Produced by Don Kretz, Juliet Sutherland, Charles Franks and the DP Team




[Illustration]




SCIENTIFIC AMERICAN SUPPLEMENT NO. 483




NEW YORK, APRIL 4, 1885

Scientific American Supplement. Vol. XIX, No. 483.

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.--The Determination of
      Graphite in Minerals.--By J.B. MACKINTOSH.

      Sulphocyanide of Potassium.

      Sugar Nitro-glycerine.

      On Remelting of Cast Iron.

      The Hardness of Metals.


II.   ENGINEERING, ETC.--The Jet Ventilator. 4 figures.
      Feeding Boilers at the Bottom. 2 figures.

      The Honigmann Fireless Engine.--The fireless working of steam
      engines by means of a solution of hydrate of soda.--With
      several figures and diagrams.

      Simple Methods of Calculating Stress in Girders.--By CH. LEAN.--With
      full page of illustrations.

      A Spring Motor.

      Steam Yachts.


III.  TECHNOLOGY.--Foucault's Apparatus for Manufacturing
      Illuminating Gas and Hydrogen. 2 figures.

      The Circle Divider.

      Soluble Glass.--Process of manufacture.--Use.

      Iron Printing and Microscopic Photography.--Formulas for
      printing solutions.--Compound negatives.

      Practical Directions for Making Lantern Transparencies.--By
      T.N. ARMSTRONG.

      Casting Chilled Car Wheels. 6 figures.


IV.   ELECTRICITY, ETC.--Electricity and Prestidigitation.
      2 figures.

      Portable Electric Safety Lamp. 6 figures.

      The Electric Discharge and Spark Photographed Directly without
      an Objective. 6 engravings.


V.    PHYSICS, ETC.--The True Constant of Gravity.

      Origin of Thunder Storms.

      Physics without Apparatus.--Manufacture of illuminating
      gas.--Elasticity of bodies. 2 figures.

      Scientific Amusements.--Dance of electrified puppets.--Silhouette
      portraits. 2 figures.

      A Sunshine Recorder. 2 figures.


VI.   MEDICINE, HYGIENE, ETC.--How Cholera is Spread.

      Sulphurous Acid and Sulphide of Carbon as Disinfecting
      Agents.--Methods of burning the same.


VII.  MISCELLANEOUS.--Improvised Toys.--With numerous illustrations.

      The Æolian Harp.--Kircher's harp, made in 1558.--Frost and
      Kastner's harp.--Manner of making the harps. 4 figures.

      How to Break a Cord with the Hands. 1 figure.

      An Aquatic Velocipede for Duck Hunting. 2 engravings.

      Skeleton of a Bear Found in a Cave in Styria, Austria.


VIII. BIOGRAPHY.--Theodor Billroth, Prof, of Surgery at Vienna.--With
      portrait.

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ACKNOWLEDGMENT.


The illustrations and descriptions we give this week, entitled "How to
Break a Cord," "Prestidigitation," "Circle Divider," "Sulphurous Acid,"
"Production of Gas," "Aquatic Velocipede," "Several Toys," "Scientific
Amusements," are from our excellent contemporary _La Nature_.

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THEODOR BILLROTH, PROFESSOR OF SURGERY AT VIENNA.


The well known surgeon, Theodor Billroth, was born on the island of Rügen
in 1829. He showed great talent and liking for music, and it was the wish
of his father, who was a minister, that he should cultivate this taste
and become an artist; but the great masters of medicine, Johannes
Mueller, Meckel v. Hemsbach, R. Wagner, Traube, and Schönlein, who were
Billroth's instructors at Greifswald, Göttingen, and Berlin, discovered
his great talent for surgery and medicine, and induced him to adopt this
profession. It was particularly the late Prof. Baum who influenced
Billroth to make surgery a special study, and he was Billroth's first
special instructor.

In 1852 Billroth received his degree as doctor at the University of
Berlin. After traveling for one year, and spending part of his time in
Vienna and Paris, he was appointed assistant in the clinique of B. von
Langenbeck, Berlin. At this time he published his works on pathological
histology ("Microscopic Studies on the Structure of Diseased Human
Tissues") which made him so well known that he was appointed a professor
of pathology at Greifswald in 1858. Mr. Billroth did not accept that
call, and was appointed professor of surgery at Zurich in 1860, and
during that time his wonderful operations gave him a world-wide
reputation. In 1867 the medical faculty of the Vienna University
concluded to appoint Billroth as successor to Prof. Schuh, which position
he still fills.

[Illustration: THEODOR BILLROTH.]

Billroth is a master of surgical technique, and his courage and composure
increase with the difficulty of the operation. He always makes use of the
most simple apparatus and instruments, and follows a theoretically
scientific course which he has never left since he adopted surgery as a
profession, and by which he has directed surgery into entirely new
channels. He has given special attention to the study of the healing of
wounds, the development of swellings and tumors, and the treatment of
wounds in relation to decomposition and the formation of proud flosh. He
has had wonderful success in performing plastic operations on the face,
such as the formation of new noses, lips, etc., from flesh taken from
other parts of the body or from the face. Although Billroth devoted much
of his time to the solution of theoretical problems, he has also been
very successful as an operator. He has removed diseased larynxes,
performed dangerous goiter operations, and successfully removed parts of
the oesophagus, stomach, and intestines.

Billroth has been very careful in the selection of his scholars, and many
of them are now professors of surgery and medicine in Germany, Belgium,
and Austria. They all honor and admire him, his courage, his character,
his humane treatment of the sick and suffering, arid his amiability.

The accompanying portrait is from the _Illustrirte Zeitung._

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HOW CHOLERA IS SPREAD.


DR. JOHN C. PETERS, of this city, in a recent contribution to the
_Medical Record_, gives the following interesting particulars:

I have read many brilliant essays of late on these topics, but not with
unalloyed pleasure, for I believe that many writers have fallen into
errors which it is important to correct. No really well informed person
has believed for a long time that carbolic alcohol will destroy the
cholera poison; but many fully and correctly believe that real germicides
will. It has been known since 1872 that microbes, bacilli, and bacteria
could live in very strong solutions of carbolic alcohol, and that the
dilute mineral acids, tannin, chloride, corrosive sublimate, and others
would kill them.

In 1883 cholera did not arise alone in Egypt from filth, but from
importation. It did not commence at Alexandria, but at Damietta, which is
the nearest Nile port to Port Said, which is the outlet of the Suez
Canal. There were 37,500 deaths from cholera in the Bombay Presidency in
1883. Bombay merchants came both to Port Said and Damietta to attend a
great fair there, to which at least 15,000 people congregated, in
addition to the 35,000 inhabitants. The barbers who shave and prepare the
dead are the first registrars of vital statistics in many Egyptian towns,
and the principal barber of Damietta was among the first to die of
cholera; hence all the earliest records of deaths were lost, and the more
fatal and infective diarrhoeal cases were never recorded. Next the
principal European physician of Damietta had his attention called to the
rumors of numerous deaths, and investigated the matter, to find that
cases of cholera had occurred in May, whereas none had been reported
publicly until June 21. A _zadig_, or canal, runs through Damietta from
one branch of the Nile to another, and this is the principal source of
the water supply.

Mosques and many houses are on the banks of this canal, and their
drainage goes into it. Every mosque has a public privy, and also a tank
for the ablution, which all good Mohammedans must use before entering a
holy place. There was, of course, great choleraic water contamination,
and a sudden outburst of cholera took place. The 15,000 people who came
to the fair were stampeded out of Damietta, together with about 10,000 of
the inhabitants, who carried the disease with them back into Egypt. Then
only was a rigid quarantine established, and a cordon put round Damietta
to keep everybody in, and let no one go out, neither food, medicines,
doctors, nor supplies of any kind. Such is nearly the history of every
town attacked in Egypt in 1883.

When the pestilence had been let out _en masse_, severe measures were
taken to keep it in Cairo, for up the Nile was attacked long before
Alexandria suffered. This cholera broke out, as it almost always does in
Egypt, when the river Nile is low and the water unusually bad. It
disappeared like magic, as it always does in Egypt, when the Nile rises
and washes all impurities away. There had been little or no cholera in
Egypt since 1865, and there had often been as much filth as in 1883. It
has never become endemic there, as it is a rainless country and generally
too dry for the cholera germ to thrive.

Marseilles had a small outbreak of cholera in the fall of 1883, probably
derived from Egypt, which she carefully concealed. In addition, cholera
was also brought to Toulon from Tonquin by the Sarthe and other vessels.
Toulon concealed her cholera for at least seventeen days, and did not
confess it until it had got such headway that it could no longer be
concealed. At least twenty thousand Italians fled from Toulon and
Marseilles, and others were brought away in transports by the Italian
government. Rome refused to receive any fugitives; Genoa and Naples
welcomed them. There were at least three large importations into Naples.
The outbreak in Genoa was connected with washing soiled cholera clothes
in one of the principal water supplies of the city, and Naples has many
privy pits and surface wells. These privies, or _pozzis_, in the poorer
parts of many Italian towns, are in the yards or cellars, and are so
arranged that when they overflow, the surplusage is carried through
drains or gutters into the streets.

In the lowest parts of Toulon there were no privies at all, and the
people emptied their chamberpots into the streets every morning. This
flowed down toward the harbor, which is almost tideless. Toulon always
has much typhoid fever from this cause; but no cholera unless it is
imported.

The great outbreaks of cholera in Paris in 1832, 1848, 1854, and 1865
have been explained at last by Dr. Marcy. The canal de l'Ourcq is one of
the principal water sources of Paris. The market boats or vessels upon it
and at La Villette are so numerous that Marseilles and Havre alone
outrank it in shipping. The parts of Paris which are always most severely
attacked with cholera, and where the most typhoid fever prevails, are
supplied with this water, into which not only all the filth of the boats
goes, but many sewers empty.

I agree with all that is generally said about civic filth favoring the
spread of cholera, but it does not generate, but only supplies the
pabulum for the germs. I believe as long as the Croton water is kept pure
there can be no general outbreak of cholera in New York, only isolated
cases, or at most a few in each house, and those only into which
diarrhoeal cases come, or soiled clothes are brought; that it will not
spread even to the next house, and that there are no pandemic waves of
cholera.

I think it impossible to pump New York dock water into the sewers, and
that it would be very injurious if it could be done. Almost all our
sewers empty into the docks, and the water there is of the foulest kind.
I do not believe in a long quarantine, and think that of the Dutch is the
best. They only detained the sick, but took the addresses of all who were
let through, or kept back all their soiled clothing, which they had
washed, disinfected, and sent after their owners in three days.

St. Louis still has 20,000 privy pits and as many surface wells. The
importation of cholera into St. Louis is well proved for 1832, 1848,
1849, 1854, 1866, and 1873. Those who used surface well water suffered
much more than those who drank Mississippi water, however foul that may
have been. The history of cholera in St. Louis has been better and more
accurately written up quite lately by Mr. Robert Moore, civil engineer,
than that of any city in this country. He has kindly given me maps of the
city, with every case marked down, with street and number, for all the
epidemic.

Hypodermic injections of atropine and morphine have failed sadly in many
cases. Subcutaneous injections of large quantities of salt and water,
with some soda, and large rectal injections of tannin and laudanum have
been very successful in Italy. If there is plenty of acid gastric juice
in the stomach, the cholera poison and microbes may be swallowed with
impunity. The worst cases of cholera are produced by drinking large
quantities of cholera contaminated water, when the stomach is empty and
alkaline. I think it probable that large quantities, as much as the
thirst requires, of a weak acid water will prove very beneficial in
cholera. Water slightly acidulated with sulphuric, nitric, or muriatic
acid will probably be the best, but it is hoped that phosphoric, acetic,
and lactic acids will prove equally good. Lemon juice and vinegar are
merely acetates and citrates of potash, and are not as good.

       *       *       *       *       *

It seems that the offensive smells noticed in the English Houses of
Parliament last session have been traced to their source. It is found
that the main sewer of the House of Commons is very large and out of all
proportion to the requirements, is of two different levels, and
discharges into the street sewer within eighteen inches of the bottom of
the latter drain. There is thus a constant backflow of sewage. Another
revelation is that the drain connected with the open furnace in the Clock
Tower, for the purpose of ventilation, is hermetically closed at its
opposite end.

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SULPHUROUS ACID AND SULPHIDE OF CARBON.


Much attention has been paid in recent times to disinfecting agents, and
among these sulphurous acid and sulphide of carbon must be placed in the
list of the most efficient. Mr. Alf. Riche has recently summed up in the
_Journal de Pharmacie et de Chimie_ the state of the question as regards
these two agents, and we in turn shall furnish a few data on the subject
in taking the above named scientist as a guide.

Mr. Dujardin Beaumetz some time ago asked Messrs. Pasteur and Roux's aid
in making some new experiments on the question, and has made known the
result of these to the Academy of Medicine. At the Cochin Hospital he
selected two rooms of 3,530 cubic feet capacity located in wooden sheds.
The walls of these rooms, which were formed of boards, allowed the air to
enter through numerous chinks, although care had been taken to close the
largest of these with paper. In each of the rooms were placed a bed,
different pieces of furniture, and fabrics of various colors. Bromine,
chlorine and sulphate of nitrosyle were successively rejected. Three
sources of sulphurous acid were then experimented with, viz., the burning
of sulphur, liquefied sulphurous acid, and the burning of sulphide of
carbon. The rooms were closed for twenty-four hours, and tubes containing
different proto-organisms, and particularly the comma bacillus made known
by Koch, were placed therein, along with other tubes containing vaccine
lymph. After each experiment these tubes were carried to Mr. Pasteur's
laboratory and compared with others.

[Illustration: FIG. 1.--BURNER FOR SULPHUR.]

The process by combustion of sulphur is the simplest and cheapest. To
effect such combustion, it suffices to place a piece of iron plate upon
the floor of the room, and on this to place bricks connected with sand,
or, what is better, to use a small refractory clay furnace (as advised by
Mr. Pasteur), of oblong form, 8 inches in width by 10 in length, and
having small apertures in the sides in order to quicken combustion.

In order to obtain a complete combustion of the flowers of sulphur, it is
necessary to see to it that the burning is effected equally over its
entire surface, this being easily brought about by moistening the sulphur
with alcohol and then setting fire to the latter. Through the use of this
process a complete and absolute combustion has been obtained of much as
from 18 to 20 grains of sulphur per cubic foot.

In the proportion of 8 grains to the cubic foot, all the different
culture broths under experiment were sterilized save the one containing
the bacteria of charbon. As for the vaccine virus, its properties were
destroyed. This economical process presents but two inconveniences, viz.,
the possibility of fire when the furnace is badly constructed, and the
alteration of such metallic objects as may be in the room. In fact, the
combustion of sulphur is attended with the projection of a few particles
of the substance, which form a layer of metallic sulphide upon copper or
iron objects.

[Illustration: FIG. 2.--CKIANDI BEY'S APPARATUS FOR BURNING CARBON
SULPHIDE.]

The use of liquid sulphurous acid in siphons does not offer the same
inconveniences. These siphons contain about one and a half pounds of
sulphurous acid. The proportion necessary to effect the sterilization of
the culture broths is one siphon per 706 cubic feet. In such a case the
_modus operandi_ is as follows: In the middle of the room is placed a
vessel, which is connected with the exterior by means a rubber tube that
passes through a hole in the door. After the door has been closed, it is
only necessary to place the nozzle of the siphon in the rubber tube, and
to press upon the lever of the siphon valve, to cause the liquid to pass
from the siphon to the interior of the vessel. The evaporation of the
liquid sulphurous acid proceeds very rapidly in the free air. This
process is an exceedingly convenient one; it does away with danger from
fire, and it leaves the gildings and metallic objects that chance to be
in the room absolutely intact. Finally, the acid's power of penetration
appears to be still greater than that which is obtained by the combustion
of sulphur. It has but one drawback, and that is its high price. Each
siphon is sold to the public at the price of one dollar. To
municipalities using sulphurous acid in this form the price would be
reduced to just one-half that figure.

It will be seen, then, that for a room of 3,530 cubic feet capacity the
cost would be $5.00 or $2.50.

The combustion of sulphide of carbon furnishes an abundance of sulphurous
acid, but has hitherto been attended with danger. This, however, has
recently been overcome by the invention of a new burner by Mr. Ckiandi
Bey. The general arrangement of this new apparatus is shown in Figs. 2
and 3.

Mr. Ckiandi's burner consists of an external vessel, A B C D. of tinned
copper, containing a vessel, I H E F, to the sides of which are fixed
three siphons, R, S.

[Illustration: FIG. 3.--SECTION OF THE APPARATUS.]

To operate the burner, we place the cylindrical tube, K L M N, in the
inner vessel, and pour sulphide of carbon into it up to the level _aa_.
This done, we fill the external vessel with water up to the level _bb_.
Thanks to the siphons, the water enters the inner vessel, presses the
sulphide of carbon, which is the heavier, and causes it to rise in the
tube up to the level _a'a',_ where it saturates a cotton wick, which is
then lighted. The upper end of the tube is surmounted with a chimney, PQ.
which quickens the draught.

The combustion may be retarded or quickened at will by causing the level
_bb_ of the water to rise or lower.

The burner is placed in the room to be disinfected, which, after the wick
has been lighted, is closed hermetically. When all the sulphide is burned
it is replaced by water, and the lamp goes out of itself.

The combustion proceeds with great regularity and without any danger. It
takes about five and a half pounds for a room of 3,500 cubic feet
capacity. The process is sure and quite economical, since sulphide of
carbon is sold at about five cents per pound, which amounts to 25 cents
for a room of 3,500 cubic feet capacity. The burner costs ten dollars,
but may be used for an almost indefinite period.

The process of producing sulphurous acid by the combustion of sulphide of
carbon is, as may be seen, very practical and advantageous. It does not
affect metallic objects, and it furnishes a disinfecting gas
continuously, slowly, and regularly.

Mr. Ckiandi's burner may also be applied in several industries. It is
capable of rendering great services in the bleaching of silk and woolen
goods, and it may also be used for bleaching sponges, straw hats, and a
number of other objects.--_La Nature_.

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THE DETERMINATION OF GRAPHITE IN MINERALS.

By J.B. MACKINTOSH.


In many instances the accurate determination of the amount of graphite
present in a rock has proved a rather troublesome problem. The first
thought which naturally suggests itself is to burn the graphite and weigh
the carbonic acid produced; but in the case of the sample which led me to
seek for another method, this way could not be employed, for the specimen
had been taken from the surface, and was covered and penetrated by
vegetable growths which could not be entirely removed mechanically. Add
to this the fact of the presence of iron pyrites and the probable
occurrence of carbonates in the rock, and it will be at once seen that no
reliance could be placed on the results obtained by this suggested
method.

As the problem thus resolved itself into finding a way by which all
interfering substances could be destroyed without affecting the graphite,
it at once occurred to me to try the effect of caustic potash. I melted a
few pieces of potash in a silver crucible until it had stopped spitting
and was in quiet fusion. I then transferred the weighed sample to the
crucible, the melted potash in which readily wetted the graphite rock.
The mass was then gently heated, and occasionally stirred with a piece of
silver wire. The heat never need be much above the melting point of the
potash, though toward the last I have been in the habit of raising the
temperature slightly, to insure the complete decomposition of the melt.
When the decomposition is complete, which can be known by the complete
absence of gritty particles, the crucible is cooled and then soaked out
in cold water. This is very quickly accomplished, and we then see that we
have an insoluble residue of graphite and a flocculent precipitate of
lime, magnesia, iron hydrate, etc., while the organic matters have
disappeared. The sulphides of iron, etc., have given up their sulphur to
the potash, and everything except the graphite has suffered some change.
The solution is now filtered through a weighed Gooch crucible, the
residue washed a few times with water, and then treated with dilute
hydrochloric acid (followed by ammonia to remove any silver taken up from
the crucible), which will dissolve all the constituents of the residue
except the graphite, and after washing will leave the latter free and in
a condition of great purity.

As evidence of the accuracy of the method, I subjoin the results I
obtained on a sample whose gangue was free from all organic and other
impurities, consisting chiefly of quartz:

New Method.       Combustion in Oxygen, Weighing CO_{2}.
  15.51                         15.54

It is plain that such a result leaves nothing to be desired for the
accuracy of the method, while, as regards time and trouble, the advantage
lies on the side of the new method. I have completed a determination in
less than two hours from the start, and did not hurry myself over it in
any degree.

Fine pulverization of the sample is not essential, and in fact is rather
detrimental, as the graphite, when fine, is more difficult to wash
without loss. When operating on a coarse sample more time is necessarily
taken, but the resulting graphite shows the manner of occurrence better,
whether in scales or in the amorphous form.

In consulting the literature bearing on the subject, I cannot find any
mention of this method employed as an analytical process; it has,
however, been previously described as a commercial method for the
purification of graphite,[1] and I understand has been tried on a small
scale in this country. The method, though inexpensive, yet seems to have
been abandoned for some reason, and I am not aware that it is now
employed anywhere.--_Sch. Mines Quarterly._

[Footnote 1: Schloffel, Zeitschrift der K.K. geolog. Reichanstalt, 1866,
p. 126.]

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SULPHOCYANIDE OF POTASSIUM.


The elements of cyanogen, combined with sulphur, form a salt radical,
sulphocyanogen, C_{2}NS_{2}, which is expressed by the symbol Csy. The
sulphocyanide of potassium, KCsy, is prepared by fusing ferrocyanide of
potassium, deprived of its water of crystallization, intimately mixed
with half its weight of sulphur and 17 parts of carbonate of potassa. The
molten mass, after having cooled, is exhausted with water, the solution
evaporated to dryness, and extracted with alcohol, from which the
crystals of the salt are separated by evaporation.

It is also made by melting the ferrocyanide of potassium with sulphide of
potassium. It is a white, crystallizable salt of a taste resembling that
of niter, soluble in water and alcohol, and extremely poisonous. It
dissolves the chlorides, iodides, and bromides of silver, is, therefore,
a fixing agent, but has not come in general use as such. Vogel speaks
highly of it as an addition to the positive toning bath, although he
prefers the analogous ammonium salt in the following formula:

Chloride of gold solution.... (1:50) 3 c. cm. (46-1/5 grains).
Sulphocyanide of ammonium ... 20 grammes (308 grains).
Water........100 c. cm. (3 ounces 5 drachms 40 grains).

_Ferrocyanide of Potassium_--K_{2}Cfy+3HO, or K_{2}C_{8}N_{3}Fe+3HO, is
generally known by the name of yellow prussiate of potassa. It contains
ferrocyanogen, a compound radical, consisting of 1 eq. of metallic iron
and 3 eq. of the elements of cyanogen, and is designated by the symbol
Cfy.

The potassium salt is manufactured on a large scale from refuse animal
matter, as old leather, chips of horn, woolen rags, hoofs, blood (hence
its German name, "Blutlaugen salz"), greaves, and other substances rich
in nitrogen, by fusing them with crude carbonate of potassa and iron
scraps or filings to a red heat, the operation to go on in an iron pot or
shell, with the exclusion of all air. Cyanide of potassium is generated
in large quantities. The melted mass is afterward treated with hot water,
which dissolves the cyanide and other salts, the cyanide being then
quickly converted by the action of oxide of iron, formed during the
operation of fusing, into ferrocyanide. The filtered solution is
evaporated, crystallized, and recrystallized. The best temperature for
making the solution is between 158 and 176 deg. F. The conversion of the
cyanide into the ferrocyanide is greatly facilitated by the presence of
finely divided sulphuret of iron and caustic potash. Some years ago this
salt was manufactured by a process which dispensed with the use of animal
matter, the necessary nitrogen being obtained by a current of atmospheric
air. Fragments of charcoal, impregnated with carbonate of potassa, were
exposed to a white heat in a clay cylinder, through which a current of
air was drawn by a suction pump. The process succeeded in a chemical
sense, but failed on the score of economy.

Richard Brunquell passes ammonia through tubes filled with charcoal, and
heated to redness so as to form cyanide of ammonium, which is converted
into the ferrocyanide of potassium by contact with potash solution and
suitable iron compounds. Ferrocyanide of potassium is in large beautiful
transparent four-sided tabular crystals, of a lemon-yellow color, soluble
in four parts of cold and two of boiling water, insoluble in alcohol.
Exposed to heat it loses three eq. of water, and becomes anhydrous; at a
high temperature it yields cyanide of potassium, carbide of iron, and
various gases. This salt is said to have no poisonous properties,
although the dangerous hydrocyanic acid is made from it. In large doses
it occasions, however, vertigo, numbness, and coldness. It is used in
various photographic processes. Newton employs it in combination with
pyrogallol and soda in the development of bromo-gelatine plates.

The ferri or ferrid cyanide of potassium discovered by Gmelin is often,
but improperly, termed red prussiate of potash. It is formed by passing a
current of chlorine gas through a solution of ferrocyanide of potassium
until the liquid ceases to give a precipitate with a salt of sesquioxide
of iron, and acquires a deep, reddish-green color. The solution is then
evaporated, crystallized, and recrystallized. It forms regular prismatic
or tabular crystals, of a beautiful ruby-red tint, permanent in the air,
soluble in four parts of cold water. The crystals burn when introduced
into the flame of a candle, and emit sparks.

The theory of the formation of this salt is, that one eq. of chlorine
withdraws from two eq. of the ferrocyanide of potassium, one eq. of
potassium, forming chloride of potassium, which remains in the mother
liquid. The reaction is explained by the following equation:
2(K_{2}Cfy)+Cl=K_{3}Cfy_{2}+KCl.

The radical ferridcyanogen, isomeric[2] with ferrocyanogen, is supposed
to be formed by the coalescence of two equivalents of ferrocyanogen, and
is represented by the symbol Cfdy; accordingly the formula of
ferridcyanide of potassium is K_{3}Cfdy.

[Footnote 2: Isomeric bodies, or substances different in properties yet
identical in composition, are of constant occurrence in organic
chemistry, and stand among its most peculiar features.]

Ferridcyanide of potassium has found extensive application in
photographic processes for intensifying negatives; those of Eder, in
combination with nitrate of lead, or Selle's, with nitrate of uranium;
Ander's blue intensification of gelatine negatives, Farmer's process of
reducing intensity, the coloring of diapositives, the very important blue
printing, and various others, are daily practiced in our laboratories.

The ferrocyanide of potassium is a chemical reagent of great value,
giving rise to precipitates with the neutral or slightly acid solutions
of metals, like the beautiful brown ferrocyanide of copper, and that of
lead. When a ferrocyanide is added to a solution of a sesquioxide of
iron, Prussian blue or ferrocyanide of iron is produced. The exact
composition of this remarkable substance is not distinctly stated, as
various blue compounds may be precipitated under different circumstances.
Berzelius gives the following account: 3 eq. of ferrocyanide and 2 eq. of
sesquioxide of iron are mutually decomposed, forming 1 eq. of Prussian
blue and 6 eq. of the potassa salt, which remains in solution, or
3K_{2}Cfy + 2(Fe_{2}O_{3}3NO_{3}) = Fe_{4}Cfy_{3} + 6(KO,NO_{5}). It
forms a bulky precipitate of an intense blue, is quite insoluble in water
or weak acids, with the exception of oxalic acid, with which it gives a
deep blue liquid, occasionally used as blue ink.

Ferridcyanide of potassium, added to a salt of the sesquioxide of iron,
yields no precipitate, but merely darkens the reddish-brown solution;
with protoxide of iron it gives a blue precipitate, containing
Fe_{3}Cfdy, which is of a brighter tint than that of Prussian blue, and
is known by the name of Turnbull's blue. Hence, the ferridcyanide of
potassium is as excellent a test for protoxide of iron as the yellow
ferrocyanide is for the sesquioxide.--_E., Photo. Times_.

       *       *       *       *       *




FOUCAULT'S APPARATUS FOR MANUFACTURING ILLUMINATING GAS AND
HYDROGEN.


The illuminating gas and hydrogen apparatus, illustrated herewith, is
adapted to all cases in which it is desirable to manufacture gas upon a
small scale.

Through the use solely of oil or water, it produces illuminating gas or
pure hydrogen for all the applications that may be required of them. It
consists of three parts, viz., of a vaporizer, A, which converts the
liquids into gas; of a distributer, B, which contains and distributes the
liquids to be converted into gas, and of a regulator, C, which
automatically regulates the flow of the liquids in proportion as they are
used.

[Illustration: FIG. 1.--FOUCAULT'S GAS APPARATUS.]

In the vaporizer Mr. Foucault, the inventor of the apparatus, obtains a
perfectly regular combustion through the use of a central column, 15,
charged with fuel, closed at the upper part, open beneath, and entering a
furnace that is fed by it with regularity, the zone of combustion not
being able to extend beyond the level of the draught. The grate, 16, is
capable of revolving upon its axis in order to separate the cinders. It
also oscillates, and is provided with jaws for crushing the fuel; and it
may likewise be lowered so as to let the fire drop into the ash-pan when
it is desired to stop operations.

The vaporizer, properly so called, is not placed directly over the fire,
and for this reason the production of a spheroidal state of the liquid is
avoided. It consists of a vessel, 44, into which the liquid is led by a
pipe, 43. The cast-iron evaporating vessel, 14, is provided with
appendages, 14 _bis_, which dip into the liquid and bring about its
evaporation. A refractory clay sleeve, 41, protects the lower part of the
cylinder, 15, from the fire, and diminishes the smoke passages at 42. The
vapor produced makes its way vertically through a layer of charcoal
placed between the evaporating vessel, 14, and the receiver, 17, and
serving to decompose the aqueous vapor formed.

All clay and red and white lead joints are done away with in this part of
the apparatus, as are also packing bolts. Thus, at the upper part the
cover, 19, is provided with a rim that enters a cavity filled with lead,
so, too, the lower part of the evaporating vessel, 14, rests in a channel
containing lead. There is also at 30, a joint of the same character for
the rim of the external cylindrical vessel, 18. Both this latter and the
receiver, 17, dip beneath into a tank of water, 66.

The distributer, B, is so arranged as to cause the water, and oil, and
the liquids to be vaporized to flow with the greatest regularity, and
proportionally to the consumption of the gas in cases where the latter is
not stored up in a gas meter. The flow is controlled by cocks that are
actuated by variations in the height of the regulator receiver. All the
condensation that occurs in the various parts of the apparatus collects
in a receptacle, 52, so arranged as to perform the office of a separator
and set apart the oil at 20, and the water at 21, through the natural
effect of their difference in density. This latter is likewise utilized
for causing the oil to flow into the vaporizer through 26 and 27, instead
of using a graduated cock that receives a variable pressure from the
receiver. In this way every cause of obstruction is avoided.

[Illustration: FIG. 2.--SECTION.]

We have stated that the regulator, C, serves to automatically regulate
the flow of the liquids proportionally to the consumption of the gases
produced. To effect this a communication is established between the
regulator receiver, 59, and the aperture through which the liquids flow,
and the flow is thus modified by the valves, 54 and 55.

The water contained in the reservoir of the regulator serves to wash the
gas which enters through a number of orifices in the disk, 60, this
latter being fixed beneath the level of the water. The gas may be
purified by dissolving metallic salts in the water.

By means of the arrangement above described, there may be manufactured at
will a rich gas from liquid hydrocarburets, hydrogen from water, and gas
obtained by an admixture of two others simultaneously produced and
combined in the apparatus.--_Chronique Industrielle._

       *       *       *       *       *




SUGAR NITRO-GLYCERINE.


A new explosive has been discovered by M. Roca, a French engineer, who
communicates an account of it to _Le Génie Civil_. The discovery was due
entirely to scientific induction from some experiments made upon
different specimens of dynamite, with a view to the determination of the
effect on the explosive force of the various inert or at least slowly
combustible substances with which nitro-glycerine is mixed to produce the
dynamite of commerce. Of late, in place of the infusorial earth which
formed the solid portion of Nobel's dynamite, such substances as sawdust,
powdered bark, and even gunpowder, have been used, probably for the sake
of economy alone, without, except in the latter case, any reference to
the influence which they might have upon the combustion of the
nitro-glycerine; but M. Roca, in testing a variety of samples, was struck
by the difference among them in regard to energy of explosion, and
discovered that if a portion of free carbon, sufficient to combine with
the oxygen disengaged from the nitro-glycerine, was present at the moment
of detonation, the effect was greater than where, as in the case of
gunpowder, the solid portion alone furnished oxygen enough to burn all
the free carbon, without calling upon the nitro-glycerine for any. In
fact, it appeared from experiment that the dose of carbon might with
advantage be so great as not only to be itself oxidized into carbonic
oxide by the oxygen of the nitro-glycerine, but to reduce the carbonic
acid developed by the explosion of the latter itself into carbonic oxide.
The limit of the advantageous effect of free carbon ceased here, and if
more were added to the mixture, the cavities formed by the explosion in
the lead cubes used for test were found simply lined with soot; but up to
the limit necessary for converting all the carbon in the dynamite into
carbonic oxide, the addition of a reducing agent was shown to be an
important gain. This was confirmed by theory, which shows that pure
nitro-glycerine, which is composed of six parts of carbon and two of
hydrogen, combined with three times as much nitric acid and water,
decomposes on explosion into six parts of carbonic acid, five of watery
vapor, one of oxygen, and three of nitrogen, while the addition of seven
more parts of free carbon to the mixture causes the development, by
explosion, of thirteen volumes of carbonic oxide, five parts of watery
vapor, and three of nitrogen, or twenty-one volumes of gas in place of
fifteen. As the power of an explosive depends principally on the amount
of gas which results from its sudden combustion, it was evident that the
addition of pure or nearly pure carbon, in a condition to be readily
combined with the other elements, ought to increase materially the force
of nitro-glycerine, and M. Roca experimented accordingly with an
admixture of sugar, as a highly carbonized body immediately available,
and found that three parts of this, mixed with seven parts of
nitro-glycerine, detonated with a force from thirty to thirty-five per
cent. greater than that of pure nitro-glycerine. Many other organic
carbonaceous substances may be employed in place of sugar, with various
advantages. In comparing these simple compounds with the celebrated
explosive gum, prepared by dissolving gun-cotton in nitro-glycerine, it
is found that the latter is far inferior, having an energy very little
superior to that of pure nitro-glycerine.

       *       *       *       *       *




THE CIRCLE-DIVIDER.


This little apparatus, invented by Prof. Mora, of Senlis, permits of
dividing circumferences or circles into equal or proportional parts. It
consists (Fig. 2) of a rule, A, divided into equal or proportional parts,
which pivots in the manner of a compass around a rod, T, that serves as a
central rotary point. Along this rule moves a slide, R, provided with an
aperture, C, which is made to coincide with one of the divisions. This
division corresponds to the number of equal or proportional parts into
which the circle is to be divided. The slide is provided with a wheel, E,
that carries a point which serves at every revolution to trace the points
that indicate the divisions of the circumference.

[Illustration: FIG. 1.--MODE OF USING THE CIRCLE DIVIDER. ]

The apparatus operates as follows: Suppose, for example, that it becomes
necessary to divide a circumference into 19 equal parts: We make the
aperture, C, coincide with the 19th division of the rule, and fix the
point of the rod, T, in the center of the circumference, and cause the
rule to revolve around it. The wheel, E, will revolve upon its axis, g,
and, at every revolution, its point will make a mark which corresponds to
the 19th part of the circumference--

Circumf. c / Circumf. C = r / R

It is always necessary that the extremity of the wheel, E, and the
center-point, T, shall be at the same height in order to have the
divisions very accurate.

[Illustration: FIG. 2.--THE CIRCLE DIVIDER. ]

       *       *       *       *       *




SOLUBLE GLASS.


Although the manufacture of soluble glass does not strictly belong to the
glass maker's art, yet it is an allied process to that of manufacturing
glass. Of late soluble glass has been used with good effect as a
preservative coating for stones, a fire-proofing solution for wood and
textile fabrics. Very thin gauze dipped in a solution of silicate of
potash diluted with water, and dried, burns without flame, blackens, and
carbonizes as if it were heated in a retort without contact of air. As a
fire-proofing material it would be excellent were it not that the
alkaline reaction of this glass very often changes the coloring matters
of paintings and textile fabrics. Since soluble glass always remains
somewhat deliquescent, even though the fabrics may have been thoroughly
dried, the moisture of the atmosphere is attracted, and the goods remain
damp. This is the reason why its use has been abandoned for preserving
theater decorations and wearing apparel. Another application of soluble
glass has been made by surgeons for forming a protecting coat of silicate
around broken limbs as a substitute for plaster, starch, or dextrine.

The only use where soluble glass has met with success is in the
preservation of porous stones, building materials, paintings in
distemper, and painting on glass. Before we describe these applications,
we will give the processes used in making soluble glass.

The following ingredients are heated in a reverberatory furnace until
fusion becomes quieted: 1,260 pounds white sand, 660 pounds potash of
78°. This will produce 1,690 pounds of transparent, homogeneous glass,
with a slight tinge of amber. This glass is but little soluble in hot
water. To dissolve it, the broken fragments are introduced into a iron
digester charged with a sufficient quantity of water, at a high pressure,
to make a solution marking 33° to 35° Baume. Distilled or rain water
should be used, as the calcareous salts contained in ordinary water would
produce insoluble salts of lime, which would render the solution turbid
and opalescent; this solution contains silica and potash combined
together in the proportion of 70 to 30.

Silicate of soda is made with 180 parts of sand, 100 parts carbonate of
soda (0.91), and is to be melted in the same manner as indicated
previously.

Soluble glass may also be prepared by the following method: A mixture of
sand with a solution of caustic potash or soda is introduced into an iron
boiler, under 5 or 6 atmospheres of pressure, and heated for a few hours.
The iron boiler contains an agitator, which is occasionally operated
during the melting. The liquid is allowed to cool until it reaches 212°,
and is drawn out after it has been allowed to clear by settling; it is
then concentrated until it reaches a density of 1.25, or it may be
evaporated to dryness in an iron kettle. The metal is not affected by
alkaline liquors.

The glass is soluble in boiling water; cold water dissolves but little of
it. The solution is decomposed by all acids, even by carbonic acid.
Soluble glass is apparently coagulated by the addition of an alkaline
salt; mixed with powdered matters upon which alkalies have no effect, it
becomes sticky and agglutinative, a sort of mineral glue.

To apply soluble glass for the preservation of buildings and monuments of
porous materials, take a solution of silicate of potash of 35° Baume,
dilute it with twice its weight of water, paint with a brush, or inject
with a pump; give several coats. Experience has shown that three coats
applied on three successive days are sufficient to preserve the materials
indefinitely, at a cost of about 15 cents per square yard. When applied
upon old materials, it is necessary to wash them thoroughly with water.
The degree of concentration of the solutions to be used varies with the
materials. For hard stones, such as sand and free stones, rock, etc., the
solution should mark 7° to 9° Baume; for soft stones with coarse grit, 5°
to 7°; for calcareous stones of soft texture, 6° to 7°. The last coating
should always be applied with a more dilute solution of 3° to 4° only.

Authorities are divided upon the successful results of the preservation
of stone by silicates. Some claim in the affirmative that the protection
is permanent, while others assert that with time and the humidity of the
atmosphere the beneficial effects gradually disappear. It might be worth
while to experiment upon some of the porous sandstones, which, under the
extreme influence of our climate, rapidly deteriorate; such, for
instance, as the Connecticut sandstone, so popular at one time as a
building material, but which is now generally discarded, owing to its
tendency to crumble to pieces when exposed to the weather even for a few
years.

Soluble glass has also been used in Germany to a great extent for mural
painting, known as stereochromy. The process consists in first laying a
ground with a lime water; when this is thoroughly dry, it is soaked with
a solution of silicate of soda. When this has completely solidified, the
upper coating is applied to the thickness of about one-sixteenth of an
inch, and should be put on very evenly. It is then rubbed with fine
sandstone to roughen the surface. When thoroughly dry, the colors are
applied with water; the wall is also frequently sprinkled with water. The
colors are now set by using a mixture of silicate of potash completely
saturated with silica, with a basic silicate of soda (a flint liquor with
soda base, obtained by melting 2 parts sand with 3 parts of carbonate of
soda). As the colors applied do not stand the action of the brush, the
soluble glass is projected against the wall by means of a spray. After a
few days the walls should be washed with alcohol to remove the dust and
alkali liberated.

The colors used for this style of painting are zinc white, green oxide
of chrome, cobalt green, chromate of lead, colcothar, ochers, and
ultramarine.

Soluble glass has also been used in the manufacture of soaps made with
palm and cocoanut oil; this body renders them more alkaline and harder.

Interesting experiments have been made with soluble glass for coloring
corals and shells. By plunging silicated shells into hot solutions of
salts of chrome, nickel, cobalt, or copper, beautiful dyes in yellow,
green, and blue are produced. Here seems to be a field for further
application of this discovery.

Soluble glass has also been applied to painting on glass in imitation of
glass staining. By using sulphate of baryta, ultramarine, oxide of
chrome, etc., mixed with silicate of potash, fast colors are obtained
similar to the semi-transparent colors of painted windows. By this means
a variety of cheap painted glass may be made. Should these colors be
fired in a furnace, enameled surfaces would be produced. As a substitute
for albumen for fixing colors in calico printing, soluble glass has been
used with a certain degree of success; also as a sizing for thread
previous to weaving textile fabrics. Thus it would seem that this
substance has been used for many purposes, but since its application does
not seem to have been extended to any great degree, the defects here
pointed out in its use as a fire-proofing material perhaps also exist, to
a certain degree, in its other applications. In painting upon glass, for
instance, it is asserted that the brilliancy and finish of ordinary
vitrified colors cannot be obtained.--_Glassware Reporter._

       *       *       *       *       *




THE JET VENTILATOR.


[Illustration: KORTING'S JET VENTILATOR.]

Messrs. Korting bros., of London, induced by the interest that has been
directed to the separate ventilation of mines in which fire-damp is apt
to form, have adopted for this purpose their jet ventilator. The
instrument, which we illustrate in Fig. 1, has been, we understand,
considerable simplified, and adapted for the special object in view. The
ventilators are worked by compressed air, and are so arranged that,
without stopping their action, the quantity of air they deliver can be
rapidly increased or diminished. This ample power of control has been
arranged for by the special wish of the mining authorities, who wish to
regulate the ventilation according to the development of fire-damp or the
greater or less number of men at work. Under circumstances of this kind
the quantity of air taken into the mine can be changed instantly. The
illustrations, Figs. 2, 3, and 4, show different modes of fixing the jet
ventilator. In Fig. 2, it is arranged to blow the air forward; in Fig. 3,
it is shown exhausting the air; and in Fig. 4, it is represented as
exhausting and blowing simultaneously, the efficiency in each case being
always the same. Any bends in the conduit affect the result to a very
slight degree, and the ventilator may be used with advantage when the
conduit is divided as in Fig. 4, in order to get the fresh air to
different points. The ventilators are easily fixed to the air conduits.
If they are to be connected to zinc air pipes, the pipe is simply slipped
over the point, L. in Fig. 1, and if to wooden conduits the apparatus is
simply put into them, and if no other support is required. Furthermore,
they are so light that it suffices for one man to fix them or change
their position.

Messrs. Korting Bros. advance the following claims for this mode of
ventilating mines: Certainty of action, no moving parts whatever,
and, consequently, no need of lubrication; no need of attention.
--_Mech. World_.


       *       *       *       *       *




ON REMELTING OF CAST IRON.


From trials conducted by Ledebur, it appears that cast iron is rendered
suitable for foundry purposes--i.e., to fill the moulds well and to yield
sharp and definite forms free of flaws, to be cut with a chisel, and
turned on a lathe--through a certain percentage of graphite, whose
presence depends on that of carbon and silicium. Cast iron free of
silicium yields on cooling the entire amount of carbon in the amorphous
state, while presence of the former metal gives rise to the formation of
graphite, and, consequently, causes a partial separation of carbon. Iron
suffers on casting loss of graphite, assumes a finely-grained texture,
becomes hard and brittle, and is changed from gray to white. In view of
the fact that samples of cast iron with equal percentage of silicium and
carbon yield on casting a different product, it has become necessary to
institute experiments as to the cause of this behavior. Samples of cast
iron were therefore repeatedly melted, and thin sections of each melt
examined; these sections exhibited a gray color, though less apparent
than in the unmelted sample, and possessed sufficient softness to admit
boring and filing. During these processes of fusing, the amount of
silicium, carbon, and manganese had been gradually decreased, and
amounted to 12.7, 17.6, and 24.4 per centum for silicium in the three
samples examined. It also was observed that the more manganese the iron
contains the less readily the percentage of silicium is diminished; and
since manganese is more subject to oxidation than silicium, it is capable
to reduce silicic acid of the slag or lining to metal, and thus to
augment the amount of silicium in cast iron. The percentage of carbon
also suffers diminution by oxidation, which latter process is impeded by
presence of manganese, a fact of some importance in melting of cast iron
in the cupola furnace. An excess of manganese renders cast iron hard and
brittle, and imparts to it the properties to absorb gases, while an
amount of 1.5 per centum, as found in Scotch iron, undoubtedly has the
effect to produce those properties for which this iron is held in high
repute. The amount of copper is not visibly altered by fusion, but that
of phosphorus and sulphur slowly increased.

Experiments in regard to the relation between chemical composition and
strength of the material have established that a large amount of
silicium, graphite, manganese, and combined carbon reduce the elasticity,
strength, and tenacity of cast iron, and that a limited percentage of
silicium counteracts the injurious influence produced by an excess of
combined carbon. On remelting of cast iron, increase in tensile strength
was observed, which attained its maximum in iron with a small percentage
of silicium after the third, and in such with a large amount after the
fourth melting. The increase in tensile strength was accompanied by a
loss of silicium, graphite, and manganese coupled with a simultaneous
augmentation of combined carbon. A fifth melting of the cast iron renders
it hard, brittle, and white, through oxidation of silicium and subsequent
lowering of the amount of carbon. On lessening the percentage of combined
carbon with formation of graphite the injurious influence of the
accessorial constituents of cast iron is diminished, especially that
produced by the presence of phosphorus.--_Eisenhuettentechnik._

       *       *       *       *       *




FEEDING BOILERS AT THE BOTTOM.


One of the most important things to be considered in boiler construction
is the position and arrangement of the feed apparatus, but it is,
unfortunately, one of the elements that is most often overlooked, or, if
considered at all, only in a very superficial manner. Many seem to think
that it is only necessary to have a hole somewhere in the boiler--no
matter what part--through which water may be pumped, and we have all that
is desired. This is a very grave error. Many boilers have been ruined,
and (we make the assertion with the confidence born of long experience) a
large number of destructive explosions have been directly caused by
introducing the feed water into boilers at the wrong point.

On the location and construction of the feed depends to some extent the
economical working of a boiler, and, to a great extent, especially with
certain types of boilers, its safety, durability, and freedom from a
variety of defects, such as leaky seams, fractured plates, and others of
a similar kind. And it is unfortunately true that the type of boiler
which from its nature is most severely affected by mal-construction, such
as we are now speaking of, is the very one which is the oftenest subject
to it. We are speaking now more particularly of the plain cylinder
boiler, of which there are many in use throughout the country.

Plain cylinder boilers are, as a rule, provided with mud drums located
near the back end. As a rule, also, these boilers are set in pairs over a
single furnace, and the mud drum extends across beneath, and is connected
to both, and one end projects through the setting wall at the side. Our
illustrations show a typical arrangement of this kind. Fig. 1 shows a
transverse section of the boilers and setting, while Fig. 2 shows a
longitudinal section of the same. It is a favorite method to connect the
feed pipe, F, to the end of the mud drum which projects through the wall,
and here the feed water is introduced, whether hot or cold; and there is
really not so much difference after all between the two, for no matter
_how_ effective a heater may be, the temperature to which it can raise
water passing through is quite low compared with the temperature of the
water in the boiler due to a steam pressure of say eighty pounds per
square inch. The difference in the effect produced by feeding hot or cold
water at the wrong place is one of degree, not of kind.

When a boiler is under steam of say eighty pounds per square inch, the
body of water in it will have a temperature of about 324 degrees Fahr.,
and the shell plates will necessarily be somewhat hotter, especially on
the bottom (just _how_ much hotter will depend entirely upon the quantity
of scale or sediment present). Now introduce a large volume of cold water
through an opening in the bottom, and what becomes of it? Does it rise at
once, and become mixed with the large body of water in the boiler? By no
means. It _cannot_ rise until it has become heated, for there is a great
difference between the specific gravity of water at 60°, or even 212°
Fahr., and water at 324°. Consequently, it "hugs" the bottom of the
boiler, and flows toward the _front_ end, or hottest portion of the
shell. Now let us examine the effect which it produces.

We know that wrought iron expands or contracts about 1 part in 150,000
for each degree that its temperature is raised or lowered. This is
equivalent to a stress of _one ton_ per square inch of section for every
15 degrees. That is, suppose we fix a piece of iron, a strip of
boilerplate, for instance, ¼ of an inch thick and 4 inches wide, at a
temperature of 92 degrees Fahr., between a pair of immovable clamps.
Then, if we reduce the temperature of the bar under experiment to that of
melting ice, we put a stress of four tons upon it, or one ton for each
inch of its width.

[Illustration: FIG. 1]

Now this is precisely what happens when cold water is fed into the bottom
of a boiler. We have the plates of the shell at a temperature of not
less, probably, than 350° Fahr. A large quantity of cold water, often at
a temperature as low as 50° Fahr., is introduced through an opening in
the bottom, and flows along over these heated plates. If it could produce
its _full_ effect at once, the contraction caused thereby would bring a
stress of 300 ÷ 15 = 20 tons per square inch upon the bottom plates of
the shell. But fortunately it cannot exert its full effect at once, but
it _can_ act to such an extent that we have known it to rupture the
plates of a new boiler through the seams on the bottom _no less than
three times in less than six weeks_ after the boilers were started up.

The effect in such cases will always be the most marked, especially if
the plant is furnished with a heater, when the engine is not running, for
then, as no steam is being drawn from the boilers, there is comparatively
little circulation going on in the water in the boiler, and the water
pumped in, colder than usual from the fact that the heater is not in
operation, spreads out in a thin layer on the lowest point of the shell,
and _stays there_, and keeps the temperature of the shell down, owing to
the fires being banked or the draught shut, while the larger body of
water above, at a temperature of from 300 to 325 degrees, keeps the upper
portion of the shell at _its_ higher temperature. It will readily be seen
that the strain brought upon the seams along the bottom is something
enormous, and we can understand why it is that many boilers of this class
rupture their girth seams while being filled up for the night after the
engine has been shut down. To most persons who have but a slight
knowledge of the matter, we fancy it would be a surprise to see the
persistence with which cold water will "hug" the bottom of a boiler under
such circumstances. We have seen boilers when the fire has been drawn,
and cold water pumped in to cool them off, so cold on the bottom that
they felt cold to the touch, and must consequently have had a temperature
considerably below 100° Fahr., while the water on top, above the tubes,
was sufficiently hot to scald; and they will remain in such a condition
for hours.

[Illustration: FIG. 2.]

The only thing to be done, where feed connections are made in the manner
described, is to change them, and by changing them at once much trouble,
or even a disastrous explosion, may be avoided. Put the feedpipe in
through the front head, at the point marked _p_ in Fig. 1, drill and tap
a hole the proper size for the feed pipe, cut a long thread on the end of
the pipe, and screw the pipe through the head, letting it project through
on the inside far enough to put on a coupling, then screw into the
coupling a piece of pipe not less than eight or ten feet long, letting it
run horizontally toward the back end of the boiler, the whole arrangement
being only from 3 to 4 inches below the water line of the boiler, and hot
or cold water may be fed indifferently, without fear of danger from
ruptured plates or leaky seams. In short, put in a "top feed," and avoid
further trouble.--_The Locomotive_.

       *       *       *       *       *




[MICROSCOPICAL JOURNAL.]

IRON PRINTING AND MICROSCOPIC PHOTOGRAPHY.

By C.M. VORCE, F.R.M.S.


I. FORMULAS FOR PRINTING SOLUTIONS.

_Blue Prints_.--The best formula for this process, of many that I have
tried, is that furnished by Prof. C.H. Kain, of Camden, N.J., in which
the quantity of ammonio-citrate of iron is exactly double that of the red
prussiate of potash, and the solutions strong. This gives strong prints
of a bright dark blue, and prints very quickly in clear sunlight.

Dissolve six grains of red prussiate of potash in one drm. of distilled
water; in another drm. of distilled water dissolve twelve grains of
ammonio-citrate of iron. Mix the two solutions in a cup or saucer, and at
once brush over the surface of clean strong paper. Cover the surface
thoroughly, but apply no more than the paper will take up at once; it
should become limp and moist, but not wet. The above quantity of
solution, two drms., will suffice to sensitize ten square feet of paper,
or three sheets of the "regular" size of plain paper, 18×22. As fast as
the sheets are washed over with the solution, hang them up to dry by one
corner. The surplus fluid will collect in a drop at the lower corner, and
can be blotted off.

_Black Prints_.--Wash the paper with a saturated solution of bichromate
of potash, made quite acid with acetic acid. After printing, wash the
prints in running water for twenty to thirty minutes, then float them
face down on a weak solution (five to ten per cent.) of protosulphate of
iron for five minutes, and wash as before. If preferred, the iron
solution may be washed over the prints, or they may be immersed in it,
but floating seems preferable. After the second washing, wash the prints
over with a strong solution of pyrogallic acid, when the print will
develop black, and the ground, if the washings were sufficient, will
remain white. A final washing completes the process.

If a solution of yellow prussiate of potash be used in place of the pyro
solution, a blue print is obtained. Bichromate prints can be made on
albumenized paper by floating it on the solution, and by using a
saturated solution of protosulphate of iron and a saturated solution of
gallic acid. Very fine prints can be so produced nearly equal to silver
prints, and at somewhat less cost, but with a little or no saving of time
or labor.

_Chief Proof Solution_.--If old oxalate developer be exposed in a shallow
vessel in a warm place, a deposit of light green crystals will be formed,
composed of an impure oxalate of iron. If these crystals be dissolved in
water, and paper washed with a strong solution, when dry it may be
exposed in the printing-frame, giving full time. The image is very faint,
but on washing in or floating on a moderately strong solution of red
prussiate of potash for a minute or less, a blue positive is produced,
which is washed in water as usual to fix it. The unused developer
produces the best crystals for the purpose, and the pure ammonio-oxalate
is vastly better than either.

All of the above operations, except the printing, should be carried on in
the dark room, or by lamp or gas light only. The solutions and the paper
should also be kept in the dark, and prepared as short a time as possible
before use.


II. COMPOUND NEGATIVES.

In photographing with the microscope, it frequently occurs that the
operator, instead of devoting a negative to each of two or more similar
objects for comparison, printing both upon the same print, prefers to
have the whole series upon one negative, and taking from this a single
print. There is often room for two or more images upon the same plate. If
the center of the plate is devoted to one, obviously no more can be
accommodated on it, but by placing one at each end, or one on each
quarter of the plate, both economy of plates and convenience of printing
are secured. The end may be readily accomplished by matting the plate as
a negative is matted in printing.

Suppose it be desired to photograph four different species of acari on
one plate, the image of each when magnified to the desired extent only
covering about one-fourth the exposed area of the plate. First, a mat is
prepared of card-board or thick non-actinic paper, which is adjusted to
exactly fill the opening of the plate holder, lying in front of and close
against the plate when exposed, and having one-quarter very exactly cut
out. A convenient way to fit this mat is to leave projecting lugs on each
side at exactly the same distance from the ends, and cut notches in the
plate-holder into which the lugs may closely fit. If this work is
carefully done, the mat may be reversed both sidewise and endwise, and
the lugs will fit the notches; if so, it is ready for use. The object
being focused upon the focusing glass or card, the camera is raised
one-half the vertical dimension of the plate and displaced to one side
half the horizontal dimension, when the image will be found to occupy
one-quarter of the plate. The mat being placed in the plate holder, a
focusing glass is inserted in the position the plate will occupy, and
final adjustment and focusing made. The plate is then marked on one
corner on the film side with a lead pencil, placed in the holder without
disturbing the mat, and the exposure made. When the plate is replaced for
a second exposure, either the mat is reversed or the plate turned end for
end; but it is best to always place the plate in the holder in the same
position and change the mat to expose successive quarters, but this
requires the camera to be moved for each exposure.

With similar objects, and some judgment in making two exposures,
negatives may be made with almost exactly the same density in each
quarter, and by cutting out slightly less than one-quarter of the mat the
four images will be separated by black lines in the print; by cutting out
a trifle more than the exact quarter, they will be separated by white
lines instead of black.

       *       *       *       *       *




PRACTICAL DIRECTIONS FOR MAKING LANTERN TRANSPARENCIES.

[Footnote: Abstract of a paper communicated to the Glasgow and West of
Scotland Amateur Photographic Association.--From the _Photographic
News_.]

By T.N. ARMSTRONG.


When the season for out-door work closes, amateurs begin to look about
for means of employment during the dark evenings. There is, fortunately,
no necessity for being idle, or to relinquish photographic pursuits
entirely, even though the weather and light combine to render out-door
work almost impracticable; and most amateurs will be found to have some
hobby or favorite amusement which enables them to keep in practice during
those months when many channels of employment are closed to them; and
probably one of the most popular as well as the most pleasing occupations
is the production of transparencies for the lantern.

It is not my desire to enter into any discussion as to this or that being
the best means of producing these delightful pictures, but merely to
describe a way by which a pleasant evening can be spent at photography,
and slides produced of much excellence by artificial light.

To-night I propose, by the aid of artificial light, to make a few slides
with Beechy's dry plates. On the whole, I have been most successful with
them, and have obtained results more satisfactory than by any of the
other processes I have tried. I do not say that results quite as good
cannot be obtained by any other method, for I know manipulative skill
plays a most important part in this class of work.

When I first took up the making of transparencies with wet collodion, I
was told that my sorrows would not be far to seek, and so I soon found
out. Need I tell you of all my failures, such as films floating off the
glass, oyster-shell markings, pin-holes, films splitting when dry, etc.,
etc., not to speak of going to business with fingers in fearful state
with nitrate of silver and iron developer? Now all these miseries have
gone, and I can, with dry collodion plates, work with the greatest of
comfort, and obtain results quite equal to the best products of any
method.

It may be interesting to some to know the formula by which the emulsion
is made, and as the making of it is by no means a difficult operation, I
may be pardoned if, before going fully into the more practical part of my
paper, I describe the formula, and also the manner in which I coat and
dry the plates. The formula is as follows, for which the world is
indebted to Canon Beechy:

In 8 ounces of absolute alcohol dissolve 5 drachms of anhydrous bromide
of cadmium. The solution will be milky. Let it stand at least twenty-four
hours, or until perfectly clear; it will deposit a white powder. Decant
carefully into an 8-ounce bottle, and add to it a drachm of strong
hydrochloric acid. Label this "bromide solution;" and it is well to add
on the label the constituents, which will be found to be nearly:

 Alcohol.              1 ounce.
 Bromide of cadmium.  32 grains.
 Hydrochloric acid.    8 drops.

This solution will keep for ever, and will be sufficient to last two or
three years, and with this at hand you will be able in two days to
prepare a batch of plates at any time. In doing so, you should proceed
thus: Make up your mind how many plates you mean to make, and take of the
above accordingly. For two dozen ½-plates or four dozen 3¼ by 3¼,
dissolve by heat over, but not too near, a spirit lamp, and by yellow
light, 40 grains of nitrate of silver in 1 ounce of alcohol 0.820. While
this is dissolving in a little Florence flask on a retort stand at a safe
distance from the lamp--which it will do in about 5 minutes--take of the
bromized solution ½ an ounce, of absolute ether 1 ounce, of gun-cotton
grains; put these in a clean bottle, shake once or twice, and the
gun-cotton, if good, will entirely dissolve. As soon as the silver is all
dissolved, and while quite hot, pour out the above bromized collodion
into a clean 4-ounce measure, having ready in it a clean slip of glass.
Pour into it the hot solution of silver in a continuous stream, stirring
rapidly all the while with a glass rod. The result will be a perfectly
smooth emulsion without lumps or deposit, containing, with sufficient
exactitude for all practical purposes, 8 grains of bromide, 16 grains of
nitrate of silver, and 2 drops of hydrochloric acid per ounce. Put this
in your stock solution bottle, and keep it in a dark place for
twenty-four hours. When first put in, it will be milky; when taken out,
it will be creamy; and it will be well to shake it once or twice in the
twenty-four hours.

At the end of this time you can make your two dozen plates in about an
hour. Proceed as follows: Have two porcelain dishes large enough to hold
four or six of your plates; into one put sufficient clean water to nearly
fill it, into the other put 30 ounces of clear, flat, _not acid,_ bitter
beer, in which you have dissolved 30 grains of pyrogallic acid. Pour this
through a filter into the dish, and avoid bubbles. If allowed to stand an
hour, any beer will be flat enough; if the beer be at all brisk, it will
be difficult to avoid small bubbles on the plate. At all events, let your
preservative stand while you filter your emulsion. This must be done
through perfectly clean cotton-wool into a perfectly clean collodion
bottle; give the emulsion a good shaking, and when all bubbles have
subsided, pour it into the funnel, and it will go through in five
minutes. The filtered emulsion will be found to be a soft, smooth, creamy
fluid, flowing easily and equally over the plates. Coat with it six
plates in succession, and place each, as you coat it, into the water. By
the time the sixth is in, the first will be ready to come out. Take it
out, see that all greasiness is gone, and place it in the preservative,
going on till all the plates are so treated.

A very handy way of drying is to have a flat tin box of the usual hot
plate description, which fill with hot water, then screw on the cap; on
this flat tin box place the plates to dry, which they will do rapidly;
when dry, store away in your plate box, and you will have a supply of
really excellent dry collodion plates.

Just a word as to the preparation of the glasses before coating. It is
very generally considered that it is better the glasses receive either a
substratum of albumen or very weak gelatine. I use the latter on account
of the great ease of its preparation. After your glasses are well
cleaned, place them in, and rub them with a weak solution of hydrochloric
acid of the strength of 2 ounces acid to 18 ounces water.

Prepare a solution of gelatine 1 grain to the ounce of water, rinse the
plate after removal from the acid mixtures, and coat twice with the above
gelatine substratum; the first coating is to remove the surplus water,
and should be rejected. Rear the plates up to drain, and dry in a plate
rack or against a wall, and be careful to prevent any dust adhering to
the surface while wet.

Having now described the plates I intend to use, let us next consider
what a transparency is, that we may understand the nature of the work we
are undertaking. You are all aware that if we take a negative, and in
contact with it place a sheet of sensitized paper, we obtain a positive
picture. Substitute for the paper a sensitive glass plate, and we obtain
also a positive picture, but, unlike the paper print, the collodion or
other plate will require to be developed to bring the image into view.
Now this is what is termed making a transparency by contact. It often
happens, however, that a lantern slide 3¼ by 3¼ has to embrace the whole
of a picture contained in a much larger negative, so that recourse must
be had to the camera, and the picture reduced with the aid of a short
focus lens to within the lantern size; this is what is called making a
transparency by reduction in the camera. Both cases are the same,
however, so far as the process being simply one of printing.

Those who have never made a transparency will have doubtless printed
silver prints from their negatives, and when printing, how often do you
find that to secure the best results you require to have recourse to some
little dodge.

Now, let us bear this in mind when using such a negative for the printing
of a transparency, for, as I have said before, it is only a process of
printing, after all. Although we cannot, when using a sensitive plate,
employ the same means of dodging as in the case of a silver print, still
we are not left without a means of obtaining the same results in a
different way, and this just brings me to what I have already hinted at
previously, that a deal more depends on the manipulative skill of the
operator than in the adoption of any particular make plate or formula;
and not only does this manipulative skill show itself in the exposure,
development, etc., but likewise comes into play in a marked manner even
in the preparation of the negative for transparency printing.

Let me deal with the latter point first. You will at once understand that
a negative whose size bears a proportion similar to 3¼ by 3¼ will lend
itself more easily to reduction; thus whole plate or half plate negatives
are easy of manipulation in this respect, and require but little doing
up. But as other sizes have at times to be copied into a disk¼ by 3¼,
recourse must be had to a sort of squaring of the negative. Now, here I
have a negative 7¼ by 4½, which is perhaps the worst of all sizes to
compress into the lantern shape, so I have, as it were, to square this
negative, and this I do by simply adding to sky. I take a piece of
card-board and gum it on to the glass side of the negative, and this
addition gives me a size that lends itself easily to reduction to the
lantern disk, and in no way detracts from the picture.

Having said so much about making up the size, let me add a few words as
to other preparations that are sometimes necessary. In a good lantern
transparency, it is, of all things, indispensable that the high lights be
represented by pure glass, absolutely clean in the sense of its being
free from any fog or deposit, to even the slightest degree; it is also
necessary that it be free from everything of heaviness of smudginess in
the details. To obtain these results, I generally have recourse to the
strengthening of the high lights of my negatives, and this I do with a
camel's hair brush and India ink, working on the glass side.

I nearly always block out my skies, and so strengthen the other parts of
my negatives, that I can rely on a full exposure without fear of
heaviness or smudginess. This blocking out is easily done.

Haying said so much about the preparation of the negative, let me now
describe the apparatus I use. I have here an ordinary flat board, and
here my usual camera; it is the one I use both for outside and inside
work. It is a whole-plate one, very strongly made, and has a draw of
twenty-three inches when fully extended; but this is not an unusual
feature, as nearly all modern cameras have their draw made as long as
this one. The lens I use is a Ross rapid symmetrical on five inches
focus, and here I have a broken-down printing frame with the springs
taken off, and here a sheet of ground glass. This is all that is
required. I mention this because I find it generally believed that a
special camera is required for this work, such as to exclude all light
between the negative and the lens; in my practice I have found this
unnecessary. There is nothing to hinder the use of ordinary cameras,
provided the draw is long enough, and the lens a short focus one.

Now let me describe how to go to work. I take the negative and place it
in the printing-frame, holding it in its place with a couple of tacks,
film-side next the lens, just as in printing; then stand the printing
frame on its edge on the flat board, and place the ground glass in front
of it--when I say in front of it, I mean not between the negative and
lens, but between the light and the negative. The ground glass can
conveniently be placed in another printing frame, and both placed up
against each other. I then bring my camera into play, and so adjust the
draw and distance from the negative, till I get the picture within the
disk on my ground glass. I find the best way is to gum a transparency
mask on the inside of the ground glass; this permits of the picture being
more easily brought within the required register. This done, focus
sharply, cap the lens, and then proceed to make the exposure.

Now, what shall I say regarding exposure? Just let us bear in mind again
that it is merely a printing process we are following up, as you will all
know that in printing no two negatives are alike in the time they
require. So in this case no two negatives are the same in their required
exposure. Still, with the plates I am going to use, so wide is their
range for exposure that but few failures will be made on this score,
provided we are on the safe side, and expose fully.

Although these plates are not nearly so fast as gelatine plates, it may
surprise you to be told that working with a negative which to daylight at
this dull time of the year required an exposure of sixteen minutes, will,
I hope, give me good results in about a tenth of this time; and this I
obtain by burning magnesium ribbon.

At first the error I fell into when using magnesium ribbon was too much
concentration of light. I now never allow the ribbon, when burning, to
remain in one position, but keep it moving from side to side, and up and
down, in front of the ground glass while making my exposure; and if there
be any dense place in the negative which, as in printing, would have
required printing specially up, I allow the light to act more strongly on
that part; the result, as a rule, being an evenly and well exposed plate.

I must not forget to explain to you the manner in which I coil up the
ribbon before I set it alight. I take an ordinary lead pencil, and wind
the ribbon round and round, thus making a sort of spiral spring; this
done, I gently pull the coils asunder. I then grasp the end of the ribbon
with a pair of pincers, light the other end, and make my exposure.

Having said so much regarding exposure, I shall now proceed to deal with
development. You will see me use a canary light, with which I can easily
see to read a newspaper. It may cause some of you surprise to see me use
so much light. It is the same lamp that I use for developing all my rapid
bromide plates; it is the best lamp I ever used. The canary medium is
inserted between the two sheets of glass 7¼ by 4½, the two glasses are
then fastened on to the tin with gummed paper, a few holes are bored in
the back for air, a funnel let in, and the thing is complete.

The formula for development is as follows:

Pyro.                96 grains.
Methylated spirits.   1 ounce.
Bromide of potash.   12 grams.
Water.                1 ounce.
Carbonate ammonia.   60 grains.
Water.                1 ounce.

Mix 30 drops pyro with from 30 to 60 drops bromide, then add 2 drachms
ammonia solution and 2 drachms of water.

I find a thin negative requires a slow development, and so gain contrast;
while hard negatives are best over-exposed and quickly developed.

The plate is first placed in water or rinsed under a gentle stream from
the tap till all greasiness has disappeared, it is then placed in a flat
dish, and the developer applied. Should it be found that some parts of
the picture are denser printed than should be by the ribbon acting more
strongly on some particular part--this is often the case if the negative
has been thinner in some parts than others, through uneven coating of the
plate--the picture need not be discarded as a failure, for I will explain
to you later on how to overcome this difficulty.

Fix the plate in hypo--the fixing takes place very quickly--then examine
the picture for the faults above described; if they are found, wash the
plate under the tap gently, and bring into operation a camel's hair brush
and a weak solution of cyanide of potassium. Apply the brush to the
over-printed parts, taking care not to work on the places that are not
too dense. Do not be afraid to use plenty of washing while this is being
done; let it be, as it were, a touch of the brush and then a dash of
water, and you will soon reduce the over-printed parts. It only requires
a little care in applying the brush.

After this wash well, and should it be deemed necessary to tone to a
black tone, use a weak solution of bichloride of platinum and chloride of
gold, or a very weak solution of iridium, in equal quantities, allowing
the picture to lie in the solution till the color has changed right
through to the back of the glass. Should a warm pinkish tone be desired,
I tone with weak solutions of ferri cyanide of potassium, nitrate of
uranium, and chloride of gold in about equal quantities.

After toning, wash well and dry; they dry quickly. Varnish with Soehnee
crystal varnish, then mount with covering glasses, and mark. Bind round
the edges with paper and very stiff gum, and the picture is complete.

The making of a really good transparency is by no means an easy or
pleasant task with a wet collodion plate, but with these dry plates an
amateur can, with a little practice, produce comfortably slides quite
equal to those procurable from professional makers.

       *       *       *       *       *




THE HONIGMANN FIRELESS ENGINE.


The invention of a self propelling engine, capable of working without
fuel economically and for a considerable time, has often been attempted,
and was, perhaps, never before so nearly accomplished as about the time
of the introduction into practical use of Faure's electric storage
batteries; but at the present moment it appears that electric power has
to give way once more to steam power. Mr. Honigmann's invention of the
fireless working of steam engines by means of a solution of hydrate of
soda--NaO HO--in water is not quite two years old, and has in that time
progressed so steadily towards practical success that it is reasonable to
expect its application before long in many cases of locomotion where the
chimney is felt to be a nuisance. The invention is based upon the
discovery that solutions of caustic soda or potash and other solutions in
water, which have high boiling points, liberate heat while absorbing
steam, which heat can be utilized for the production of fresh steam. This
is eminently the case with solutions of caustic soda, which completely
absorb steam until the boiling point is nearly reached, which corresponds
to the degree of dilution. If, therefore, a steam boiler is surrounded by
a vessel containing a solution of hydrate of soda, having a high boiling
point, and if the steam, after having done the work of propelling the
pistons of an engine, is conducted with a reduced pressure and a reduced
temperature into the solution, the latter, absorbing the steam, is
diluted with simultaneous development of heat, which produces fresh steam
in the boiler. This process will be made clearer by referring to the
following table of the boiling points of soda solutions of different
degrees of concentration, and by the description of an experiment
conducted by Professor Riedler with a double cylinder engine and tubular
boiler as shown in Fig. 2:

+---------------------+------------------+----------------------
|                     | Boiling point in | Steam pressure above
|  Solution of soda.  |   Centigrades.   | atmospheric pressure
|                     |                  |   in atmospheres.
+---------------------+------------------+----------------------
|100 NaO HO +  10 H2O | 256   deg. C.    |     40    atm.
|      "    +  20  "  | 220.5    "       |     21     "
|      "    +  30  "  | 200      "       |     15     "
|      "    +  40  "  | 185.5    "       |     10.2   "
|      "    +  50  "  | 174.5    "       |      7.7   "
|      "    +  60  "  | 166      "       |      6.1   "
|      "    +  70  "  | 159.5    "       |      5.1   "
|      "    +  80  "  | 154      "       |      4.2   "
|      "    +  90  "  | 149      "       |      3.6   "
|      "    + 100  "  | 144      "       |      3.0   "
|      "    + 120  "  | 136      "       |      2.2   "
|      "    + 140  "  | 130      "       |      1.6   "
|      "    + 200  "  | 120      "       |      0.95  "
|      "    + 300  "  | 110.3    "       |      0.4   "
|      "    + 400  "  | 107      "       |      0.3   "
+---------------------+------------------+----------------------

_Experiment No. 15_.[3]--The boiler of the engine, Fig. 2, was filled
with 231 kilogs. water of two atmospheres pressure and a temperature of
about 135 deg. Cent.; the soda vessel with 544 kilogs. of soda lye of
22.9 per cent. water and a temperature of 200 deg. Cent., its boiling
point being about 218 deg. Cent. The engine overcame the frictional
resistance produced by a brake. At starting the temperature of both
liquids had become nearly equal, viz., about 153 deg. Cent. The
temperature of the soda lye could therefore be raised by 47 deg. Cent,
before boiling took place, but, as dilution, consequent upon absorption
of steam would take place, a boiling point could only be reached less
than 218 deg. Cent., but more than 153 deg. Cent. The engine was then set
in motion at 100 revolutions per minute. The steam passing through the
engine reached the soda vessel with a temperature of 100 deg. Cent.; the
temperature of the soda lye began to rise almost immediately, but at the
same time the steam boiler losing steam above, and not being influenced
as quickly by the increased heat below, showed a decrease of temperature.
The difference of the two temperatures, which was at starting 1.3 deg.
Cent., consequently increased to 7.2 deg. Cent, after 17 min., the boiler
having then its lowest temperature of 148.8 deg. Cent. After that both
temperatures rose together, the difference between them increasing
slightly to 9.5 deg. Cent., and then decreasing continually. After 2 hours
13 min., when the engine had made 12,000 revolutions, the soda solution
had reached a temperature of 170.3 deg. Cent., which proved to be its
boiling point. The steam from the engine was now blown off into the open
air during the next 24 min. This lowered the temperature of both water
and soda lye by 10 deg. and re-established its absorbing capacity. The
steam produced under these circumstances had of course a smaller pressure
than before, in this way the engine could be driven at reduced steam
pressures until the resistance became relatively too great. The process
described above is illustrated by the diagram Fig. 1, which is drawn
according to the observations during the experiment.

[Footnote 3: Zeitschrift d. Vereins Deutscher Ingenieur, 1883, p. 730;
1884, p. 69.]

[Illustration: FIG. 1.]

[Illustration: FIG. 2.]

The constant rise of both temperatures during the first two hours, which
is an undesirable feature of this experiment, was caused by the quantity
of soda lye being too great in proportion to that of water, and other
experiments have shown that it is also caused by an increased resistance
of the engine, and consequent greater consumption of steam. In the latter
part of the experiment, where the engine worked with expansion, the rise
of the temperature was much less, and by its judicious application,
together with a proper proportion between the quantities of the two
liquids in the engines, which are now in practical use, the rising of the
temperatures has been avoided. The smaller the difference is between the
temperatures of the soda lye and the water the more favorable is the
economical working of the process. It can be attained by an increase of
the heating surface as well as by a sparing consumption of steam,
together with an ample quantity of soda lye, especially if the steam is
made dry by superheating. In the diagrams Figs. 3 and 4, taken from a
passenger engine which does regular service on the railway between
Wurselen and Stolberg, the difference of the two temperatures is
generally less than. 10 deg. Cent. These diagrams contain the
temperatures during the four journeys _a b c d_, which are performed with
only one quantity of soda lye during about twelve hours, and show the
effects of the changing resistances of the engine and of the duration of
the process upon the steam pressure, which, considering the condition of
the gradients, are generally not greater than in an ordinary locomotive
engine. It can especially be seen from these diagrams that an increase of
the resistance is immediately and automatically followed by an increased
production of steam. This is an important advantage of the soda engine
over the coal-burning engine, in consequence of which less skill is
required for the regular production of steam power. The tramway engines
of more recent construction according to Honigmann's system--Figs. 5 and
6--are worked with a closed soda vessel in which a pressure of 1/2 to 1½
atmospheres is gradually developed during the process. While the counter
pressure thus produced offers only a slight disadvantage, being at an
average only 1/2 atmosphere, the absorbing power of the soda lye is
materially increased, as shown by the following table, and it is,
therefore, possible to work with higher pressures than with an open soda
vessel. Besides this great advantage, it is also of importance that the
pressure in the steam boiler can be kept at a more uniform height.

[Illustration: FIG. 3.]

[Illustration: FIG. 4.]

TABLE.--100_kilogs. Soda Lye containing 20 parts Water with a
corresponding boiling point of 220 deg. Cent. absorb Steam as follows_:

+----------------------------------+--------------+---------------+
|Final pressure in condenser.      |              |               |
+----------------------------------+Pressure in   |Corresponding  |
|  0    | ½ atm. | 1 atm. | 1½ atm.|steam boiler. | temperature.  |
+----------------------------------+--------------+---------------+
|80 kil.|125 kil.|200 kil.|350 kil.|  2 atm.      | 136.0 deg. C. |
|65  "  | 88  "  |130  "  |190  "  |  3  "        | 143.0   "     |
|51  "  | 70  "  | 98  "  |125  "  |  4  "        | 153.3   "     |
|41  "  | 58  "  | 80  "  |100  "  |  5  "        | 160.0   "     |
|34  "  | 48  "  | 66  "  | 80  "  |  6  "        | 166.5   "     |
|27  "  | 40  "  | 55  "  | 70  "  |  7  "        | 172.1   "     |
|22½ "  | 33  "  | 47  "  | 60  "  |  8  "        | 177.4   "     |
|19  "  | 28  "  | 41  "  | 52  "  |  9  "        | 182.0   "     |
|16  "  | 24  "  | 35  "  | 46  "  | 10  "        | 186.0   "     |
|12  "  | 18  "  | 28  "  | 35  "  | 12  "        | 193.7   "     |
| 9  "  | 14  "  | 22  "  | 33  "  | 15  "        | 200.0   "     |
| 2  "  |  8  "  | 12  "  | 21  "  | 20  "        | 215.0   "     |
+-------+--------+--------+--------+--------------+---------------+

Not the least important part of the process with regard to its economy is
the boiling down of the soda lye in order to bring it back to the degree
of concentration which is required at the beginning of the process. This
is done in fixed boilers at a station from which the engines start on
their daily service, and to which they return for the purpose of being
refilled with concentrated soda lye. It is clear that a closed soda
vessel has produced as much steam when the process is over as it has
absorbed, and the quantity of coal required for the evaporation of water
in concentrating the soda lye can therefore be directly compared with
that required in an ordinary engine for the production of an equal
quantity of steam. The boiling down of the soda lye requires, according
to its degree of concentration, more coal than the evaporation of water
does under equal circumstances, and disregarding certain advantages which
the new engine offers in the economy of the use of steam, a greater
consumption of coal must be expected. But even at the small installation
for the Aix la Chapelle-Burtscheid tramway with only two boilers of four
square meters heating surface each, made of cast iron 20 mm. thick, 1
kilog. of coal converts 6 kilogs. of water contained in the soda lye into
steam, while in an ordinary locomotive engine of most modern construction
the effect produced is not greater than 1 in 10. There can be no doubt
that better results could be obtained if the installation were larger,
the construction of the boilers more scientific, and their material
copper instead of cast iron; but even without such improvements the cost
of boiling down the soda lye might be greatly lessened by the use of
cheaper fuel than that which is used in locomotive engines, and by the
saving in stokers' wages, since stokers would not be required to
accompany the engines.

[Illustration: FIG. 5]

[Illustration: FIG. 6]

Apart from these considerations, the Honigmann engines have the great
advantage that neither smoke nor steam is ejected from them, and that
they work noiselessly. The cost of the caustic soda does not form an
important item in the economy of the process, as no decrease of the
original quantities had been ascertained after a service of four months
duration. Besides the passenger engine already referred to, which was
tested by Herr Heusinger von Waldegg[4] in March, 1884, and which since
then does regular service on the Stolberg-Wurselen Railway, there are on
the Aix la Chapelle-Julich railway two engines of 45,000 kilogs. weight
in regular use, which are intended for the service on the St. Gothard
Railway. Their construction is illustrated in Figs. 7 and 9, and other
data are given in a report by the chief engineer of the Aix la
Chapelle-Julich Railway, Herr Pulzner, which runs as follows:

Wurselen, Dec. 23, 1884.

[Footnote 4: Z.d.V.D.I., 1884, p. 978]

[Illustration: DIAGRAMS FOR THE CALCULATION OF STRESSES IN BOWSTRING
GIRDERS.]

A trial trip was arranged on the line Haaren-Wurselen, the hardest
section of the Aix la Chapelle-Julich Railway. This section has a
gradient of 1 in 65 on a length of 4 kilos; and two curves of 250 and 300
meters radius and 667 meters length. The goods train consisted of
twenty-two goods wagons, sixteen of which were empty and six loaded. The
total weight of the wagons was 191,720 kilogs., and this train was drawn
by the soda engine with ease and within the regulation time, while the
steam pressure was almost constant, viz., five atmospheres. The greatest
load admissible for the coal burning engines of 45,000 kilogs. weight on
the same section is 180,000 kilogs.

[Illustration: FIG. 7.]

[Illustration: FIG. 8.]

Proof is therefore given that the soda engine has a working capacity
which is at least equal to that of the coal burning engine. The heating
surface of the soda engine, moreover, is 85 square meters, while that of
the corresponding new Henschel engine is 92 square meters. On a former
occasion I have already stated that the soda engine is capable not only
of performing powerful work and of producing a large quantity of steam
during a short time, but also of travelling long distances with the same
quantity of soda. Thus, for example, a regular passenger train, with
military transport of ten carriages, was conveyed on Nov. 6, 1884, from
Aix la Chapelle to Julich and back, i.e., a distance of 45 kilos, by
means of the fireless engine. The gradients on this line are 1 in 100, 1
in 80, and 1 in 65, being a total elevation of about 200 meters. For a
performance like this a powerful engine is required, and a proof of it can
be recognized in the consumption of steam during the journey, for the
quantity of water evaporated and absorbed by 4½ to 5 cubic meters soda
lye was 6,500 liters.

Another certificate concerning the tramway engine illustrated in Figs. 5
and 6 is of equal interest, and runs as follows:

Aix la Chapelle, Jan. 5, 1885.

A fireless soda engine, together with evaporating apparatus, has been at
work on the Aix la Chapelle-Burtscheid tramway for the last half year. In
order to test the working capacity of this locomotive engine, and the
consumption of fuel on a certain day, the Honigmann locomotive engine was
put to work this day from 8:45 o'clock a.m. till 8 o'clock p.m., with a
pause of three-quarters of an hour for the second quantity of soda lye.
The engine was, therefore, at work for fully 10½ hours, _viz._, 5½ hours,
with the first quantity, and five with the second. The distance between
Heinrichsalle and Wilhelmstrasse, where the engine performed the regular
service, is 1 kilo, and there are gradients

Of about 1 in 30 in 400 meter length.
   "     1  " 45  " 250    "
   "     1  " 72  " 350    "

This distance was traversed sixty-four times, the total distance,
including the journeys to the station, being 66 kilos. The engine gives
off fully 15-horse power on the steepest gradient, the total traction
weight being 8½ to 9 tons; it is worked with an average steam pressure of
5 atmospheres, and has cylinders of 180 mm. diameter and 220 mm. stroke,
cog wheel-gear of 2 to 3, and driving wheels of 700 mm. diameter. The
quantity of water evaporated during the service time of 10½ hours was
found to be about 1,600 kilogs., consequently about 800 kilogs. steam was
absorbed by one quantity of soda, the weight of which was ascertained at
about 1,100 kilogs. The averaging heating surface is 9.8 square meters;
the difference of temperature between soda lye and water was toward the
end only 3 deg. Cent.; 234 kilogs. pitcoal were used for boiling down the
lye for the 10½ hours' service, which corresponds to a 6.6 fold
evaporation.

(Signed) M.F. GUTERMUTH,

Assistant for Engineering at the Technical High School.

HASELMANN,

Manager of the Aix la Chapelle-Burtscheid Tramway.

Here are some unquestionable results. For nearly a year the first railway
engine, and for six months the first tramway engine of this new
construction, have been introduced into regular public service, and been
open to public inspection as well as to the criticism of the scientific
world. They are worked with greater ease and simplicity than ordinary
locomotive engines; the economy of their working appears, allowing for
shortcomings unavoidably attached to small establishments, to be at least
equally great: they do not emit either steam or smoke, and their action
is as noiseless as that of stationary engines.

In view of these facts it might be expected that railway managers, who
are continually told that the smoke of their engines is a serious
annoyance to the public, would be eager to make themselves acquainted
with them; it might, in particular, be expected that the managers of the
underground and suburban railways of this metropolis would lose no time
in making experiments on their own lines--if only by converting some of
their old engines into those of the fireless system--and assist a little
in the development of an invention, in the success of which they have a
tangible interest which is much greater than that of any railway on the
Continent, but there is no sign yet of their having done anything.--_E.,
in The Engineer_.

       *       *       *       *       *



SIMPLE METHODS OF CALCULATING STRESSES IN GIRDERS.

By CHARLES LEAN, M. Inst. C.E.


_Bowstring Girders._--Having had occasion to get out the stresses in
girders of the bowstring form, the author was not satisfied with the
common formulæ for the diagonal braces, which, owing to the difficulty of
apportioning the stresses amongst five members meeting in one point, were
to a large extent based on an assumption as to the course taken by the
stresses. As far as he could ascertain it, the ordinary method was to
assume that one set of diagonals, or those inclined, say, to the
right-hand, acted at one time, and those inclined in the opposite
direction at another time, and, in making the calculations, the
apportionment of the stresses was effected by omitting one set.
Calculations made in this way give results which would justify the common
method adopted in the construction of bowstring girders, viz., of bracing
the verticals and leaving the diagonal unbraced; but an inspection of
many existing examples of these bridges during the passing of the live
load showed that there was something defective in them. The long unbraced
ties vibrated considerably, and evidently got slack during a part of the
time that the live load was passing over the bridge. In order to get some
definite formulæ for these girders free from any assumed conditions as to
the course taken by the stresses, or their apportionment amongst the
several members meeting at each joint, the author adopted the following
method, which, he believes, has not hitherto been used by engineers:

Let Fig. 1 represent a bowstring girder, the stresses in which it is
desired to ascertain under the loads shown on it by the circles, the
figures in the small circles representing the dead load per bay, and that
in the large circle the total of live and dead load per bay of the main
girders. A girder, Fig. 1A, with parallel flanges, verticals, and
diagonals, and depth equal to the length of one bay, was drawn with the
same loading as the bowstring. The stresses in the flanges were taken
out, as shown in the figure, keeping separate those caused by diagonals
inclined to the left from those caused by diagonals inclined to the
right. The vertical component of the stress in the end bay of the top
flange of the bowstring girder, Fig. 1, was, of course, equal to the
pressure on the abutment, and the stress in the first bay of the bottom
flange and the horizontal component of the stress in the first bay of the
top flange was obtained by multiplying this pressure by the length of the
bay and dividing by the length of the first vertical. The horizontal
component of the stress in any other bay of the top or bottom flange of
the bowstring girder--Fig. 1--was found by adding together the product of
the stress in the parallel flanged girder, caused by diagonals inclining
to the right, divided by the depth of the bowstring girder at the left of
the bay, and multiplied by the depth of the parallel flanged girder; and
the product of the stress caused by diagonals inclining to the left
divided by the depth of the bowstring girder at the right of the bay,
multiplied by the depth of the parallel flanged girder. Thus the
horizontal component of the stress in D=
 _                                                                _
| Stress caused by diagonals   Length of right   Depth of parallel |
|      leaning to left.           vertical.       flanged girder.  |
|                                                                  | +
|_           15.75            ×       1/4.5     ×        10       _|
 _                                                                _
| Stress caused by diagonals   Length of ver-    Depth of parallel |
|     leaning to right.        tical to left.     flanged girder.  |
|                                                                  |
|_           24               ×       1/8       ×        10       _|

= 65; and the vertical component =

   Horizontal component.     Length of bay.

          65               ×       1/10   × (8.0 - 4.5) = 22.75.

In the same way the horizontal and vertical components of the stresses in
each of the other bays of the flanges of the bowstring were found; and
the stresses in the verticals and diagonals were found by addition,
subtraction, and reduction. These calculations are shown on the table,
Fig 1B. The result of this is a complete set of stresses in all the
members of the bowstring girder--see Fig. 2--which produce a state of
equilibrium at each point. The fact that this state of equilibrium is
produced proves conclusively that the rule above described and thus
applied, although possibly it may be considered empirical, results in the
correct solution of the question, and that the stresses shown are
actually those which the girder would have to sustain under the given
position of the live load. Figs. 2 to 10 inclusive show stresses arrived
at in this manner for every position of the live load. An inspection of
these diagrams shows: a. That there is no single instance of compression
in a vertical member of the bowstring girder, b. That every one of the
diagonals is subjected to compression at some point or other in the
passage of the live load over the bridge, c. That the maximum horizontal
component of the stresses in each of the diagonals is a constant
quantity, not only for tension and compression, but for all the
diagonals. The diagrams also show the following facts, which are,
however, recognized in the common formulæ: d. The maximum stress in any
vertical is equal to the sum of the amounts of the live and dead loads
per bay of the girder. e. The maximum horizontal component of the
stresses in any bay of the top flange is the same for each bay, and is
equal to the maximum stress in the bottom flange. Having taken out the
stresses in several forms of bowstring girders, differing from each other
in the proportion of depth to span, the number of bays in the girder, and
the amounts and ratios of the live and dead loads, similar results were
invariably found, and a consideration of the various sets of calculations
resulted in the following empirical rule for the stresses in the
diagonals: "The horizontal component of the greatest stress in any
diagonal, which will be both compressive and tensile, and is the same for
every diagonal brace in the girder, is equal to the amount of the live
load per bay multiplied by the span of the girder, and divided by sixteen
times the depth of girder at center." The following formulæ will give all
the stresses in the bowstring girder, without the necessity of any
diagrams, or basing any calculations on the assumed action of any of the
members of the girders:

Let S = span of girder.
    D = depth at center.
    B = length of one bay.
    N = number of bays.
    L = length of any bay of top flange.
    l = length of any diagonal.
    w = dead load per bay of girder.
    w¹= live load per bay of girder.
    W = total load per bay of girder = w + w¹.

Then: S/B = N.

Bottom Flange. WNS/8D = maximum stress throughout.    (1)

Top Flange.--In any bay the maximum stress =

+ WNS/8D × L/B = + WLN²/8D                            (2)

_Verticals._--The maximum stress = -W.                (3)

_Diagonals._--The maximum stress is

± w¹lS/16DB = ± w¹lN/16D                              (4)

These results show that the method generally adopted in the construction
of bowstring girders is erroneous; and one consequence of the method is
the observed looseness and rattling of the long embraced ties referred to
at the commencement of the article during the passage of the live load;
the fact being that they have at such times to sustain a compressive
stress, which slightly buckles them, and sets them vibrating when they
recover their original position.

Another necessity of the common method of construction is the use of an
unnecessary quantity of metal in the diagonals; for, by leaving them
unbraced, the set of diagonals which does act is subjected to exactly
twice the stress which would be caused in it if the bridge was properly
constructed. A comparison of the results of a set of calculations on the
common plan with those given in this paper, shows at once that this is
the case; for the ordinary system of calculation the stresses, in
addition to showing compression in the verticals, gives exactly twice the
amount of tension in the diagonals which they should have.

FIG. 1B.
________________________________________________________________________________
                                            |
          Top Flange Stresses.              |      Stresses in Diagonals.
                               Hor.    Ver. |
                                            |
C= 31.5  × 10/4.5  =         +70.00 = 31.50 |a = 70   -65         =+5.00 = 2.25
                                            |
   15.75 × 10/4.5  = 35                     |b =  "     "         =-5.00 = 4.00
                          \                 |
D                          > +65.00 = 22.75 |c = 65   -58.33-5    =+1.67 = 1.33
                          /                 |
   24    × 10/8    = 30                     |d =  "      "   "    =-1.67 = 1.75
                          \                 |
E                          > +58.33 = 14.58 |e = 58.33-55.83-1.67 =+ .83 =  .88
                          /                 |
   29.75 × 10/10.5 = 28.33                  |f =   "     "     "  =- .83 = 1.01
                          \                 |
F                          > +55.83 =  8.37 |g = 55.83-54.50- .83 =+ .50 =  .59
                          /                 |
   33    × 10/12   = 27.5                   |h =   "     "     "  =- .50 =  .61
                          \                 |
G                          > +54.50 =  2.72 |i = 54.50-53.67- .50 =+ .33 =  .43
                          /                 |
   33.75 × 10/12.5 = 27                     |j =   "     "     "  =- .33 =  .41
                          \                 |
H                          > +53.67 =  2.68 |k = 53.67-53.09- .33 =+ .24 =  .28
                          /                 |
   32    × 10/12   = 26.67                  |l =   "     "     "  =- .24 =  .24
                          \                 |
I                          > +53.09 =  7.97 |m = 53.09-52.67- .24 =+ .18 =  .20
                          /                 |
   27.75 × 10/10.5 = 26.42                  |n =   "     "     "  =+ .18 =  .16
                          \                 |
J                          > +52.67 = 13.17 |o = 52.67-52.36- .18 =+ .13 =  .11
                          /                 |
   21    × 10/8    = 26.25                  |p =   "     "     "  =- .13 =  .06
                          \                 |
K                          > +52.36 = 18.33 |
                          /                 |
   11.75 × 10/4.5  = 26.11                  |
                                            |
L= 23.5  × 10/4.5  =         +52.22 = 23.50 |
____________________________________________|___________________________________
                                            |
      _Bottom Flange Stresses._        |    _Stresses in Verticals._
                                            |
                          Hor.              |                              Ver.
           M same as C = 70.00              |    r = 15 - 4           = - 11.00
           N    "    D = 65.00              |    s =  5 + 2.25 - 1.75 = -  5.50
           O    "    E = 58.33              |    t =  5 + 1.33 - 1.01 = -  5.32
           P    "    F = 55.83              |    u =  5 +  .88 -  .61 = -  5.27
           Q    "    G = 54.50              |    v =  5 +  .59 -  .41 = -  5.18
           R    "    H = 53.67              |    w =  5 +  .43 -  .24 = -  5.19
           S    "    I = 53.09              |    x =  5 +  .28 -  .16 = -  5.12
           T    "    J = 52.67              |    y =  5 +  .20 -  .06 = -  5.14
           U    "    K = 52.36              |    z =  5 +  .11        = -  5.11
           V    "    L = 52.22              |
____________________________________________|___________________________________

--_The Engineer._

       *       *       *       *       *




A SPRING MOTOR.


An exhibition of a spring car motor was given at a recent date at the
works of the United States Spring Motor Construction Company, Twelfth
Street and Montgomery Avenue. As a practical illustration of the
operation of the motor a large platform car, containing a number of
invited guests and representatives of the press, was propelled on a track
the length of the shop. (This was in 1883.) The engine, if such it may be
called, was of the size which is intended to be used on elevated
railways. As constructed, the motor combines with a stationary shaft a
series of drums, carrying springs, and arranged so that they can be
brought into use singly or in pairs. Each spring or section has
sufficient capacity to run the car, and thus as one spring is used
another is applied. There is a series of clutches by which the drums to
which the springs are attached are connected, with a master wheel, which
transmits through a train of wheels the power of the springs to the
axles, of the truck wheels. The motor will be so constructed that it may
be placed on a truck of the width of the cars at present in use, and will
be nine feet long, with four traction wheels. It is proposed do away with
the two front wheels and platform, so that the front of the car may rest
on a spring to the truck. There will be an engine at each end of the
road, which, it is calculated, will wind up the springs in at least two
minutes' time.

While the mere construction of such a working motor involved nothing new,
the real problem involved consisted of the rolling of a piece of steel
300 feet long, 6 inches wide, and a quarter of an inch thick. Another
element was the coiling of this strip of steel preliminary to tempering.
To temper it straight was to expose the grain to unnecessary strain when
wound in a close coil. To overcome this was the most difficult part of
the work. At the exhibition the inventor gave an illustration of the
method which has been employed by the company. The strip of steel is
slowly passed through a retort heated by the admixture of gas and air at
the point of ignition in proportions to produce intense heat. When the
strip has been brought to almost a white heat, it is passed between two
rollers of the coiling machine. It is then subjected to a powerful blast
of compressed air and sprays of water, so that six inches from the
machine the steel is cold enough for the hand to be placed on it. After
this operation the spring is complete and ready to be placed on the
shaft. The use of the springs is said to be beyond estimate. They may be
employed to operate passenger elevators, the springs being wound by a
hand crank. It is understood that the French Government has applied for
them for running small yachts for harbor service. Among the advantages
claimed for this motor are its cheapness in first cost and in operating
expenses. It is estimated that an engine of twenty-five horse power will
be required at the station to wind the springs. If there be one at each
end of the line, the cost for fuel, engineer, and interest will not
exceed $100 per week. This will answer for fifty or any additional number
of cars. The company claims that by using twelve springs, each 150 feet
in length, an ordinary street car can be driven about twenty
miles.--_Phil. Inquirer_.

       *       *       *       *       *




CASTING CHILLED CAR WHEELS.


We show herewith the method employed by the Baltimore Car Wheel Company
in casting chilled wheels to prevent tread defects. The ordinary mode of
pouring from the ladle into the hub part of the mould, and then letting
the metal overpour down the brackets to the chill, produces cold shot,
seams, etc. In the arrangement here shown the hub core, A, has a concave
top, B, and the core seat, C, is convex, its center part being lower than
the perimeter of the top of the core. Figs. 3, 4, show the core, A, in
the side elevation and in plain. Fig. 2 is a core point forming a space
to connect the receiving chamber, E, above, with the mould by
passageways, D D, formed in the side of the top of the core. The combined
area of these passageways being less than that of the conduit, F, from
the receiving chamber, the metal is skimmed of impurities, and the latter
are retained in the receiving chamber, E. The entering metal flows first
to the lower hub part at H H, thence by the sprue-ways, G G, to the lower
rim part at J J, being again skimmed at the mouth of the sprue-ways. Thus
the rim fills as rapidly as the hub, and the metal is of a uniform and
high temperature when it reaches the chill.

[Illustration: CASTING OF CAR WHEELS.]

In the wheels made by this firm, every alternate rib is connected with
the rim, and runs off to nothing near the hub; the intermediate ribs are
attached to the hub, and diminish in width toward the rim.--_Jour.
Railway App._

       *       *       *       *       *




ELECTRICITY AND PRESTIDIGITATION.


The wonderful ease with which electricity adapts itself to the production
of mechanical, calorific, and luminious effects at a distance, long ago
gave rise to the idea of applying it to certain curious and amusing
effects that simple minds willingly style _supernatural_, because of
their powerlessness to find a satisfactory explanation of them.

[Illustration: FIG. 1.--RAPPING AND TALKING TABLE. ]

Who has not seen, of old, Robert Houdin's heavy chest and Robert Houdin's
magic drum? These two curious experiments are, as well known, founded
upon the properties of electro-magnets.

At present we shall make known two other arrangements, which are based
upon the same action, and which, presenting old experiments under a new
form, rejuvenate them by giving them another interest.

The first apparatus (Fig. 1), which presents the appearance of an
ordinary round center table, permits of reproducing at will the "spirit
rappings" and sepulchral voice experiments. The table support contains a
Leclanche pile, of compact form, carefully hidden in the part that
connects the three legs. The top of the table is in two parts, the lower
of which is hollow, and the upper forms a cover three or four millimeters
in thickness. In the center of the hollow part is placed a vertical
electro-magnet, one of the wires of which communicates with one of the
poles of the pile, and the other with a flat metallic circle glued to the
cover of the table. Beneath this circle, and at a slight distance from
it, there is a toothed circle, F, connected with the other pole of the
pile. When the table is pressed lightly upon, the cover bends and the
flat circle touches the toothed one, closes the circuit of the pile upon
the electro-magnet, which latter attracts its armature and produces a
sharp blow. On raising the hand, the cover takes its initial position,
breaks the circuit anew, and produces another sharp blow. Upon running
the hand lightly over the table, the cover is caused to bend successively
over a certain portion of its circumference, contacts and breakages of
the circuit are produced upon a certain number of the teeth, and the
sharp blow is replaced by a quick succession of sounds, or a tremulous
one, according to the skill of the medium whose business it is to
interrogate the spirits. As the table contains within it all the
mechanism that actuates it, it may be moved about without allowing the
artifice to be suspected.

[Illustration: FIG. 2.--ELECTRIC INSECTS.]

The table may also be operated at a distance by employing conductors
passing through the legs and under the carpet and communicating with a
pile whose circuit is closed at an opportune moment by a confederate
located in a neighboring apartment.

Finally, on substituting a small telephone receiver for the
electro-magnet, and a microtelephone system for the ordinary pile, we
shall convert the rapping spirits into talking ones. With a little
exercise it will be easy for the confederate to transmit the conversation
of the "spirits" in employing sepulchral tones to complete the illusion.

Fig. 2 represents a device especially designed as a parlor ornament. When
the plant is touched, the insects resting upon it immediately begin to
flap their wings as if they desired to fly away. These insects are
actuated by a Leclanche pile hidden in the pot that contains the plant.
The insect itself is nothing else than a mechanism analogous to that of
an ordinary vibrating bell. The body forms the core of a straight
electro-magnet, _c_, which is bent at right angles at its upper part, and
in front of which is placed a small iron disk, _b_, forming the animal's
head. This head is fixed upon a spring, like the armature of ordinary
bells, and causes the wings to move to and fro when it is successively
attracted and freed by the electro-magnet. The current is interrupted by
means of a small vibrating device whose mode of operation may be easily
understood by glancing at the section in Fig. 2. The current enters the
electro-magnet through a fine copper wire hidden in the leaves and
connected with the positive pole of the pile. The negative pole is
connected with the bottom of the pot. The wire from the vibrator of each
insect reaches the bottom of the flower-pot, but does not touch it. A
drop of mercury occupies the bottom of the pot, where it is free to move
about. It results that if the pot be taken into the hand, the exceedingly
mobile mercury will roll over the bottom and close the circuit
successively on the different insects, and keep them in motion until the
pot has been put down and the drop of mercury has become immovable.

       *       *       *       *       *




PORTABLE ELECTRIC SAFETY LAMPS.


One of the most difficult problems that daily presents itself in large
cities is how to proceed without danger in the search for leakages in gas
mains, or in attempts to save life in houses accidentally filled with
explosive gases. The introduction of a flame into such places leads in
the majority of cases to accidents whose consequences cannot be
estimated. The reader will remember especially the explosion which
occurred some time ago in St. Denis Street, Paris, and which killed a
considerable number of persons. It has, therefore, been but natural to
think of the use of electricity, which gives a bright line without a
flame, in order to allow life-saving corps and firemen to enter buildings
filled with an explosive mixture, without any risk whatever.

[Illustration: FIG. 1.--ELEVATION (Scale 1/25).]

Several electricians have proposed ingenious portable apparatus for this
purpose, and, among these, Mr. A. Gerard, whose device we illustrate
herewith. In this system the electric generator is stationary, and
remains outside the building. This, along with all the rest of the
apparatus, is mounted upon a carriage. The operator, instead of carrying
a pile to feed the lamp, drags after him a very elastic cable containing
the two conductors. This "Ariadne's thread" easily follows all
sinuosities, and adapts itself to all circumvolutions. The entire
apparatus, being mounted upon a carriage, can be easily drawn to the
place of accident like a fire engine.

[Illustration: FIG. 2.--PLAN (Scale 1/25).]

_General Description_.--Fig. 1 shows the carriage. In the center, over
the axle, is mounted a dynamo-electric, machine, D, driven by a series of
gear wheels that are revolved by winches, MM. Upon the shaft, A, is fixed
a hand wheel, V, designed to regulate the motion. In the forepart of the
carriage are placed two windlasses, TT, permanently connected with the
terminals of the dynamo. Upon each of these is wound a cable formed of
two conductors, insulated with caoutchouc and confined in the same
sheath. Each windlass is provided with five hundred feet of this cable,
the extremity of which is attached to two lanterns each containing an
incandescent lamp. These lanterns, are inclosed in boxes, BB, with double
sides, and cross braced with springs so as to diminish shocks. Under the
windlass there is a case which is divided into two compartments, one of
which contains tools and fittings, and the other, six carefully packed
incandescent lamps, to be used in case of accident to the lanterns. At
the rear end of the carriage there is a hinged bar, C, designed to
support it at this point and give it greater stability during the
maneuvers. The stability is further increased by chocking the wheels.

[Illustration: FIG. 3.--HAND LANTERN (Scale 1/4).]

_Maneuver of the Apparatus_.--The carriage, having reached the place of
accident, is put in place, its rear end is supported by the bar, C, the
wheels are chocked, and the winches are placed upon the dynamo gearing.
Two strong men selected for the purpose now seize the winches and begin
to revolve them, and the lamps immediately light while in their boxes.
Another man, having opened the latter, takes out one of the lanterns and
enters the dangerous place, dragging after him the elastic cable that
unwinds from the windlass. Two men are sufficient to turn the winches for
five minutes; with a force of six men to relieve one another the
apparatus may therefore be run continuously.

[Illustration: FIG. 4.--POLE LANTERN (Scale 1/4).]

The dynamo, which is of strong and simple construction, is inclosed in a
cast iron drum, and is consequently protected against accident. With a
power of 25 kilogrammeters it furnishes a current of 40 volts and 7
amperes, which is more than sufficient to run two 50-candle incandescent
lamps. The winches are removable, and are not put upon the shaft until
the moment they are to be used.

The windlasses, as above stated, are permanently connected with the
terminals of the dynamos. The current is led to them through their
bearings and journals. Their shaft is in two pieces, insulated from one
another. One extremity of the cable is attached to these two pieces, and
the other to the lantern. Each windlass is provided with a small winch
that allows the cable to be wound up quickly.

[Illustration: FIG. 5.--WINDLASS (Scale 1/10).]

The two lanterns are different, on account of the unlike uses to which
they are to be put. One of them is a hand-lamp that permits of making a
quick preliminary exploration. The second is to be fixed by a socket
beneath it to a pole that is placed along the shafts of the carriage.
This lantern, upon being thrust into a chimney, shaft, or well, permits
of a careful examination being made thereof. As the handle terminates in
a point; it may be stuck into the ground, to give a light at a sufficient
height to illuminate the surroundings.

The hand lantern consists of a base, P, provided with three feet. At the
top there is a threaded circle to which is attached a movable handle, K,
that is screwed on to a ring, C. These three pieces, which are of bronze,
are connected by 12 steel braces, E, that form a protection for the
glass, M. The lantern is closed above by a thick glass disk, G. The
luminous rays are therefore capable of spreading in all directions. Tight
joints are formed at every point by rubber or leather washers.

[Illustration: FIG. 6.--LANTERN BOX (Scale 1/10).]

In the center of the lantern is placed the incandescent lamp. This is
held in a socket, and is provided with two armatures to which the
platinum wires are soldered. Two terminals, b, are affixed to the lamp
socket. Beneath the lantern there is a cylindrical box provided with a
screw cap. In one side of this box there is a tubulure that gives passage
to the electric cable whose conductors are fastened to the terminals. A
conical rubber sleeve, R, incloses the cable, which is pressed by the
screw cap, S. A special spring, Y, attached at one end to the top of the
lantern, and at the other to the cable, X, is designed to deaden the too
sudden shocks that the lantern might be submitted to, and that would tend
to pull out the cable.

As a result of the peculiar arrangement of this lantern, the lamp is
constantly surrounded with a certain quantity of air that would certainly
suffice to consume the carbons in case of a breakage of the globe without
allowing any lighted particles to escape to the exterior. Besides, should
the terminals become unscrewed, and should the conductors thus rendered
free produce sparks, the latter would be prevented from reaching the
exterior by reason of the absolute tightness of the box. In case the
incandescent lamp should get broken, the only inconvenience that would
attend the accident would be that the man who held the lantern would be
for a moment in the dark. When he reached the carriage, it would be only
necessary for him to take off the glass disk, take the broken lamp out of
its socket, insert a new one, and then put the glass top on again.--_Le
Génie Civil_.

       *       *       *       *       *

Voltaic batteries containing solutions of ammonium chloride and zinc
chloride can, according to the recent researches of M. Onimus, be
converted into dry piles by mixing these solutions with plaster of Paris,
and allowing the mixture to solidify. If mixtures of ferric oxide and
manganese peroxide with plaster of Paris are employed, the electromotive
force is slightly higher than with plaster of Paris alone; and when
ferric oxide is used, the battery quickly regains its original strength
on breaking the circuit. When the battery is exhausted, the solid plaster
of Paris has simply to be moistened again with the solution.

       *       *       *       *       *




THE ELECTRIC DISCHARGE AND SPARK PHOTOGRAPHED DIRECTLY WITHOUT AN
OBJECTIVE.


The study of the form and color that electric discharges exhibit,
according to the different ways in which they are produced, has already
enticed a certain number of amateurs and scientists. Every one knows the
remarkable researches of the lamented Th. Du Moncel on the induction
spark, and during the course of which he, in 1853, discovered that
phenomenon of the electric efflux which has since been the object of
important researches on the part of several physicists and chemists,
among whom must be cited Messrs. Thenard, Hautefeuille, and Chapuis.
Twenty years ago, Mr. Bertin, who was then Professor at the Faculty of
Strassburg, and who was afterward subdirector of the normal school, was
directing his researches upon the electric discharges produced by high
tension apparatus, plate machines, and Leyden jars. He thought, with
reason, that, on account of its rapidity and complexity, a portion of the
phenomenon must escape the eye of the observer, and so the idea occurred
to him to photograph the discharge in order to afterward study its forms
more at his leisure. We have recently had an opportunity of seeing a
negative which was obtained by him at that epoch; but the photographic
processes then in use probably did not allow him to obtain others that
were as satisfactory, and he had given up this kind of study, when, last
year, he had an opportunity of speaking of it to the well known
manufacturer Mr. F. Ducretet, whom he induced to take it up and employ
the new gelatino-bromide process. Unfortunately, he died before these
experiments were begun, and was unable to see the realization of his
project. Mr. Ducretet did not abandon the idea, but constructed the
necessary apparatus, and obtained the results that we now place before
our readers.

[Illustration: FIG 1.]

His apparatus, which contains no photographic objective, consists of an
oblong case, ABCD, made of red glass and resting upon an ebonite table
supported by one leg (Fig. 1). In the top of the case, as well as in the
two sides, AD and BC, are apertures that are closed by ebonite cylinders
through which slide, with slight friction, copper rods, HLN. In the leg
of the table there is a copper rack which may be maneuvered from the
interior by a pinion, and which communicates electrically with a
terminal, E. The upper part of this rack, which enters the glass case, is
threaded, so that there may be affixed to it either a metallic or an
insulating disk. The rods, HLN, are likewise threaded, so that there may
be affixed to their internal extremities balls, points, combs, and disks
of metal or of insulating material at will.

[Illustration: FIG 2.]

In short, we have here a transparent box (impermeable to photogenic rays)
into which electricity may be led by means of four conductors that are
arranged two by two in a line with each other, or in perpendicular
positions, and that may be made to approach or recede from one another by
maneuvering them from the exterior. This very simple arrangement answers
every requirement, and, upon placing a sensitized plate in the vicinity
of the conductors, permits of photographing the electric discharge
directly and, so to speak, before the eyes of the operator.

As a source of electricity, use is made of a bichromate of potash
battery of 6 elements, capable of giving 10 volts and 15 amperes. The
current from this battery is converted into a current of high tension by
means of a strong induction coil capable of giving sparks more than eight
inches in length. The discharge shown in Fig. 4 was obtained by means of
a Holtz machine. Each experiment lasted less than a second.

[Illustration: FIG. 3.]

Figs. 2 and 3 represent the efflux that occurred under; the following
conditions: The disk, P, was of metal, and was connected with the
negative pole of the induction coil; and upon it was laid the
photographic plate with the sensitized film downward, and consequently
touching the disk. This is what produced the opaque circle in the center.
Then the photographic plate was entirely covered with a thin ebonite
plate, above which there was a second one supported by small wedges, so
as to allow air to circulate between them. Finally, upon this second
ebonite plate there was placed another photographic plate, with its
sensitized film upward and directly in contact with an upper metallic
disk, and connected with the positive pole of the coil by the conductor,
L. An inspection of Figs. 2 and 3 shows that the, efflux does not possess
the same form at the two poles. We remark at the positive pole a quite
wide opaque circle surrounded by a sort of aureola composed of an
infinite number of very delicate rays, while at the negative pole the
aureola seems not to have been able to spread. We see, moreover, the same
phenomenon in examining Fig. 4 (which represents the efflux obtained by
means of a Holtz machine), but this time in a horizontal direction. The
photographic plate was here placed upon the non-conducting disk, P. As
the sensitized film was upward, it was put in contact with the balls at
the extremity of the conductors, H and N.

[Illustration: FIG. 4.]

It will be seen here again that the efflux spreads out widely at the
positive pole, while it is contracted at the other. The conducting balls
were spaced 0.04 inch apart. A spark leaped from one to the other at the
moment the current was being interrupted.

In Fig. 5 we are enabled to study with more ease a spark obtained with
nearly the same arrangement. The balls, H and N, did not here rest
directly upon the sensitized film, but upon two small sheets of tin
cemented to the extremities of the plate at 0.06 inch apart. In addition,
the source employed was not the Holtz machine, but the pile with
induction coil. Two nearly parallel sparks were obtained. It will be seen
that these are very complex. Each of them seems to be formed of four
lines of different sizes, entangled with one another and presenting
different sinuosities. Aside from this, the plate is traversed for a
space of 0.04 of an inch by curved lines running from one pole to the
other, and exhibiting numerous sinuosities.

[Illustration: FIG. 5.]

Fig. 6 represents a discharge that occurred under the following
circumstances: The disk, P, being metallic and connected with one of the
poles, there was placed upon it a thin ebonite plate of the same
dimensions as the photographic one, and then the latter with the
sensitized pellicle upward. Finally, the pellicle was put in contact with
the upper conductor, L, which terminated in a ball and was connected with
the other pole of the induction coil.

It will be seen that, despite the two dielectrics (ebonite and glass)
interposed, and the opacity of one of them, the efflux that occurred
around the disk, P, is quite sharply reproduced upon the sensitized plate
by a circle like that which we observed in Figs. 2 and 3. It will be
seen, besides, that an infinite number of ramifications in every
direction has been produced around the ball, and we can follow the travel
of the spark that leaped between the ball and disk in two directions
situated in the prolongation of one another.

Under the two principal and clearly marked lines that this spark made
there are seen two other, very pale and much wider ones, that present no
sinuosities parallel with the first.

The results of these experiments are very curious. The position of the
plates was varied in 18 different ways, as was also the form of the
conductors. We have spoken of those only that appear to us to present the
most interest. Unfortunately, notwithstanding the skill of the engraver,
it is impossible to render with accuracy all the details that are seen
upon examining the negative. The proofs that have been printed upon paper
present much less sharpness than the negative, for there are certain
parts of the figures on the glass that do not show in the print.

[Illustration: FIG. 6.]

We have been content here to make known the results obtained, without
drawing any conclusions from them. It is to be hoped that these
experiments, which can be easily repeated by means of the apparatus
described above, will be repeated and discussed by electricians, and that
they will contribute toward making known to us the nature of the
mysterious agent that will give its name to our era.--_G. Mareschal,
in La Lumiere Electrique._

       *       *       *       *       *




THE TRUE CONSTANT OF GRAVITY.


Many of the readers of this journal may like to participate in the
discussion of the following proposition. The statement is this:

The space through which a body, near the surface of the earth, at mean
latitude, _in vacuo_, descends by virtue of the accelerating force of
gravity in 1/1000 of an hour is precisely 2,500 geometric inches = 100
geometric cubits = the side of a square geometric acre.

[The geometric inch is taken, in accordance with the view of Sir John
Herschel, at 1/1,000,000,000 of twice the polar axis of the earth, and
equals 1-1/1000 English inches very nearly.]

The strict decimal relation of the proposition is shown by the following
table. It has been tested by Clairaut's theorem, and by other existing
expressions, and has been found to agree, far within the probable limits
of errors in observation, with the most approved values of the constant.
In fact, it is contained in the existing expressions; but the _decimal_
relation does not appear unless we state the unit of linear measure as a
decimal of the earth's semi-polar axis, and, at the same time, divide the
circle, both for time and for general purposes, _geometrically, i.e._, by
strict decimalization upon the hour-angle. A mathematical reason
underlies the proposition.

Time in       Acquired    Squares   Total      Ratio of       Descent in
Thousandths   Velocity,   of the    Descent,   Spaces, Each   Successive
of an Hour.   Cubits.     Time.     Cubits.    Interval of    Intervals,
                                               Time.          Cubits.

     1           200          1         100          1             100
     2           400          4         400          3             300
     3           600          9         900          5             500
     4           800         16       1,600          7             700
     5         1,000         25       2,500          9             900
     6         1,200         36       3,600         11           1,100
     7         1,400         49       4,900         13           1,300
     8         1,600         64       6,400         15           1,500
     9         1,800         81       8,100         17           1,700
    10         2,000        100      10,000         19           1,900

So that--
                                                    Cubits.   Acre Sides.
In 1/10,000 of an hour, the total
descent =                                                1  =       1/100

In 1/1000 of an hour, the total descent =              100  =      1

In 1/100 of an hour, the total descent =            10,000  =    100

And so on, in strict _decimal_ relation with the earth's semi-polar axis.

A two-fold reason why the constant for latitude 45° is vastly better than
any other, is in its having this simple relation with the semi-axis, and
at the same time a less complex way of applying the correction for
latitude.

JACOB M. CLARK.

New York, February, 1885.

       *       *       *       *       *




ORIGIN OF THUNDERSTORMS.


At the recent congress of German medical men and physicists, Dr. S.
Hoppe, of Hamburg, read a paper in which he sought to show that the
electricity of thunderstorms is generated by the friction of vapor
particles generated by the evaporation of water. This opinion was
strengthened by several experiments in which compressed cold air was
allowed to rush into a copper vessel containing warm moist air, thus
generating a large amount of electricity. He concludes that the rise of a
column of warm moist air into the colder atmosphere above will be
followed by a thunderstorm if it acquires sufficient velocity to prevent
neutralization of the electricity generated by the friction of the air.
Hence, in his opinion, open districts denuded of forests are more liable
to thunderstorms than wooded regions, where the trees forbid the rise of
humid air currents.

       *       *       *       *       *




IMPROVISED TOYS.


Do our readers remember all those ingenious toys which our mothers and
sisters improvised in order to amuse us? We took a walk into the country,
and our eldest sister or our mother picked a wild poppy, turned its red
petals back and encircled them with a thread, and stuck a sprig of grass
into the seed vessel to represent a headdress of feathers. Here was a
fresh and pretty doll (Fig. 1). Another day it was the season of lilacs.
The children gathered branches by the armful, and from these the mother
picked off the flowers and strung them one by one with a needle. Here was
a bracelet or a necklace. An acorn was picked up in the woods, the mother
carved it with a pen-knife, and behold a basket. From a nutshell she made
a boat, and from a green almond a rabbit. Sometimes she carved the
rabbit's ears out of the almond itself, but in most cases they were made
from a pretty rose-colored radish.

[Illustration: FIG. 1.--Doll made of a Wild Poppy.]

Do you remember the cork from which, by the aid of a few long needles for
bars, an ingenious fly-cage was formed? And the castle of cards, four,
five, and eight stories high? And then those famous card tents in a row,
that fell one after another when the first one in the line was
overturned?

[Illustration: FIG. 2.--Hygrometric Doll; its Dress Colored with
Chloride of Cobalt.]

How we passed the evenings with our eyes fixed upon our mothers, who
patiently, with their skillful scissors, cut horses and dogs out of old
white, red, and blue cards! And how many plays, without costing a cent,
served to amuse the children by exercising their ingenuity! The mother
marked at hazard five dots upon a sheet of paper. The question was to
draw a man, one of the dots showing the place of the head and the other
four the feet and hands.

[Illustration: FIG. 3.--Old Man made of Lobster's Claws.]

When the dessert was brought upon the table, it became a question of
manufacturing a head out of an orange. That is not very difficult; two
holes for the eyes, a large slit for the mouth, and nothing easier than
to simulate the teeth and nose. The head was placed upon a napkin
stretched over the top of a champagne glass. This was one of our great
amusements. The napkin was drawn ultimately to the right and left, and
this moved the head and caused it to assume most comical positions. But
what caused irresistible laughter was when a sly hand pressed the head
and made it open its mouth wide. And then what pigs we manufactured with
a lemon perched upon four matches!

[Illustration: FIG. 4.--Crocus Flowering in a Perforated Pot.]

Without mentioning Chinese shadows, how many cheap amusements there are
that can be varied to infinity merely by various combinations of the
fingers interlocked in diverse manners!

[Illustration: FIG. 5.--1. Paper Cross. 2. Method of Making the
Cross. 3. Rabbits Made of Green Almonds. 4. Basket Made of Sedges. 5.
Acorn Basket. 6. Fly-cage Made of a Cork.]

All such amusements were much in vogue in former times, but we are
assured that to-day mothers are less conversant with these curious and
droll inventions, which were once transmitted like the tales of Mother
Goose. They buy playthings for their children at great expense, and allow
the latter to amuse themselves all by themselves. The toy paid for and
given, the child is no longer in their mind. Those mothers who have
preserved the traditions of these little pastimes, and know how to
skillfully vary them, find therein so many resources for amusing their
children. Then it is so pleasant to see the eyes of the latter eagerly
fixed upon the scissors, and to hear their exclamations of pleasure and
their fresh laughter when the paper is transformed under expert fingers
into a boat, house, or what not!

[Illustration: FIG. 6.--The Lesson in Drawing.--An Illustrated
Five-spot of Hearts.]

It has required millions of mothers and nurses to put their wits to work
to amuse their children in order to form that collection of charming
combinations that at present constitutes a sort of science. Mr. Gaston
Tissandier not long ago conceived the happy idea of bringing together in
an illustrated volume a description of some of these improvised toys and
amusing plays, and it is from this that the accompanying illustrations
(which sufficiently explain themselves) are taken.

       *       *       *       *       *




THE ÆOLIAN HARP.


The Æolian harp is a musical instrument which is set in action by the
wind. The instrument, which is not very well known, is yet very curious,
and at the request of some of our readers we shall herewith give a
description of it.

[Illustration: FIG. 1.--KIRCHER'S ÆOLIAN HARP.]

According to a generally credited opinion, it is to Father Kircher, who
devised so many ingenious machines in the seventeenth century, that we
owe the first systematically constructed model of an Æolian harp. We must
add, however, that the fact of the spontaneous resonance of certain
musical instruments when exposed to a current of air had struck the
observers of nature in times of remotest antiquity.

Without dwelling upon the history of the Æolian harp, we may say that in
modern times this instrument has been especially constructed in England,
Scotland, Germany, and Alsace. The Æolian harp of the Castle of Baden
Baden, and those of the four turrets of Strassburg Cathedral are
celebrated.

[Illustration: FIG. 2.--FROST & KASTNER'S IMPROVED ÆOLIAN HARP.]

We shall first describe Kircher's harp, which this Jesuit savant
constructed according to an observation made by Porta in 1558. The
instrument consists of a rectangular box (Fig. 1), the sounding board of
which, containing rose-shaped apertures, is provided with a certain
number of strings stretched over two bridges and fastened to pegs at the
extremities. This box carries a ring that serves for suspending it.
Kircher recommends that the box be made of very sonorous fir wood, like
that employed in the construction of stringed instruments. He would have
it 1.085 meters in length, 0.434 meter in width, and 0.217 meter in
height, and would provide it with fifteen catgut strings, tuned, not like
those of other instruments to the third, fourth, or fifth, but all in
unison or to the octave, in order, says he, that its sound shall be very
harmonious. The experiments of Kircher showed him the necessity of
employing a sort of concentrator in order to increase the force of the
wind, and to obtain all the advantage possible from the current of air
that was directed against the strings. The place where the instrument is
located should not, according to him, be exposed to the open air, but
must be a closed one. The air, nevertheless, must have free access to it
on both sides of the harp. The force of the wind may be concentrated upon
such a point in different ways; either, for example, by means of conical
channels, or spiral ones like those used for causing sounds to reach the
interior of a house from a more elevated place, or by means of a sort of
doors. These latter, two in number, are adapted to a kind of receptacle
made of boards and presenting the appearance of a small closet. In the
back part of this receptacle there is a slit, and in front of this the
harp is hung in a slightly oblique position. The whole posterior portion
of the apparatus must be situated in the apartment, while the doors must
remain outside the window (Fig. I). In later times the Æolian harp has
been improved by Messrs. Frost and Kastner, whose apparatus is
represented in Fig. 2. It consists of a rectangular box with two sounding
boards, each provided with eight catgut strings. In order to limit the
current of air and to bring it with more force against the strings, two
wings are adapted near the thin surfaces opposed to the wind, so that the
current may reach each group of cords on passing through the narrow
aperture between the obliquely inclined wing and the body of the
instrument. The dimensions of the resonant box are as follows: height,
1.28 meters; width, 0.27 meter; and thickness, 0.075 meter. Distance
between the two bridges, or length of the sonorous portion of the cords,
about 1 meter; width of the wings, 0.14 meter. Distance between the
sounding board and the wings, 0.42 meter. Inclination of the wings, 50
degrees.

[Illustration: FIG. 3.--ÆOLIAN HARP IN THE OLD CASTLE OF BADEN
BADEN.]

The celebrated Æolian harps of the old castle of Baden Baden are entirely
different, and merit description. One of them (Fig. 3) is formed of a
resonant box, the construction of which differs from that of Æolian harps
with a rectangular box, in that it is prolonged beyond the place occupied
by the strings, and is rounded off behind. In the opposite side there are
two long and narrow apertures. To prevent the apparatus from being
injured by the weather, it is inclosed in a sort of case occupying the
recess of the window in the old ruined castle in which it is exposed.
Behind the harp there is a wire lattice door, the purpose of which seems
to be to protect the instrument against the attempts of robbers or the
indiscreet contact of tourists. We annex to the general view of the
instrument a front and profile plan (Fig. 4). The Æolian harp has often
inspired both writers of prose and poetry. Chateaubriand, in _Les
Natchez_, compares its sounds to the magic concerts that the celestial
vaults resound. Without attributing such effects to the instrument, it
must be admitted that it possesses remarkable properties, which act upon
the nervous system and cause very different impressions, according to the
temperament of those who listen to its accords.

[Illustration: FIG. 4.--PLAN OF THE BADEN BADEN INSTRUMENT.]

Hector Berlioz, in his _Voyage Musicale en Italie_, has given as follows
the curious effects that an Æolian harp produced upon his lively and
impassioned imagination: "On one of those gloomy days that sadden the end
of the year, listen, while reading Ossian, to the fantastic harmony of an
Æolian harp swinging at the top of a tree deprived of verdure, and I defy
you not to experience a profound feeling of sadness and of _abandon_, and
a vague and infinite desire for another existence."

An English physician, Dr. J.M. Cox, in his practical _Observations_ upon
dementia, asserts that unfortunate lunatics have been seen whose
sensitiveness was such that ordinary means of cure had to be given up
with them, but who were instantly calmed by the sweet and varied accords
of an Æolian harp. Other observers narrate that they have heard the
efficacy of Aeolian sounds spoken of in Scotland for producing sleep.

Telegraph wires are often, under the influence of the winds, submitted to
vibrations which reproduce the phenomena of the Aeolian harp. The
electric telegraph, which, before the construction of the Kehl bridge,
directly traversed the Rhine, very frequently resounded, and the observer
who placed his ear against the poles on the bank of the river was enabled
to hear something like a far-off sound of bells.--_La Nature_.

       *       *       *       *       *




PHYSICS WITHOUT APPARATUS.

MANUFACTURE OF ILLUMINATING GAS.


[Illustration: FIG. 1.--PRODUCTION OF ILLUMINATING GAS.]

Burn a piece of paper of about the size of the hand upon a clean
porcelain plate, and this will serve to show the phenomena of
carbonization and the formation of empyreumatic products under the action
of heat. Under the burned paper there will be found a yellowish deposit
which sticks to the fingers, and which consists of oil of paper produced
by distillation. An idea of the production of illuminating gas through
the distillation of coal may be easily given by means a single clay pipe.
Upon filling the bowl of this with fragments of coal, closing the opening
with clay, and, after the latter is dry, placing the bowl in a coal fire
so that the stem shall project, gas will soon be observed issuing from,
the latter, and, when lighted, will give a very bright flame. If the pipe
seems to be a little too costly, recourse maybe had to a large piece of
wrapping paper rolled into the form of a cornucopia, and held in the left
hand by means of the pointed end. If, after an aperture has been made in
this near the point, the base be lighted, the heat developed by the flame
will produce a sort of distillation of the organic matter of the paper,
and the empyreumatic and gaseous products will rise in the cone, and make
their exit through the orifice, where they may be lighted with a match
(Fig. 1). It goes without saying that this experiment lasts but a few
seconds; but, as short as this period is, it is sufficient to give a
demonstration of the production of illuminating gas through the
distillation of organic matters. Care should be taken not to set anything
on fire while performing it, and it is well to operate over a pavement,
and far from any inflammable materials.


ELASTICITY OF BODIES.

[Illustration: FIG. 2.--EXPERIMENT ON THE ELASTICITY OF BODIES.]

Mould a piece of fresh bread with the fingers so as to give it the size
and shape shown in Fig. 2. If this object be placed upon a wooden table,
and a hard blow be given it with the fist, it will be found impossible to
put it permanently out of shape. However hard be the blow, the elastic
material, although flattened for an instant, will always resume its
original form. If the object be thrown on the floor with all one's might,
the result will be the same; its elasticity will always cause it to
spring back to its original form. The experiment will only succeed when
the bread that is used is very fresh and soft.

       *       *       *       *       *




SCIENTIFIC AMUSEMENTS.


_The Dance of the Electrified Puppets_.--We have already pointed out a
means of obtaining electrical manifestations without recourse to a
machine, and shall now describe a very easily performed experiment--the
dance of the electrified puppets.

[Illustration: FIG. 1.--DANCE OF THE ELECTRIFIED PUPPETS.]

Procure a pane of glass about 10 inches in width and 14 in length, and
support it between two large books, as shown in Fig. 1. The glass must be
inserted in the books in such a way that it shall be an inch and a
fraction above the surface of the table. Then, with a pair of scissors,
cut out of a piece of tissue-paper a number of figures, such as men,
women, clowns, frogs, etc. These little figures must not exceed
three-quarters of an inch in length. We show some of actual size in Fig.
1. They may be cut out of papers of different colors, so as to give
variety to the scene. After they are prepared they are to be placed in
the ball-room, that is to say, in the space between the books, glass, and
table. They should be laid flat upon the table, and alongside of one
another. Now rub the upper surface of the glass vigorously with a piece
of silk or woolen, and, in a few instants, the figures will be attracted
by the electricity, and suddenly stand up straight and jump up to the
transparent ceiling of their ball-room. Then they will be repelled, and
again attracted, and thus keep up a lively dance. When the rubbing is
stopped, the dance continues spontaneously for some little time, and even
the contact of the hand suffices to animate the figures. In order that
this experiment shall prove a success, the glass used must be very dry,
as well as the fabric with which it is rubbed. If the latter be warmed,
the manifestation will be more rapid and energetic. Silk answers better
than woolen.

[Illustration: FIG. 2.--SILHOUETTE PORTRAITS.]

_Silhouette Portraits_.--Take a large sheet of paper, black on one side
and white on the other, and affix it to the wall, white surface outward,
by means of pins or tacks. Place a very bright light upon the table, at a
proper distance, and allow the person whose portrait it is desired to
form to stand between it and the wall (Fig. 2). Then, with a pencil, draw
the outlines of the shadow projected. While this is being done, it is
very necessary that the subject shall keep perfectly immovable. When the
outlines are sketched, remove the paper from the wall and cut out the
portrait. After this, all that remains to be done is to turn the portrait
over and paste it to a sheet of white paper. The silhouette is profiled
in black, and if the operation be skillfully performed, the resemblance
will be perfect.--_La Nature_.

       *       *       *       *       *




HOW TO BREAK A CORD WITH THE HANDS.


Our readers have often seen grocers' clerks or employes of business
houses break the string with which they had tied up a package, by seizing
it with the hands, bringing the latter close together, and then suddenly
separating them with a quick movement. If it be thought that this quick
motion is sufficient, let any one try it, and he will merely cut his
hands without breaking the string, provided the latter has some little
strength. In order to succeed, the cord must be arranged in a certain
manner, as we shall explain.

[Illustration: MODE OF BREAKING A CORD WITH THE HANDS.]

The cord to be broken is placed upon the left hand, and one of its ends
is passed over the other in such a way as to form a cross, and the end
forming the shorter part of the cross is wound around the fingers (it
should be left long enough to make several turns). The other end is then
turned back and wound around the right hand, so as to leave a space of
about eighteen inches between the latter and the left hand. If these
directions are properly followed, the string should have the form of a Y
in the middle of the hand, as shown in the lower figure of the
accompanying engraving.

It is only necessary after this to close the hand, after seeing that the
Y is very taut, and to seize the cord with the other hand, as shown in
the upper figure. This done, the two hands are brought together and then
suddenly separated so as to give a quick pull on the point of junction of
the Y-shaped branches, which form a true knife. It will be readily seen
that as the cord is broken suddenly the shock does not have time to
transmit itself to the hands. This is an interesting demonstration of the
principle of inertia.

       *       *       *       *       *




AN AQUATIC VELOCIPEDE FOR DUCK HUNTING.


The curious apparatus that we represent in Fig. 1, from an old English
engraving of 1823, is an aquatic velocipede which was utilized with
success during the entire winter of 1822. An amateur employed it for
hunting ducks upon the numerous streams of Lincolnshire, and, as it
appears, obtained very good results from it. The device is very
ingenious. It consists of three floats of from 1,800 to 2,000 cubic
inches capacity, made of copper or tin plate. These are full of air, and
must be perfectly tight. They are held together by arched iron rods, as
shown in the cut, so as to form the three angles of an isosceles
triangle. These rods are provided in the center with a saddle for the
velocipedist to sit upon. The apparatus floats upon the water and
sustains the hunter, whose feet are provided with quite short paddles, by
means of which he navigates, and steers himself.

[Illustration: FIG. 1.--AN AQUATIC VELOCIPEDE OF 1822.]

The amusing engraving of this velocipede, which is mentioned under the
name of the _aquatic tripod_, puts us in mind of another document of the
same kind that we have seen in the gallery of prints of the National
Library. It is a naively drawn lithograph representing a trial of
velocipedes in the Luxembourg Garden, at Paris, in 1818. In Fig. 2 we
give a reduced copy of it. It will be seen that in 1818 velocipedes were
made of wood and were provided with two wheels--one in front, and the
other behind. The propelling was done by alternately placing the feet on
the ground.

[Illustration: FIG. 2.--A TRIAL OF VELOCIPEDES IN 1818.]

       *       *       *       *       *




A SUNSHINE RECORDER.


The apparatus is of simple construction. It consists of a glass sphere
silvered inside and placed before the lens of a camera, the axis of the
instrument being placed parallel to the polar axis of the earth. The
whole arrangement will be readily understood by an inspection of Fig. 1.
The light from the sun is reflected from the globe, and some of it,
passing through the lens, forms an image on a piece of prepared paper
within the camera. In consequence of the rotation of the earth, the image
describes an arc of a circle on the paper, and when the sun is obscured,
this arc is necessarily discontinuous. The image is not a point, but a
line, and in certain relative positions of the sphere, lens, and paper,
the line is radial and very thin, so that the obscuration of the sun for
only one minute is indicated by a weakening of the image.

[Illustration: FIG. 1.]

In the actual apparatus the sphere is an ordinary round-bottomed flask
about 95 mm. in diameter, and the lens a simple double convex lens of
about 90 mm. focal length. The sensitive paper employed is the ordinary
ferro-prussiate now so much used by engineers for copying tracings. This
was selected in consequence of the ease with which the impression is
fixed, for the paper merely requires to be washed in a stream of water
for six minutes, no chemicals being necessary. When the paper is dry,
radial lines containing between them angles of 15° are drawn from the
center of the circular impression, and thus give the hour scale, the time
of apparent noon being of course given by a line passing through the plan
of the meridian. Fig. 2 is a copy of the record of June 27, 1884; in the
morning the sun shone brightly, toward noon clouds began to form, and in
the afternoon the sky was hazy. The field in which the instrument is
placed is surrounded by trees, so the ends of the trace are cut off
sharply by shadows.

[Illustration: FIG. 2.]

With the alteration of declination of the sun, the light entering the
camera is reflected from different portions of the sphere, and an
alteration of the position of the focus results. This may be corrected in
three ways; by moving (1) the paper, (2) the lens, or (3) the sphere. In
the present apparatus the first method has been adopted, and now the
camera is about twice as long as it was in June. As a consequence, the
circular image is enlarged, and the light therefore weakened, and that at
a time of year when it can least be spared. If the focus is altered by
moving the lens, the winter circle is small and the summer circle is much
larger. This would perhaps be too much to the advantage of the winter
sun. If, however, the lens and paper are maintained at a constant
distance, and the sphere alone moved, the circles are more nearly of the
same diameter throughout the year, the winter one still remaining the
smallest. This seems, therefore, to be the most advantageous arrangement,
and the one that will be adopted in future. It may be possible also to
find positions for the sphere, lens, and paper such that the intensity of
the image is a true measure of the intensity of the sun's light; at
present, however, this has not been done, the want of sunlight and the
press of official work having prevented the carrying out of the necessary
experiments. A more sensitive paper might also be used with advantage,
and in observatories where photographic processes are carried on daily
there would be no difficulty on this score, but my principal object was
to devise some economical instrument requiring only easy manipulation, so
that at a considerable number of places the instruments might be set up,
giving a more useful average of the duration of sunshine than can be
obtained from only a few stations. The instrument also gives a record
when the sun is shining through light clouds; in this case the image is
somewhat blurred and naturally weakened, and it may be difficult or
impossible to employ any scale for measuring the intensity under such
conditions, but it must be remembered that, even when the sun is shining
in this imperfect manner, it is really doing work on the vegetation of
the earth, and deserves to be recorded.

It may be well to say that the instrument is in no way protected. Some
friends, whose opinion I highly value, urged me to patent it; but as I
strongly hold the view that the work of all students of science should be
given freely to the world, the apparatus was described at the Physical
Society a few hours after the advice was given, lest the greed of filthy
lucre should, on further deliberation, cause me to act contrary to my
principles.--_Herbert McLeod, Nature_.

       *       *       *       *       *




SKELETON OF A BEAR FOUND IN A CAVE IN STYRIA, AUSTRIA.


In the limestone mountains of the Austrian Alpine countries, numerous
large caverns and caves are found, some of which are several miles long.
They have been formed by the raising, lowering, and sliding of the layers
of sand, or washed out by the stream.

In one of these caverns near Peggau, in Styria, Austria, the skeleton of
a bear (_Ursus Spelaeus_) and the skull of another bear of the same kind
were found, both of which are shown in the annexed cut taken from the
_Illustrirte Zeitung_, the detached skull being placed on a board. The
place in which these bones were found had never been reached before, as
the skeleton was covered by a layer, from four to six inches thick, of
stalagmites, which in turn rested on a layer of pieces or chips of bones
and carbonate of lime, sand, etc. The bones of the skeleton were
scattered over a space about eight square yards, and it required several
days' work to remove the layers from the bones by means of a mallet and
chisel and to give the bones, etc., a presentable appearance.

[Illustration: SKELETON OF A BEAR FOUND IN A CAVE IN STYRIA,
AUSTRIA.]

The skull on the board is of especial interest on account of the
beautiful crystals of calcareous spar, which are from 1/10 to 1/4 of an
inch long, and are formed on the inner sides of the skull. The skull is
5-1/2 in. wide between the fangs and 6-3/5 in. wide at the forehead,
whereas the skull of the skeleton is only 3-9/10 in. wide at the fangs
and 5-1/10 in. wide at the forehead. The skull of the skeleton is 22 in.
long. The small white object on the board supporting the detached skull
represents the skull of an ordinary cat, thus giving an idea of the
enormous size of the bear's skull. The skeleton is 9 ft. 8 in. high, and
is one of the largest and most complete that has been found.

       *       *       *       *       *




THE HARDNESS OF METALS.


The German _Verein zur Bedförderung des Gewerbefleisses_ offers the
following, among other prizes, for essays on technical subjects: One
thousand marks _(£50)_ for a comparative examination of the various
methods hitherto used for determination of the hardness of metals, with
an exposition of their sources of error and limits of accuracy. It is
stated, as a reason for offering the prize, that the methods for making
the required tests are but yet little developed, and that no thorough
comparison has yet been made of the various methods. The hardness of
metals and alloys being a very important factor in several processes, a
really good method of determination is highly desirable. Three thousand
marks (£150) for the best essay on the resistance to pressure of iron
work in buildings, at increased temperatures. It appears that after a
certain fire in a manufactory at Berlin, the police authorities issued
notices concerning the use of cast-iron columns in high buildings, and
that these notices encountered great opposition in many quarters, as it
was considered that neither practice nor theory had yet shown any proof
that cast iron is less trustworthy than wrought iron in cases of fire.

       *       *       *       *       *

A brilliant black varnish for iron, stone, or wood can be made by
thoroughly incorporating ivory black with common shellac varnish. The
mixture should be laid on very thin. But ordinary coal tar varnish will
serve the same purpose in most cases quite as well, and it is not nearly
so expensive.

       *       *       *       *       *




STEAM YACHTS.


Although the racing of steam yachts as a recognized sport has not made
the progress that was at one time expected, yet the owner and crew of a
crack vessel will take as much interest in her performance as those
belonging to a sailing yacht, and hate to be passed quite as badly. In
this way many informal matches come off, and some of these are for
considerable distances. The _Field_ contains a notice of a run recently
made from Plymouth Breakwater to Gibraltar, by the Juno, owned by Mr.
Frank Millan, and the Queen of Palmyra, in which the former beat the
latter by only five minutes. The time occupied was four days twenty
hours, a fair, though not extraordinary, performance for vessels of this
size. The Juno has always been considered a slow boat, but has been much
improved lately by new machinery, which has been put in her by Messrs.
Day, Summers & Co. Her best performance on the run was 235 knots in 21¾
hours. The Marchesa, Mr. C.T. Kettlewell, started from Plymouth on the
23d of last December, and made the run to Gibraltar in four days
seventeen hours; while the Amy, starting on December 12, was four days
thirteen hours from Cowes to Gibraltar.

       *       *       *       *       *


A catalogue, containing brief notices of many important scientific papers
heretofore published in the SUPPLEMENT, may be had gratis at this office.


       *       *       *       *       *




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