moon's surface must run as high as 500° F.; well up toward the
boiling-point of mercury. Since the lunar day is a whole month long,
and there are never any clouds in the lunar sky, it is easy to imagine
that along toward two or three o'clock in the lunar afternoon (if I
may use the expression), the weather gets pretty hot; for when the sun
stands in the lunar sky as it does at Boston at two P.M., it has been
shining continuously for more than two hundred hours. On the other
hand, the coldest parts of the moon's surface, when the sun has only
just risen after a night of three hundred and forty hours, must have a
temperature more than a hundred degrees below zero.

Lord Rosse's later observations modified his conclusions, to some
extent, showing that he had at first underestimated the percentage of
simple reflected heat, but without causing him to make any radical
change in his ideas as to the maximum heat of the moon's surface.

For some time, however, there has been a growing skepticism among
astronomers, relating not so much to the correctness of his measures
as to the computations by which he inferred the high percentage of
obscure radiated beat compared with the reflected heat, and so deduced
the high temperature of lunar noon.

Professor Langley, who is now engaged in investigating the subject,
finds himself compelled to believe that the lunar surface never gets
even comfortably warm--because it has no blanket. It receives heat, it
is true, from the sun, and probably some twenty-five or thirty per
cent. more than the earth, since there are no clouds and no air to
absorb a large proportion of the incident rays; but, at the same time,
there is nothing to retain the heat, and prevent the radiation into
space as soon as the surface begins to warm. We have not yet the data
to determine exactly how much the temperature of the lunar rocks would
have to be raised above the absolute zero (-273° C. or -459° F.) in
order that they might throw off into space as much heat in a second as
they would get from the sun in a second. But Professor Langley's
observations, made on Mount Whitney at an elevation of fifteen
thousand feet, when the barometer stood at seventeen inches
(indicating that about fifty-seven per cent. of the air was still
above him), showed that rocks exposed to the perpendicular rays of the
sun were not heated to any such extent as those at the base of the
mountain similarly exposed; and the difference was so great as to make
it almost certain that a mass of rock not covered by a reasonably
dense atmosphere could never attain a temperature of even 200° or 300°
F. under solar radiation, however long continued.

It must, in fact, be considered at present extremely doubtful whether
any portion of the moon's surface ever reaches a temperature as high
as -100°.

The subject, undoubtedly, needs further investigation, and it is now
receiving it. Professor Langley is at work upon it with new and
specially constructed apparatus, including a "bolometer" so sensitive
that, whereas previous experimenters have thought themselves fortunate
if they could get deflections of ten or twelve galvanometric divisions
to work with, he easily obtains three or four hundred. We have no time
or space here to describe Professor Langley's "bolometer;" it must
suffice to say that it seems to stand to the thermopile much as that
does to the thermometer. There is good reason to believe that its
inventor will be able to advance our knowledge of the subject by a
long and important step; and it is no breach of confidence to add that
so far, although the research is not near completion yet, everything
seems to confirm the belief that the radiated heat of the moon,
instead of forming the principal part of the heat we get from her, is
relatively almost insignificant, and that the lunar surface now never
experiences a _thaw_ under any circumstances.

Since the superstition as to the moon's influence upon the wind and
weather is so widespread and deep seated, a word on that subject may
be in order. In the first place, since the total heat received from
the moon, even according to the highest determination (that of Smyth),
is not so much as 0.00001 of that received from the sun, and since the
only hold the moon has on the earth's weather is through the heat she
sends us (I ignore here the utterly insignificant atmospheric _tide_),
it follows necessarily that her influence _must_ be very trifling. In
the next place, all carefully collated observations show that it _is_
so, and not only trifling, but generally absolutely insensible.

For example, different investigators have examined the question of
nocturnal cloudiness at the time of full moon, there being a prevalent
belief that the full moon "eats up" light clouds. On comparing thirty
or forty years' observations at each of several stations (Greenwich.
Paris, etc.), it is found that there is no ground for the belief. And
so in almost every case of imagined lunar meteorological influence. As
to the coincidence of weather changes with changes of the moon, it is
enough to say that the idea is absolutely inconsistent with that
progressive movement of the "weather" across the country from west to
east, with which the Signal Service has now made us all so familiar.

Princeton, April 12, 1884.

       *       *       *       *       *




APPLE TREE BORERS.


The apple tree borers have destroyed thousands of trees in New
England, and are likely to destroy thousands more. There are three
kinds of borers which assail the apple tree. The round headed or two
striped apple tree borer, _Saperda candida_, is a native of this
country, infesting the native crabs, thorn bushes, and June berry. It
was first described by Thomas Say, in 1824, but was probably widely
distributed before that. In his "Insects Injurious to Fruit," Prof.
Saunders thus describes the borer:

"In its perfect state it is a very handsome beetle, about
three-quarters of an inch long, cylindrical in form, of a pale brown
color, with two broad, creamy white stripes running the whole length
of its body; the face and under surface are hoary white, the antennæ
and legs gray. The females are larger than the males, and have shorter
antennæ. The beetle makes its appearance during the months of June and
July, usually remaining in concealment during the day, and becoming
active at dusk. The eggs are deposited late in June and during July,
one in a place, on the bark of the tree, near its base. Within two
weeks the young worms are hatched, and at once commence with their
sharp mandibles to gnaw their way through the outer bark to the
interior. It is generally conceded that the larvæ are three years in
reaching maturity. The young ones lie for the first year in the
sapwood and the inner bark, excavating flat, shallow cavities, about
the size of a silver dollar, which are filled with their sawdust-like
castings. The holes by which they enter being small are soon filled
up, though not until a few grains of castings have fallen from them.
Their presence may, however, often be detected in young trees from the
bark becoming dark colored, and sometimes dry and dead enough to
crack."

On the approach of winter, it descends to the lower part of its
burrow, where it remains inactive until spring. The second season it
continues its work in the sapwood, and in case two or three are at
work in the same tree may completely girdle it, thus destroying it.
The third year it penetrates to the heart of the tree, makes an
excavation, and awaits its transformation. The fourth spring it comes
forth a perfect beetle, and lays its eggs for another generation.


THE FLAT-HEADED BORER.

The flat-headed apple tree borer, _Chrysobothris femorata_, is also a
native of this country. It is a very active insect, delights to bask
in the hot sunshine; runs up and down the tree with great rapidity,
but flies away when molested. It is about half an inch in length. "It
is of a flattish, oblong form, and of a shining, greenish black color,
each of its wing cases having three raised lines, the outer two
interrupted by two impressed transverse spots of brassy color dividing
each wing cover into three nearly equal portions. The under side of
the body and legs shine like burnished copper; the feet are shining
green." This beetle appears in June and July, and does not confine its
work to the base of the tree, but attacks the trunk in any part, and
sometimes the larger branches. The eggs are deposited in cracks or
crevices of the bark, and soon hatch. The young larva eats its way
through the bark and sapwood, where it bores broad and flat channels,
sometimes girdling and killing the tree. As it approaches maturity, it
bores deeper into the tree, working upward, then eats out to the bark,
but not quite through the bark, where it changes into a beetle, and
then cuts through the bark and emerges to propagate its kind. This
insect is sought out when just beneath the bark, and devoured by
woodpeckers and insect enemies.

Another borer, the long-horned borer, _Leptostylus aculifer_, is
widely distributed, but is not a common insect, and does not cause
much annoyance to the fruit grower. It appears in August, and deposits
its eggs upon the trunks of apple trees. The larvæ soon hatch, eat
through the bark, and burrow in the outer surface of the wood just
under the bark.


PROTECTION AGAINST BORERS.

The practical point is, What remedies can be used to prevent the
ravages of the borers? The usual means of fighting the borers is, to
seek after them in the burrows, and try to kill them by digging them
out, or by reaching them with a wire. This seems to be the most
effectual method of dealing with them after they have once entered the
tree, but the orchardist should endeavor to prevent the insects from
entering the tree. For this purpose, various washes have been
recommended for applying to the tree, either for destroying the young
larvæ before they enter the bark, or for preventing the beetles
depositing their eggs. It has been found that trees which have been
coated with alkaline washes are avoided by beetles when laying their
eggs. Prof. Saunders recommends that soft soap be reduced to the
consistency of a thick paint, by the addition of a strong solution of
washing soda in water, and be applied to the bark of the tree,
especially about the base or collar, and also extended upward to the
crotches where the main branches have their origin. It should be
applied in the evening of a warm day, so that it may dry and form a
coating not easily dissolved by the rain. This affords a protection
against all three kinds of borers. It should be applied early in June,
before the beetles begin to lay their eggs, and again in July, so as
to keep the tree well protected.

Hon. T.S. Gold, of Connecticut, at a meeting of the Massachusetts
State Board of Agriculture, in regard to preventing the ravages of the
borer, said:

"A wash made of soap, tobacco water, and fresh cow manure mingled to
the consistency of cream, and put on early with an old broom, and
allowed to trickle down about the roots of the tree, has proved with
me a very excellent preventive of the ravages of the borer, and a
healthful wash for the trunk of the tree, much to be preferred to the
application of lime or whitewash, which I have often seen applied, but
which I am inclined to think is not as desirable an application as the
potash, or the soda, as this mixture of soft soap and manure."

J.B. Moore, of Concord, Mass., at the same meeting said, in regard to
the destruction of the borer:

"I have found, I think, that whale oil soap can be used successfully
for the destruction of that insect. It is a very simple thing; it will
not hurt the tree if you put it on its full strength. You can take
whale oil soap and dilute until it is about as thick as paint, and put
a coating of it on the tree where the holes are, and I will bet you
will never see a borer on that tree until the new crop comes. I feel
certain of it, because I have done it."

For borers, tarred paper 1 or 2 feet wide has been recommended to be
wrapped about the base of the trunk of the tree, the lower edge being
1 or 2 inches below the surface of the soil. This prevents the
two-striped borer from laying its eggs in the tree, but would not be
entirely effectual against the flat-headed borer, which attacks any
part of the trunk and the branches. By the general use of these means
for the prevention of the ravages of the borers, the damages done by
these insects could be brought within very narrow limits, and hundreds
of valuable apple trees saved.

H. REYNOLDS, M.D.

Livermore Falls, Me.

       *       *       *       *       *




KEFFEL'S GERMINATING APPARATUS.


The apparatus represented in the annexed cut is designed to show the
quality of various commercial seeds, and make known any fraudulent
adulterations that they may have undergone. It is based upon a direct
observation, of the germination of the seeds to be studied.

[Illustration: KEFFEL'S GERMINATING APPARATUS.]

The apparatus consists of a cylindrical vessel containing water to the
height of 0.07 m. Above the water is a germinating disk containing 100
apertures for the insertion of the seeds to be studied, the
germinating end of the latter being directed toward the water. After
the seeds are in place the disk is filled with damp sand up to the top
of its rim, and the apparatus is closed with a cover which carries in
its center a thermometer whose bulb nearly reaches the surface of the
water.

The apparatus is then set in a place where the temperature is about
18°, and where there are no currents of air. An accurate result is
reached at the end of about twenty or twenty-four hours. As the
germinating disk contains 100 apertures for as many seeds, it is only
necessary to count the number of seeds that have germinated in order
to get the percentage of fresh and stale ones.

The aqueous vapor that continuously moistens all the seeds, under
absolutely identical conditions for each, brings about their
germination under good conditions for accuracy and comparison. If it
be desired to observe the starting of the leaves, it is only necessary
to remove the cover after the seeds have germinated.

This ingenious device is certainly capable of rendering services to
brewers, distillers, seedsmen, millers, farmers, and gardeners, and it
may prove useful to those who have horses to feed, and to amateur
gardeners, since it permits of ascertaining the value and quality of
seeds of every nature.--_La Nature._

       *       *       *       *       *




MILLET.


The season is now at hand when farmers who have light lands, and who
may possibly find themselves short of fodder for next winter feeding,
should prepare for a crop of millet. This is a plant that rivals corn
for enduring a drought, and for rapid growth. There are three popular
varieties now before the public, besides others not yet sufficiently
tested for full indorsement--the coarse, light colored millet, with a
rough head, Hungarian millet, with a smooth, dark brown head, yielding
seeds nearly black, and a newer, light colored, round seeded, and
later variety, known as the golden millet.

Hungarian millet has been the popular variety with us for many years,
although the light seeded, common millet is but slightly different in
appearance or value for cultivation. They grow in a short time, eight
weeks being amply sufficient for producing a forage crop, though a
couple of weeks more would be required for maturing the seed. Millet
should not be sown in early spring, when the weather and ground are
both cold. It requires the hot weather of June and July to do well;
then it will keep ahead of most weeds, while if sown in April the
weeds on foul land would smother it.

Millet needs about two months to grow in, but if sowed late in July it
will seem to "hurry up," and make a very respectable showing in less
time. We have sown it in August, and obtained a paying crop, but do
not recommend it for such late seeding, as there are other plants that
will give better satisfaction. Golden millet has been cultivated but a
few years in this country, and as yet is but little known, but from a
few trials we have been quite favorably impressed with it. It is
coarser than the other varieties, but cattle appear to be very fond of
it nevertheless. It resembles corn in its growth nearly as much as
grass, and, compared with the former, it is fine and soft, and it
cures readily, like grass, and may be packed away in hay mows with
perfect safety. It is about two weeks later than the other millets,
and consequently cannot be grown in quite so short a time, although it
may produce as much weight to the acre, in a given period, as either
of the other more common varieties. A bushel of seed per acre is not
too much for either variety of millet.--_N.E. Farmer._

       *       *       *       *       *


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