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.

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.

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.

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.

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.

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.

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.

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.

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.

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:

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.

SULPHOCYANIDE OF POTASSIUM.

The elements of cyanogen, combined with sulphur, form a salt
radical, sulphocyanogen, C₂NS₂, 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:

Ferrocyanide of Potassium—K₂Cfy+3HO, or
K₂C₈N₃Fe+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(K₂Cfy)+Cl=K₃Cfy₂+KCl.

The radical ferridcyanogen, isomeric² 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 K₃Cfdy.

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
3K₂Cfy + 2(Fe₂O₃3NO₃) =
Fe₄Cfy₃ + 6(KO,NO₅). 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 Fe₃Cfdy, 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.

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.

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.

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.

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.

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.

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.

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.⁵

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:

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:

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:

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.

FIG. 1.

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.

FIG. 3.

FIG. 4.

TABLE.—100 kilogs. Soda Lye containing 20 parts Water
with a corresponding boiling point of 220 deg. Cent. absorb Steam
as follows:

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.

FIG. 5

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
Waldegg⁴ 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.

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.

FIG. 7.

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

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=

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:

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.

—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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

So that—

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.

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?

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.

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!

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!

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 aa 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!

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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