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+*** START OF THE PROJECT GUTENBERG EBOOK 14097 ***
+
+[Illustration]
+
+
+
+
+SCIENTIFIC AMERICAN SUPPLEMENT NO. 483
+
+
+
+
+NEW YORK, APRIL 4, 1885
+
+Scientific American Supplement. Vol. XIX, No. 483.
+
+Scientific American established 1845
+
+Scientific American Supplement, $5 a year.
+
+Scientific American and Supplement, $7 a year.
+
+       *       *       *       *       *
+
+
+TABLE OF CONTENTS.
+
+I.    CHEMISTRY AND METALLURGY.--The Determination of
+      Graphite in Minerals.--By J.B. MACKINTOSH.
+
+      Sulphocyanide of Potassium.
+
+      Sugar Nitro-glycerine.
+
+      On Remelting of Cast Iron.
+
+      The Hardness of Metals.
+
+
+II.   ENGINEERING, ETC.--The Jet Ventilator. 4 figures.
+      Feeding Boilers at the Bottom. 2 figures.
+
+      The Honigmann Fireless Engine.--The fireless working of steam
+      engines by means of a solution of hydrate of soda.--With
+      several figures and diagrams.
+
+      Simple Methods of Calculating Stress in Girders.--By CH. LEAN.--With
+      full page of illustrations.
+
+      A Spring Motor.
+
+      Steam Yachts.
+
+
+III.  TECHNOLOGY.--Foucault's Apparatus for Manufacturing
+      Illuminating Gas and Hydrogen. 2 figures.
+
+      The Circle Divider.
+
+      Soluble Glass.--Process of manufacture.--Use.
+
+      Iron Printing and Microscopic Photography.--Formulas for
+      printing solutions.--Compound negatives.
+
+      Practical Directions for Making Lantern Transparencies.--By
+      T.N. ARMSTRONG.
+
+      Casting Chilled Car Wheels. 6 figures.
+
+
+IV.   ELECTRICITY, ETC.--Electricity and Prestidigitation.
+      2 figures.
+
+      Portable Electric Safety Lamp. 6 figures.
+
+      The Electric Discharge and Spark Photographed Directly without
+      an Objective. 6 engravings.
+
+
+V.    PHYSICS, ETC.--The True Constant of Gravity.
+
+      Origin of Thunder Storms.
+
+      Physics without Apparatus.--Manufacture of illuminating
+      gas.--Elasticity of bodies. 2 figures.
+
+      Scientific Amusements.--Dance of electrified puppets.--Silhouette
+      portraits. 2 figures.
+
+      A Sunshine Recorder. 2 figures.
+
+
+VI.   MEDICINE, HYGIENE, ETC.--How Cholera is Spread.
+
+      Sulphurous Acid and Sulphide of Carbon as Disinfecting
+      Agents.--Methods of burning the same.
+
+
+VII.  MISCELLANEOUS.--Improvised Toys.--With numerous illustrations.
+
+      The Æolian Harp.--Kircher's harp, made in 1558.--Frost and
+      Kastner's harp.--Manner of making the harps. 4 figures.
+
+      How to Break a Cord with the Hands. 1 figure.
+
+      An Aquatic Velocipede for Duck Hunting. 2 engravings.
+
+      Skeleton of a Bear Found in a Cave in Styria, Austria.
+
+
+VIII. BIOGRAPHY.--Theodor Billroth, Prof, of Surgery at Vienna.--With
+      portrait.
+
+       *       *       *       *       *
+
+
+
+
+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.
+
+[Illustration: THEODOR BILLROTH.]
+
+Billroth is a master of surgical technique, and his courage and composure
+increase with the difficulty of the operation. He always makes use of the
+most simple apparatus and instruments, and follows a theoretically
+scientific course which he has never left since he adopted surgery as a
+profession, and by which he has directed surgery into entirely new
+channels. He has given special attention to the study of the healing of
+wounds, the development of swellings and tumors, and the treatment of
+wounds in relation to decomposition and the formation of proud flosh. He
+has had wonderful success in performing plastic operations on the face,
+such as the formation of new noses, lips, etc., from flesh taken from
+other parts of the body or from the face. Although Billroth devoted much
+of his time to the solution of theoretical problems, he has also been
+very successful as an operator. He has removed diseased larynxes,
+performed dangerous goiter operations, and successfully removed parts of
+the oesophagus, stomach, and intestines.
+
+Billroth has been very careful in the selection of his scholars, and many
+of them are now professors of surgery and medicine in Germany, Belgium,
+and Austria. They all honor and admire him, his courage, his character,
+his humane treatment of the sick and suffering, arid his amiability.
+
+The accompanying portrait is from the _Illustrirte Zeitung._
+
+       *       *       *       *       *
+
+
+
+
+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.
+
+[Illustration: FIG. 1.--BURNER FOR SULPHUR.]
+
+The process by combustion of sulphur is the simplest and cheapest. To
+effect such combustion, it suffices to place a piece of iron plate upon
+the floor of the room, and on this to place bricks connected with sand,
+or, what is better, to use a small refractory clay furnace (as advised by
+Mr. Pasteur), of oblong form, 8 inches in width by 10 in length, and
+having small apertures in the sides in order to quicken combustion.
+
+In order to obtain a complete combustion of the flowers of sulphur, it is
+necessary to see to it that the burning is effected equally over its
+entire surface, this being easily brought about by moistening the sulphur
+with alcohol and then setting fire to the latter. Through the use of this
+process a complete and absolute combustion has been obtained of much as
+from 18 to 20 grains of sulphur per cubic foot.
+
+In the proportion of 8 grains to the cubic foot, all the different
+culture broths under experiment were sterilized save the one containing
+the bacteria of charbon. As for the vaccine virus, its properties were
+destroyed. This economical process presents but two inconveniences, viz.,
+the possibility of fire when the furnace is badly constructed, and the
+alteration of such metallic objects as may be in the room. In fact, the
+combustion of sulphur is attended with the projection of a few particles
+of the substance, which form a layer of metallic sulphide upon copper or
+iron objects.
+
+[Illustration: FIG. 2.--CKIANDI BEY'S APPARATUS FOR BURNING CARBON
+SULPHIDE.]
+
+The use of liquid sulphurous acid in siphons does not offer the same
+inconveniences. These siphons contain about one and a half pounds of
+sulphurous acid. The proportion necessary to effect the sterilization of
+the culture broths is one siphon per 706 cubic feet. In such a case the
+_modus operandi_ is as follows: In the middle of the room is placed a
+vessel, which is connected with the exterior by means a rubber tube that
+passes through a hole in the door. After the door has been closed, it is
+only necessary to place the nozzle of the siphon in the rubber tube, and
+to press upon the lever of the siphon valve, to cause the liquid to pass
+from the siphon to the interior of the vessel. The evaporation of the
+liquid sulphurous acid proceeds very rapidly in the free air. This
+process is an exceedingly convenient one; it does away with danger from
+fire, and it leaves the gildings and metallic objects that chance to be
+in the room absolutely intact. Finally, the acid's power of penetration
+appears to be still greater than that which is obtained by the combustion
+of sulphur. It has but one drawback, and that is its high price. Each
+siphon is sold to the public at the price of one dollar. To
+municipalities using sulphurous acid in this form the price would be
+reduced to just one-half that figure.
+
+It will be seen, then, that for a room of 3,530 cubic feet capacity the
+cost would be $5.00 or $2.50.
+
+The combustion of sulphide of carbon furnishes an abundance of sulphurous
+acid, but has hitherto been attended with danger. This, however, has
+recently been overcome by the invention of a new burner by Mr. Ckiandi
+Bey. The general arrangement of this new apparatus is shown in Figs. 2
+and 3.
+
+Mr. Ckiandi's burner consists of an external vessel, A B C D. of tinned
+copper, containing a vessel, I H E F, to the sides of which are fixed
+three siphons, R, S.
+
+[Illustration: FIG. 3.--SECTION OF THE APPARATUS.]
+
+To operate the burner, we place the cylindrical tube, K L M N, in the
+inner vessel, and pour sulphide of carbon into it up to the level _aa_.
+This done, we fill the external vessel with water up to the level _bb_.
+Thanks to the siphons, the water enters the inner vessel, presses the
+sulphide of carbon, which is the heavier, and causes it to rise in the
+tube up to the level _a'a',_ where it saturates a cotton wick, which is
+then lighted. The upper end of the tube is surmounted with a chimney, PQ.
+which quickens the draught.
+
+The combustion may be retarded or quickened at will by causing the level
+_bb_ of the water to rise or lower.
+
+The burner is placed in the room to be disinfected, which, after the wick
+has been lighted, is closed hermetically. When all the sulphide is burned
+it is replaced by water, and the lamp goes out of itself.
+
+The combustion proceeds with great regularity and without any danger. It
+takes about five and a half pounds for a room of 3,500 cubic feet
+capacity. The process is sure and quite economical, since sulphide of
+carbon is sold at about five cents per pound, which amounts to 25 cents
+for a room of 3,500 cubic feet capacity. The burner costs ten dollars,
+but may be used for an almost indefinite period.
+
+The process of producing sulphurous acid by the combustion of sulphide of
+carbon is, as may be seen, very practical and advantageous. It does not
+affect metallic objects, and it furnishes a disinfecting gas
+continuously, slowly, and regularly.
+
+Mr. Ckiandi's burner may also be applied in several industries. It is
+capable of rendering great services in the bleaching of silk and woolen
+goods, and it may also be used for bleaching sponges, straw hats, and a
+number of other objects.--_La Nature_.
+
+       *       *       *       *       *
+
+
+
+
+THE DETERMINATION OF GRAPHITE IN MINERALS.
+
+By J.B. MACKINTOSH.
+
+
+In many instances the accurate determination of the amount of graphite
+present in a rock has proved a rather troublesome problem. The first
+thought which naturally suggests itself is to burn the graphite and weigh
+the carbonic acid produced; but in the case of the sample which led me to
+seek for another method, this way could not be employed, for the specimen
+had been taken from the surface, and was covered and penetrated by
+vegetable growths which could not be entirely removed mechanically. Add
+to this the fact of the presence of iron pyrites and the probable
+occurrence of carbonates in the rock, and it will be at once seen that no
+reliance could be placed on the results obtained by this suggested
+method.
+
+As the problem thus resolved itself into finding a way by which all
+interfering substances could be destroyed without affecting the graphite,
+it at once occurred to me to try the effect of caustic potash. I melted a
+few pieces of potash in a silver crucible until it had stopped spitting
+and was in quiet fusion. I then transferred the weighed sample to the
+crucible, the melted potash in which readily wetted the graphite rock.
+The mass was then gently heated, and occasionally stirred with a piece of
+silver wire. The heat never need be much above the melting point of the
+potash, though toward the last I have been in the habit of raising the
+temperature slightly, to insure the complete decomposition of the melt.
+When the decomposition is complete, which can be known by the complete
+absence of gritty particles, the crucible is cooled and then soaked out
+in cold water. This is very quickly accomplished, and we then see that we
+have an insoluble residue of graphite and a flocculent precipitate of
+lime, magnesia, iron hydrate, etc., while the organic matters have
+disappeared. The sulphides of iron, etc., have given up their sulphur to
+the potash, and everything except the graphite has suffered some change.
+The solution is now filtered through a weighed Gooch crucible, the
+residue washed a few times with water, and then treated with dilute
+hydrochloric acid (followed by ammonia to remove any silver taken up from
+the crucible), which will dissolve all the constituents of the residue
+except the graphite, and after washing will leave the latter free and in
+a condition of great purity.
+
+As evidence of the accuracy of the method, I subjoin the results I
+obtained on a sample whose gangue was free from all organic and other
+impurities, consisting chiefly of quartz:
+
+New Method.       Combustion in Oxygen, Weighing CO_{2}.
+  15.51                         15.54
+
+It is plain that such a result leaves nothing to be desired for the
+accuracy of the method, while, as regards time and trouble, the advantage
+lies on the side of the new method. I have completed a determination in
+less than two hours from the start, and did not hurry myself over it in
+any degree.
+
+Fine pulverization of the sample is not essential, and in fact is rather
+detrimental, as the graphite, when fine, is more difficult to wash
+without loss. When operating on a coarse sample more time is necessarily
+taken, but the resulting graphite shows the manner of occurrence better,
+whether in scales or in the amorphous form.
+
+In consulting the literature bearing on the subject, I cannot find any
+mention of this method employed as an analytical process; it has,
+however, been previously described as a commercial method for the
+purification of graphite,[1] and I understand has been tried on a small
+scale in this country. The method, though inexpensive, yet seems to have
+been abandoned for some reason, and I am not aware that it is now
+employed anywhere.--_Sch. Mines Quarterly._
+
+[Footnote 1: Schloffel, Zeitschrift der K.K. geolog. Reichanstalt, 1866,
+p. 126.]
+
+       *       *       *       *       *
+
+
+
+
+SULPHOCYANIDE OF POTASSIUM.
+
+
+The elements of cyanogen, combined with sulphur, form a salt radical,
+sulphocyanogen, C_{2}NS_{2}, which is expressed by the symbol Csy. The
+sulphocyanide of potassium, KCsy, is prepared by fusing ferrocyanide of
+potassium, deprived of its water of crystallization, intimately mixed
+with half its weight of sulphur and 17 parts of carbonate of potassa. The
+molten mass, after having cooled, is exhausted with water, the solution
+evaporated to dryness, and extracted with alcohol, from which the
+crystals of the salt are separated by evaporation.
+
+It is also made by melting the ferrocyanide of potassium with sulphide of
+potassium. It is a white, crystallizable salt of a taste resembling that
+of niter, soluble in water and alcohol, and extremely poisonous. It
+dissolves the chlorides, iodides, and bromides of silver, is, therefore,
+a fixing agent, but has not come in general use as such. Vogel speaks
+highly of it as an addition to the positive toning bath, although he
+prefers the analogous ammonium salt in the following formula:
+
+Chloride of gold solution.... (1:50) 3 c. cm. (46-1/5 grains).
+Sulphocyanide of ammonium ... 20 grammes (308 grains).
+Water........100 c. cm. (3 ounces 5 drachms 40 grains).
+
+_Ferrocyanide of Potassium_--K_{2}Cfy+3HO, or K_{2}C_{8}N_{3}Fe+3HO, is
+generally known by the name of yellow prussiate of potassa. It contains
+ferrocyanogen, a compound radical, consisting of 1 eq. of metallic iron
+and 3 eq. of the elements of cyanogen, and is designated by the symbol
+Cfy.
+
+The potassium salt is manufactured on a large scale from refuse animal
+matter, as old leather, chips of horn, woolen rags, hoofs, blood (hence
+its German name, "Blutlaugen salz"), greaves, and other substances rich
+in nitrogen, by fusing them with crude carbonate of potassa and iron
+scraps or filings to a red heat, the operation to go on in an iron pot or
+shell, with the exclusion of all air. Cyanide of potassium is generated
+in large quantities. The melted mass is afterward treated with hot water,
+which dissolves the cyanide and other salts, the cyanide being then
+quickly converted by the action of oxide of iron, formed during the
+operation of fusing, into ferrocyanide. The filtered solution is
+evaporated, crystallized, and recrystallized. The best temperature for
+making the solution is between 158 and 176 deg. F. The conversion of the
+cyanide into the ferrocyanide is greatly facilitated by the presence of
+finely divided sulphuret of iron and caustic potash. Some years ago this
+salt was manufactured by a process which dispensed with the use of animal
+matter, the necessary nitrogen being obtained by a current of atmospheric
+air. Fragments of charcoal, impregnated with carbonate of potassa, were
+exposed to a white heat in a clay cylinder, through which a current of
+air was drawn by a suction pump. The process succeeded in a chemical
+sense, but failed on the score of economy.
+
+Richard Brunquell passes ammonia through tubes filled with charcoal, and
+heated to redness so as to form cyanide of ammonium, which is converted
+into the ferrocyanide of potassium by contact with potash solution and
+suitable iron compounds. Ferrocyanide of potassium is in large beautiful
+transparent four-sided tabular crystals, of a lemon-yellow color, soluble
+in four parts of cold and two of boiling water, insoluble in alcohol.
+Exposed to heat it loses three eq. of water, and becomes anhydrous; at a
+high temperature it yields cyanide of potassium, carbide of iron, and
+various gases. This salt is said to have no poisonous properties,
+although the dangerous hydrocyanic acid is made from it. In large doses
+it occasions, however, vertigo, numbness, and coldness. It is used in
+various photographic processes. Newton employs it in combination with
+pyrogallol and soda in the development of bromo-gelatine plates.
+
+The ferri or ferrid cyanide of potassium discovered by Gmelin is often,
+but improperly, termed red prussiate of potash. It is formed by passing a
+current of chlorine gas through a solution of ferrocyanide of potassium
+until the liquid ceases to give a precipitate with a salt of sesquioxide
+of iron, and acquires a deep, reddish-green color. The solution is then
+evaporated, crystallized, and recrystallized. It forms regular prismatic
+or tabular crystals, of a beautiful ruby-red tint, permanent in the air,
+soluble in four parts of cold water. The crystals burn when introduced
+into the flame of a candle, and emit sparks.
+
+The theory of the formation of this salt is, that one eq. of chlorine
+withdraws from two eq. of the ferrocyanide of potassium, one eq. of
+potassium, forming chloride of potassium, which remains in the mother
+liquid. The reaction is explained by the following equation:
+2(K_{2}Cfy)+Cl=K_{3}Cfy_{2}+KCl.
+
+The radical ferridcyanogen, isomeric[2] with ferrocyanogen, is supposed
+to be formed by the coalescence of two equivalents of ferrocyanogen, and
+is represented by the symbol Cfdy; accordingly the formula of
+ferridcyanide of potassium is K_{3}Cfdy.
+
+[Footnote 2: Isomeric bodies, or substances different in properties yet
+identical in composition, are of constant occurrence in organic
+chemistry, and stand among its most peculiar features.]
+
+Ferridcyanide of potassium has found extensive application in
+photographic processes for intensifying negatives; those of Eder, in
+combination with nitrate of lead, or Selle's, with nitrate of uranium;
+Ander's blue intensification of gelatine negatives, Farmer's process of
+reducing intensity, the coloring of diapositives, the very important blue
+printing, and various others, are daily practiced in our laboratories.
+
+The ferrocyanide of potassium is a chemical reagent of great value,
+giving rise to precipitates with the neutral or slightly acid solutions
+of metals, like the beautiful brown ferrocyanide of copper, and that of
+lead. When a ferrocyanide is added to a solution of a sesquioxide of
+iron, Prussian blue or ferrocyanide of iron is produced. The exact
+composition of this remarkable substance is not distinctly stated, as
+various blue compounds may be precipitated under different circumstances.
+Berzelius gives the following account: 3 eq. of ferrocyanide and 2 eq. of
+sesquioxide of iron are mutually decomposed, forming 1 eq. of Prussian
+blue and 6 eq. of the potassa salt, which remains in solution, or
+3K_{2}Cfy + 2(Fe_{2}O_{3}3NO_{3}) = Fe_{4}Cfy_{3} + 6(KO,NO_{5}). It
+forms a bulky precipitate of an intense blue, is quite insoluble in water
+or weak acids, with the exception of oxalic acid, with which it gives a
+deep blue liquid, occasionally used as blue ink.
+
+Ferridcyanide of potassium, added to a salt of the sesquioxide of iron,
+yields no precipitate, but merely darkens the reddish-brown solution;
+with protoxide of iron it gives a blue precipitate, containing
+Fe_{3}Cfdy, which is of a brighter tint than that of Prussian blue, and
+is known by the name of Turnbull's blue. Hence, the ferridcyanide of
+potassium is as excellent a test for protoxide of iron as the yellow
+ferrocyanide is for the sesquioxide.--_E., Photo. Times_.
+
+       *       *       *       *       *
+
+
+
+
+FOUCAULT'S APPARATUS FOR MANUFACTURING ILLUMINATING GAS AND
+HYDROGEN.
+
+
+The illuminating gas and hydrogen apparatus, illustrated herewith, is
+adapted to all cases in which it is desirable to manufacture gas upon a
+small scale.
+
+Through the use solely of oil or water, it produces illuminating gas or
+pure hydrogen for all the applications that may be required of them. It
+consists of three parts, viz., of a vaporizer, A, which converts the
+liquids into gas; of a distributer, B, which contains and distributes the
+liquids to be converted into gas, and of a regulator, C, which
+automatically regulates the flow of the liquids in proportion as they are
+used.
+
+[Illustration: FIG. 1.--FOUCAULT'S GAS APPARATUS.]
+
+In the vaporizer Mr. Foucault, the inventor of the apparatus, obtains a
+perfectly regular combustion through the use of a central column, 15,
+charged with fuel, closed at the upper part, open beneath, and entering a
+furnace that is fed by it with regularity, the zone of combustion not
+being able to extend beyond the level of the draught. The grate, 16, is
+capable of revolving upon its axis in order to separate the cinders. It
+also oscillates, and is provided with jaws for crushing the fuel; and it
+may likewise be lowered so as to let the fire drop into the ash-pan when
+it is desired to stop operations.
+
+The vaporizer, properly so called, is not placed directly over the fire,
+and for this reason the production of a spheroidal state of the liquid is
+avoided. It consists of a vessel, 44, into which the liquid is led by a
+pipe, 43. The cast-iron evaporating vessel, 14, is provided with
+appendages, 14 _bis_, which dip into the liquid and bring about its
+evaporation. A refractory clay sleeve, 41, protects the lower part of the
+cylinder, 15, from the fire, and diminishes the smoke passages at 42. The
+vapor produced makes its way vertically through a layer of charcoal
+placed between the evaporating vessel, 14, and the receiver, 17, and
+serving to decompose the aqueous vapor formed.
+
+All clay and red and white lead joints are done away with in this part of
+the apparatus, as are also packing bolts. Thus, at the upper part the
+cover, 19, is provided with a rim that enters a cavity filled with lead,
+so, too, the lower part of the evaporating vessel, 14, rests in a channel
+containing lead. There is also at 30, a joint of the same character for
+the rim of the external cylindrical vessel, 18. Both this latter and the
+receiver, 17, dip beneath into a tank of water, 66.
+
+The distributer, B, is so arranged as to cause the water, and oil, and
+the liquids to be vaporized to flow with the greatest regularity, and
+proportionally to the consumption of the gas in cases where the latter is
+not stored up in a gas meter. The flow is controlled by cocks that are
+actuated by variations in the height of the regulator receiver. All the
+condensation that occurs in the various parts of the apparatus collects
+in a receptacle, 52, so arranged as to perform the office of a separator
+and set apart the oil at 20, and the water at 21, through the natural
+effect of their difference in density. This latter is likewise utilized
+for causing the oil to flow into the vaporizer through 26 and 27, instead
+of using a graduated cock that receives a variable pressure from the
+receiver. In this way every cause of obstruction is avoided.
+
+[Illustration: FIG. 2.--SECTION.]
+
+We have stated that the regulator, C, serves to automatically regulate
+the flow of the liquids proportionally to the consumption of the gases
+produced. To effect this a communication is established between the
+regulator receiver, 59, and the aperture through which the liquids flow,
+and the flow is thus modified by the valves, 54 and 55.
+
+The water contained in the reservoir of the regulator serves to wash the
+gas which enters through a number of orifices in the disk, 60, this
+latter being fixed beneath the level of the water. The gas may be
+purified by dissolving metallic salts in the water.
+
+By means of the arrangement above described, there may be manufactured at
+will a rich gas from liquid hydrocarburets, hydrogen from water, and gas
+obtained by an admixture of two others simultaneously produced and
+combined in the apparatus.--_Chronique Industrielle._
+
+       *       *       *       *       *
+
+
+
+
+SUGAR NITRO-GLYCERINE.
+
+
+A new explosive has been discovered by M. Roca, a French engineer, who
+communicates an account of it to _Le Génie Civil_. The discovery was due
+entirely to scientific induction from some experiments made upon
+different specimens of dynamite, with a view to the determination of the
+effect on the explosive force of the various inert or at least slowly
+combustible substances with which nitro-glycerine is mixed to produce the
+dynamite of commerce. Of late, in place of the infusorial earth which
+formed the solid portion of Nobel's dynamite, such substances as sawdust,
+powdered bark, and even gunpowder, have been used, probably for the sake
+of economy alone, without, except in the latter case, any reference to
+the influence which they might have upon the combustion of the
+nitro-glycerine; but M. Roca, in testing a variety of samples, was struck
+by the difference among them in regard to energy of explosion, and
+discovered that if a portion of free carbon, sufficient to combine with
+the oxygen disengaged from the nitro-glycerine, was present at the moment
+of detonation, the effect was greater than where, as in the case of
+gunpowder, the solid portion alone furnished oxygen enough to burn all
+the free carbon, without calling upon the nitro-glycerine for any. In
+fact, it appeared from experiment that the dose of carbon might with
+advantage be so great as not only to be itself oxidized into carbonic
+oxide by the oxygen of the nitro-glycerine, but to reduce the carbonic
+acid developed by the explosion of the latter itself into carbonic oxide.
+The limit of the advantageous effect of free carbon ceased here, and if
+more were added to the mixture, the cavities formed by the explosion in
+the lead cubes used for test were found simply lined with soot; but up to
+the limit necessary for converting all the carbon in the dynamite into
+carbonic oxide, the addition of a reducing agent was shown to be an
+important gain. This was confirmed by theory, which shows that pure
+nitro-glycerine, which is composed of six parts of carbon and two of
+hydrogen, combined with three times as much nitric acid and water,
+decomposes on explosion into six parts of carbonic acid, five of watery
+vapor, one of oxygen, and three of nitrogen, while the addition of seven
+more parts of free carbon to the mixture causes the development, by
+explosion, of thirteen volumes of carbonic oxide, five parts of watery
+vapor, and three of nitrogen, or twenty-one volumes of gas in place of
+fifteen. As the power of an explosive depends principally on the amount
+of gas which results from its sudden combustion, it was evident that the
+addition of pure or nearly pure carbon, in a condition to be readily
+combined with the other elements, ought to increase materially the force
+of nitro-glycerine, and M. Roca experimented accordingly with an
+admixture of sugar, as a highly carbonized body immediately available,
+and found that three parts of this, mixed with seven parts of
+nitro-glycerine, detonated with a force from thirty to thirty-five per
+cent. greater than that of pure nitro-glycerine. Many other organic
+carbonaceous substances may be employed in place of sugar, with various
+advantages. In comparing these simple compounds with the celebrated
+explosive gum, prepared by dissolving gun-cotton in nitro-glycerine, it
+is found that the latter is far inferior, having an energy very little
+superior to that of pure nitro-glycerine.
+
+       *       *       *       *       *
+
+
+
+
+THE CIRCLE-DIVIDER.
+
+
+This little apparatus, invented by Prof. Mora, of Senlis, permits of
+dividing circumferences or circles into equal or proportional parts. It
+consists (Fig. 2) of a rule, A, divided into equal or proportional parts,
+which pivots in the manner of a compass around a rod, T, that serves as a
+central rotary point. Along this rule moves a slide, R, provided with an
+aperture, C, which is made to coincide with one of the divisions. This
+division corresponds to the number of equal or proportional parts into
+which the circle is to be divided. The slide is provided with a wheel, E,
+that carries a point which serves at every revolution to trace the points
+that indicate the divisions of the circumference.
+
+[Illustration: FIG. 1.--MODE OF USING THE CIRCLE DIVIDER. ]
+
+The apparatus operates as follows: Suppose, for example, that it becomes
+necessary to divide a circumference into 19 equal parts: We make the
+aperture, C, coincide with the 19th division of the rule, and fix the
+point of the rod, T, in the center of the circumference, and cause the
+rule to revolve around it. The wheel, E, will revolve upon its axis, g,
+and, at every revolution, its point will make a mark which corresponds to
+the 19th part of the circumference--
+
+Circumf. c / Circumf. C = r / R
+
+It is always necessary that the extremity of the wheel, E, and the
+center-point, T, shall be at the same height in order to have the
+divisions very accurate.
+
+[Illustration: FIG. 2.--THE CIRCLE DIVIDER. ]
+
+       *       *       *       *       *
+
+
+
+
+SOLUBLE GLASS.
+
+
+Although the manufacture of soluble glass does not strictly belong to the
+glass maker's art, yet it is an allied process to that of manufacturing
+glass. Of late soluble glass has been used with good effect as a
+preservative coating for stones, a fire-proofing solution for wood and
+textile fabrics. Very thin gauze dipped in a solution of silicate of
+potash diluted with water, and dried, burns without flame, blackens, and
+carbonizes as if it were heated in a retort without contact of air. As a
+fire-proofing material it would be excellent were it not that the
+alkaline reaction of this glass very often changes the coloring matters
+of paintings and textile fabrics. Since soluble glass always remains
+somewhat deliquescent, even though the fabrics may have been thoroughly
+dried, the moisture of the atmosphere is attracted, and the goods remain
+damp. This is the reason why its use has been abandoned for preserving
+theater decorations and wearing apparel. Another application of soluble
+glass has been made by surgeons for forming a protecting coat of silicate
+around broken limbs as a substitute for plaster, starch, or dextrine.
+
+The only use where soluble glass has met with success is in the
+preservation of porous stones, building materials, paintings in
+distemper, and painting on glass. Before we describe these applications,
+we will give the processes used in making soluble glass.
+
+The following ingredients are heated in a reverberatory furnace until
+fusion becomes quieted: 1,260 pounds white sand, 660 pounds potash of
+78°. This will produce 1,690 pounds of transparent, homogeneous glass,
+with a slight tinge of amber. This glass is but little soluble in hot
+water. To dissolve it, the broken fragments are introduced into a iron
+digester charged with a sufficient quantity of water, at a high pressure,
+to make a solution marking 33° to 35° Baume. Distilled or rain water
+should be used, as the calcareous salts contained in ordinary water would
+produce insoluble salts of lime, which would render the solution turbid
+and opalescent; this solution contains silica and potash combined
+together in the proportion of 70 to 30.
+
+Silicate of soda is made with 180 parts of sand, 100 parts carbonate of
+soda (0.91), and is to be melted in the same manner as indicated
+previously.
+
+Soluble glass may also be prepared by the following method: A mixture of
+sand with a solution of caustic potash or soda is introduced into an iron
+boiler, under 5 or 6 atmospheres of pressure, and heated for a few hours.
+The iron boiler contains an agitator, which is occasionally operated
+during the melting. The liquid is allowed to cool until it reaches 212°,
+and is drawn out after it has been allowed to clear by settling; it is
+then concentrated until it reaches a density of 1.25, or it may be
+evaporated to dryness in an iron kettle. The metal is not affected by
+alkaline liquors.
+
+The glass is soluble in boiling water; cold water dissolves but little of
+it. The solution is decomposed by all acids, even by carbonic acid.
+Soluble glass is apparently coagulated by the addition of an alkaline
+salt; mixed with powdered matters upon which alkalies have no effect, it
+becomes sticky and agglutinative, a sort of mineral glue.
+
+To apply soluble glass for the preservation of buildings and monuments of
+porous materials, take a solution of silicate of potash of 35° Baume,
+dilute it with twice its weight of water, paint with a brush, or inject
+with a pump; give several coats. Experience has shown that three coats
+applied on three successive days are sufficient to preserve the materials
+indefinitely, at a cost of about 15 cents per square yard. When applied
+upon old materials, it is necessary to wash them thoroughly with water.
+The degree of concentration of the solutions to be used varies with the
+materials. For hard stones, such as sand and free stones, rock, etc., the
+solution should mark 7° to 9° Baume; for soft stones with coarse grit, 5°
+to 7°; for calcareous stones of soft texture, 6° to 7°. The last coating
+should always be applied with a more dilute solution of 3° to 4° only.
+
+Authorities are divided upon the successful results of the preservation
+of stone by silicates. Some claim in the affirmative that the protection
+is permanent, while others assert that with time and the humidity of the
+atmosphere the beneficial effects gradually disappear. It might be worth
+while to experiment upon some of the porous sandstones, which, under the
+extreme influence of our climate, rapidly deteriorate; such, for
+instance, as the Connecticut sandstone, so popular at one time as a
+building material, but which is now generally discarded, owing to its
+tendency to crumble to pieces when exposed to the weather even for a few
+years.
+
+Soluble glass has also been used in Germany to a great extent for mural
+painting, known as stereochromy. The process consists in first laying a
+ground with a lime water; when this is thoroughly dry, it is soaked with
+a solution of silicate of soda. When this has completely solidified, the
+upper coating is applied to the thickness of about one-sixteenth of an
+inch, and should be put on very evenly. It is then rubbed with fine
+sandstone to roughen the surface. When thoroughly dry, the colors are
+applied with water; the wall is also frequently sprinkled with water. The
+colors are now set by using a mixture of silicate of potash completely
+saturated with silica, with a basic silicate of soda (a flint liquor with
+soda base, obtained by melting 2 parts sand with 3 parts of carbonate of
+soda). As the colors applied do not stand the action of the brush, the
+soluble glass is projected against the wall by means of a spray. After a
+few days the walls should be washed with alcohol to remove the dust and
+alkali liberated.
+
+The colors used for this style of painting are zinc white, green oxide
+of chrome, cobalt green, chromate of lead, colcothar, ochers, and
+ultramarine.
+
+Soluble glass has also been used in the manufacture of soaps made with
+palm and cocoanut oil; this body renders them more alkaline and harder.
+
+Interesting experiments have been made with soluble glass for coloring
+corals and shells. By plunging silicated shells into hot solutions of
+salts of chrome, nickel, cobalt, or copper, beautiful dyes in yellow,
+green, and blue are produced. Here seems to be a field for further
+application of this discovery.
+
+Soluble glass has also been applied to painting on glass in imitation of
+glass staining. By using sulphate of baryta, ultramarine, oxide of
+chrome, etc., mixed with silicate of potash, fast colors are obtained
+similar to the semi-transparent colors of painted windows. By this means
+a variety of cheap painted glass may be made. Should these colors be
+fired in a furnace, enameled surfaces would be produced. As a substitute
+for albumen for fixing colors in calico printing, soluble glass has been
+used with a certain degree of success; also as a sizing for thread
+previous to weaving textile fabrics. Thus it would seem that this
+substance has been used for many purposes, but since its application does
+not seem to have been extended to any great degree, the defects here
+pointed out in its use as a fire-proofing material perhaps also exist, to
+a certain degree, in its other applications. In painting upon glass, for
+instance, it is asserted that the brilliancy and finish of ordinary
+vitrified colors cannot be obtained.--_Glassware Reporter._
+
+       *       *       *       *       *
+
+
+
+
+THE JET VENTILATOR.
+
+
+[Illustration: KORTING'S JET VENTILATOR.]
+
+Messrs. Korting bros., of London, induced by the interest that has been
+directed to the separate ventilation of mines in which fire-damp is apt
+to form, have adopted for this purpose their jet ventilator. The
+instrument, which we illustrate in Fig. 1, has been, we understand,
+considerable simplified, and adapted for the special object in view. The
+ventilators are worked by compressed air, and are so arranged that,
+without stopping their action, the quantity of air they deliver can be
+rapidly increased or diminished. This ample power of control has been
+arranged for by the special wish of the mining authorities, who wish to
+regulate the ventilation according to the development of fire-damp or the
+greater or less number of men at work. Under circumstances of this kind
+the quantity of air taken into the mine can be changed instantly. The
+illustrations, Figs. 2, 3, and 4, show different modes of fixing the jet
+ventilator. In Fig. 2, it is arranged to blow the air forward; in Fig. 3,
+it is shown exhausting the air; and in Fig. 4, it is represented as
+exhausting and blowing simultaneously, the efficiency in each case being
+always the same. Any bends in the conduit affect the result to a very
+slight degree, and the ventilator may be used with advantage when the
+conduit is divided as in Fig. 4, in order to get the fresh air to
+different points. The ventilators are easily fixed to the air conduits.
+If they are to be connected to zinc air pipes, the pipe is simply slipped
+over the point, L. in Fig. 1, and if to wooden conduits the apparatus is
+simply put into them, and if no other support is required. Furthermore,
+they are so light that it suffices for one man to fix them or change
+their position.
+
+Messrs. Korting Bros. advance the following claims for this mode of
+ventilating mines: Certainty of action, no moving parts whatever,
+and, consequently, no need of lubrication; no need of attention.
+--_Mech. World_.
+
+
+       *       *       *       *       *
+
+
+
+
+ON REMELTING OF CAST IRON.
+
+
+From trials conducted by Ledebur, it appears that cast iron is rendered
+suitable for foundry purposes--i.e., to fill the moulds well and to yield
+sharp and definite forms free of flaws, to be cut with a chisel, and
+turned on a lathe--through a certain percentage of graphite, whose
+presence depends on that of carbon and silicium. Cast iron free of
+silicium yields on cooling the entire amount of carbon in the amorphous
+state, while presence of the former metal gives rise to the formation of
+graphite, and, consequently, causes a partial separation of carbon. Iron
+suffers on casting loss of graphite, assumes a finely-grained texture,
+becomes hard and brittle, and is changed from gray to white. In view of
+the fact that samples of cast iron with equal percentage of silicium and
+carbon yield on casting a different product, it has become necessary to
+institute experiments as to the cause of this behavior. Samples of cast
+iron were therefore repeatedly melted, and thin sections of each melt
+examined; these sections exhibited a gray color, though less apparent
+than in the unmelted sample, and possessed sufficient softness to admit
+boring and filing. During these processes of fusing, the amount of
+silicium, carbon, and manganese had been gradually decreased, and
+amounted to 12.7, 17.6, and 24.4 per centum for silicium in the three
+samples examined. It also was observed that the more manganese the iron
+contains the less readily the percentage of silicium is diminished; and
+since manganese is more subject to oxidation than silicium, it is capable
+to reduce silicic acid of the slag or lining to metal, and thus to
+augment the amount of silicium in cast iron. The percentage of carbon
+also suffers diminution by oxidation, which latter process is impeded by
+presence of manganese, a fact of some importance in melting of cast iron
+in the cupola furnace. An excess of manganese renders cast iron hard and
+brittle, and imparts to it the properties to absorb gases, while an
+amount of 1.5 per centum, as found in Scotch iron, undoubtedly has the
+effect to produce those properties for which this iron is held in high
+repute. The amount of copper is not visibly altered by fusion, but that
+of phosphorus and sulphur slowly increased.
+
+Experiments in regard to the relation between chemical composition and
+strength of the material have established that a large amount of
+silicium, graphite, manganese, and combined carbon reduce the elasticity,
+strength, and tenacity of cast iron, and that a limited percentage of
+silicium counteracts the injurious influence produced by an excess of
+combined carbon. On remelting of cast iron, increase in tensile strength
+was observed, which attained its maximum in iron with a small percentage
+of silicium after the third, and in such with a large amount after the
+fourth melting. The increase in tensile strength was accompanied by a
+loss of silicium, graphite, and manganese coupled with a simultaneous
+augmentation of combined carbon. A fifth melting of the cast iron renders
+it hard, brittle, and white, through oxidation of silicium and subsequent
+lowering of the amount of carbon. On lessening the percentage of combined
+carbon with formation of graphite the injurious influence of the
+accessorial constituents of cast iron is diminished, especially that
+produced by the presence of phosphorus.--_Eisenhuettentechnik._
+
+       *       *       *       *       *
+
+
+
+
+FEEDING BOILERS AT THE BOTTOM.
+
+
+One of the most important things to be considered in boiler construction
+is the position and arrangement of the feed apparatus, but it is,
+unfortunately, one of the elements that is most often overlooked, or, if
+considered at all, only in a very superficial manner. Many seem to think
+that it is only necessary to have a hole somewhere in the boiler--no
+matter what part--through which water may be pumped, and we have all that
+is desired. This is a very grave error. Many boilers have been ruined,
+and (we make the assertion with the confidence born of long experience) a
+large number of destructive explosions have been directly caused by
+introducing the feed water into boilers at the wrong point.
+
+On the location and construction of the feed depends to some extent the
+economical working of a boiler, and, to a great extent, especially with
+certain types of boilers, its safety, durability, and freedom from a
+variety of defects, such as leaky seams, fractured plates, and others of
+a similar kind. And it is unfortunately true that the type of boiler
+which from its nature is most severely affected by mal-construction, such
+as we are now speaking of, is the very one which is the oftenest subject
+to it. We are speaking now more particularly of the plain cylinder
+boiler, of which there are many in use throughout the country.
+
+Plain cylinder boilers are, as a rule, provided with mud drums located
+near the back end. As a rule, also, these boilers are set in pairs over a
+single furnace, and the mud drum extends across beneath, and is connected
+to both, and one end projects through the setting wall at the side. Our
+illustrations show a typical arrangement of this kind. Fig. 1 shows a
+transverse section of the boilers and setting, while Fig. 2 shows a
+longitudinal section of the same. It is a favorite method to connect the
+feed pipe, F, to the end of the mud drum which projects through the wall,
+and here the feed water is introduced, whether hot or cold; and there is
+really not so much difference after all between the two, for no matter
+_how_ effective a heater may be, the temperature to which it can raise
+water passing through is quite low compared with the temperature of the
+water in the boiler due to a steam pressure of say eighty pounds per
+square inch. The difference in the effect produced by feeding hot or cold
+water at the wrong place is one of degree, not of kind.
+
+When a boiler is under steam of say eighty pounds per square inch, the
+body of water in it will have a temperature of about 324 degrees Fahr.,
+and the shell plates will necessarily be somewhat hotter, especially on
+the bottom (just _how_ much hotter will depend entirely upon the quantity
+of scale or sediment present). Now introduce a large volume of cold water
+through an opening in the bottom, and what becomes of it? Does it rise at
+once, and become mixed with the large body of water in the boiler? By no
+means. It _cannot_ rise until it has become heated, for there is a great
+difference between the specific gravity of water at 60°, or even 212°
+Fahr., and water at 324°. Consequently, it "hugs" the bottom of the
+boiler, and flows toward the _front_ end, or hottest portion of the
+shell. Now let us examine the effect which it produces.
+
+We know that wrought iron expands or contracts about 1 part in 150,000
+for each degree that its temperature is raised or lowered. This is
+equivalent to a stress of _one ton_ per square inch of section for every
+15 degrees. That is, suppose we fix a piece of iron, a strip of
+boilerplate, for instance, ¼ of an inch thick and 4 inches wide, at a
+temperature of 92 degrees Fahr., between a pair of immovable clamps.
+Then, if we reduce the temperature of the bar under experiment to that of
+melting ice, we put a stress of four tons upon it, or one ton for each
+inch of its width.
+
+[Illustration: FIG. 1]
+
+Now this is precisely what happens when cold water is fed into the bottom
+of a boiler. We have the plates of the shell at a temperature of not
+less, probably, than 350° Fahr. A large quantity of cold water, often at
+a temperature as low as 50° Fahr., is introduced through an opening in
+the bottom, and flows along over these heated plates. If it could produce
+its _full_ effect at once, the contraction caused thereby would bring a
+stress of 300 ÷ 15 = 20 tons per square inch upon the bottom plates of
+the shell. But fortunately it cannot exert its full effect at once, but
+it _can_ act to such an extent that we have known it to rupture the
+plates of a new boiler through the seams on the bottom _no less than
+three times in less than six weeks_ after the boilers were started up.
+
+The effect in such cases will always be the most marked, especially if
+the plant is furnished with a heater, when the engine is not running, for
+then, as no steam is being drawn from the boilers, there is comparatively
+little circulation going on in the water in the boiler, and the water
+pumped in, colder than usual from the fact that the heater is not in
+operation, spreads out in a thin layer on the lowest point of the shell,
+and _stays there_, and keeps the temperature of the shell down, owing to
+the fires being banked or the draught shut, while the larger body of
+water above, at a temperature of from 300 to 325 degrees, keeps the upper
+portion of the shell at _its_ higher temperature. It will readily be seen
+that the strain brought upon the seams along the bottom is something
+enormous, and we can understand why it is that many boilers of this class
+rupture their girth seams while being filled up for the night after the
+engine has been shut down. To most persons who have but a slight
+knowledge of the matter, we fancy it would be a surprise to see the
+persistence with which cold water will "hug" the bottom of a boiler under
+such circumstances. We have seen boilers when the fire has been drawn,
+and cold water pumped in to cool them off, so cold on the bottom that
+they felt cold to the touch, and must consequently have had a temperature
+considerably below 100° Fahr., while the water on top, above the tubes,
+was sufficiently hot to scald; and they will remain in such a condition
+for hours.
+
+[Illustration: FIG. 2.]
+
+The only thing to be done, where feed connections are made in the manner
+described, is to change them, and by changing them at once much trouble,
+or even a disastrous explosion, may be avoided. Put the feedpipe in
+through the front head, at the point marked _p_ in Fig. 1, drill and tap
+a hole the proper size for the feed pipe, cut a long thread on the end of
+the pipe, and screw the pipe through the head, letting it project through
+on the inside far enough to put on a coupling, then screw into the
+coupling a piece of pipe not less than eight or ten feet long, letting it
+run horizontally toward the back end of the boiler, the whole arrangement
+being only from 3 to 4 inches below the water line of the boiler, and hot
+or cold water may be fed indifferently, without fear of danger from
+ruptured plates or leaky seams. In short, put in a "top feed," and avoid
+further trouble.--_The Locomotive_.
+
+       *       *       *       *       *
+
+
+
+
+[MICROSCOPICAL JOURNAL.]
+
+IRON PRINTING AND MICROSCOPIC PHOTOGRAPHY.
+
+By C.M. VORCE, F.R.M.S.
+
+
+I. FORMULAS FOR PRINTING SOLUTIONS.
+
+_Blue Prints_.--The best formula for this process, of many that I have
+tried, is that furnished by Prof. C.H. Kain, of Camden, N.J., in which
+the quantity of ammonio-citrate of iron is exactly double that of the red
+prussiate of potash, and the solutions strong. This gives strong prints
+of a bright dark blue, and prints very quickly in clear sunlight.
+
+Dissolve six grains of red prussiate of potash in one drm. of distilled
+water; in another drm. of distilled water dissolve twelve grains of
+ammonio-citrate of iron. Mix the two solutions in a cup or saucer, and at
+once brush over the surface of clean strong paper. Cover the surface
+thoroughly, but apply no more than the paper will take up at once; it
+should become limp and moist, but not wet. The above quantity of
+solution, two drms., will suffice to sensitize ten square feet of paper,
+or three sheets of the "regular" size of plain paper, 18×22. As fast as
+the sheets are washed over with the solution, hang them up to dry by one
+corner. The surplus fluid will collect in a drop at the lower corner, and
+can be blotted off.
+
+_Black Prints_.--Wash the paper with a saturated solution of bichromate
+of potash, made quite acid with acetic acid. After printing, wash the
+prints in running water for twenty to thirty minutes, then float them
+face down on a weak solution (five to ten per cent.) of protosulphate of
+iron for five minutes, and wash as before. If preferred, the iron
+solution may be washed over the prints, or they may be immersed in it,
+but floating seems preferable. After the second washing, wash the prints
+over with a strong solution of pyrogallic acid, when the print will
+develop black, and the ground, if the washings were sufficient, will
+remain white. A final washing completes the process.
+
+If a solution of yellow prussiate of potash be used in place of the pyro
+solution, a blue print is obtained. Bichromate prints can be made on
+albumenized paper by floating it on the solution, and by using a
+saturated solution of protosulphate of iron and a saturated solution of
+gallic acid. Very fine prints can be so produced nearly equal to silver
+prints, and at somewhat less cost, but with a little or no saving of time
+or labor.
+
+_Chief Proof Solution_.--If old oxalate developer be exposed in a shallow
+vessel in a warm place, a deposit of light green crystals will be formed,
+composed of an impure oxalate of iron. If these crystals be dissolved in
+water, and paper washed with a strong solution, when dry it may be
+exposed in the printing-frame, giving full time. The image is very faint,
+but on washing in or floating on a moderately strong solution of red
+prussiate of potash for a minute or less, a blue positive is produced,
+which is washed in water as usual to fix it. The unused developer
+produces the best crystals for the purpose, and the pure ammonio-oxalate
+is vastly better than either.
+
+All of the above operations, except the printing, should be carried on in
+the dark room, or by lamp or gas light only. The solutions and the paper
+should also be kept in the dark, and prepared as short a time as possible
+before use.
+
+
+II. COMPOUND NEGATIVES.
+
+In photographing with the microscope, it frequently occurs that the
+operator, instead of devoting a negative to each of two or more similar
+objects for comparison, printing both upon the same print, prefers to
+have the whole series upon one negative, and taking from this a single
+print. There is often room for two or more images upon the same plate. If
+the center of the plate is devoted to one, obviously no more can be
+accommodated on it, but by placing one at each end, or one on each
+quarter of the plate, both economy of plates and convenience of printing
+are secured. The end may be readily accomplished by matting the plate as
+a negative is matted in printing.
+
+Suppose it be desired to photograph four different species of acari on
+one plate, the image of each when magnified to the desired extent only
+covering about one-fourth the exposed area of the plate. First, a mat is
+prepared of card-board or thick non-actinic paper, which is adjusted to
+exactly fill the opening of the plate holder, lying in front of and close
+against the plate when exposed, and having one-quarter very exactly cut
+out. A convenient way to fit this mat is to leave projecting lugs on each
+side at exactly the same distance from the ends, and cut notches in the
+plate-holder into which the lugs may closely fit. If this work is
+carefully done, the mat may be reversed both sidewise and endwise, and
+the lugs will fit the notches; if so, it is ready for use. The object
+being focused upon the focusing glass or card, the camera is raised
+one-half the vertical dimension of the plate and displaced to one side
+half the horizontal dimension, when the image will be found to occupy
+one-quarter of the plate. The mat being placed in the plate holder, a
+focusing glass is inserted in the position the plate will occupy, and
+final adjustment and focusing made. The plate is then marked on one
+corner on the film side with a lead pencil, placed in the holder without
+disturbing the mat, and the exposure made. When the plate is replaced for
+a second exposure, either the mat is reversed or the plate turned end for
+end; but it is best to always place the plate in the holder in the same
+position and change the mat to expose successive quarters, but this
+requires the camera to be moved for each exposure.
+
+With similar objects, and some judgment in making two exposures,
+negatives may be made with almost exactly the same density in each
+quarter, and by cutting out slightly less than one-quarter of the mat the
+four images will be separated by black lines in the print; by cutting out
+a trifle more than the exact quarter, they will be separated by white
+lines instead of black.
+
+       *       *       *       *       *
+
+
+
+
+PRACTICAL DIRECTIONS FOR MAKING LANTERN TRANSPARENCIES.
+
+[Footnote: Abstract of a paper communicated to the Glasgow and West of
+Scotland Amateur Photographic Association.--From the _Photographic
+News_.]
+
+By T.N. ARMSTRONG.
+
+
+When the season for out-door work closes, amateurs begin to look about
+for means of employment during the dark evenings. There is, fortunately,
+no necessity for being idle, or to relinquish photographic pursuits
+entirely, even though the weather and light combine to render out-door
+work almost impracticable; and most amateurs will be found to have some
+hobby or favorite amusement which enables them to keep in practice during
+those months when many channels of employment are closed to them; and
+probably one of the most popular as well as the most pleasing occupations
+is the production of transparencies for the lantern.
+
+It is not my desire to enter into any discussion as to this or that being
+the best means of producing these delightful pictures, but merely to
+describe a way by which a pleasant evening can be spent at photography,
+and slides produced of much excellence by artificial light.
+
+To-night I propose, by the aid of artificial light, to make a few slides
+with Beechy's dry plates. On the whole, I have been most successful with
+them, and have obtained results more satisfactory than by any of the
+other processes I have tried. I do not say that results quite as good
+cannot be obtained by any other method, for I know manipulative skill
+plays a most important part in this class of work.
+
+When I first took up the making of transparencies with wet collodion, I
+was told that my sorrows would not be far to seek, and so I soon found
+out. Need I tell you of all my failures, such as films floating off the
+glass, oyster-shell markings, pin-holes, films splitting when dry, etc.,
+etc., not to speak of going to business with fingers in fearful state
+with nitrate of silver and iron developer? Now all these miseries have
+gone, and I can, with dry collodion plates, work with the greatest of
+comfort, and obtain results quite equal to the best products of any
+method.
+
+It may be interesting to some to know the formula by which the emulsion
+is made, and as the making of it is by no means a difficult operation, I
+may be pardoned if, before going fully into the more practical part of my
+paper, I describe the formula, and also the manner in which I coat and
+dry the plates. The formula is as follows, for which the world is
+indebted to Canon Beechy:
+
+In 8 ounces of absolute alcohol dissolve 5 drachms of anhydrous bromide
+of cadmium. The solution will be milky. Let it stand at least twenty-four
+hours, or until perfectly clear; it will deposit a white powder. Decant
+carefully into an 8-ounce bottle, and add to it a drachm of strong
+hydrochloric acid. Label this "bromide solution;" and it is well to add
+on the label the constituents, which will be found to be nearly:
+
+ Alcohol.              1 ounce.
+ Bromide of cadmium.  32 grains.
+ Hydrochloric acid.    8 drops.
+
+This solution will keep for ever, and will be sufficient to last two or
+three years, and with this at hand you will be able in two days to
+prepare a batch of plates at any time. In doing so, you should proceed
+thus: Make up your mind how many plates you mean to make, and take of the
+above accordingly. For two dozen ½-plates or four dozen 3¼ by 3¼,
+dissolve by heat over, but not too near, a spirit lamp, and by yellow
+light, 40 grains of nitrate of silver in 1 ounce of alcohol 0.820. While
+this is dissolving in a little Florence flask on a retort stand at a safe
+distance from the lamp--which it will do in about 5 minutes--take of the
+bromized solution ½ an ounce, of absolute ether 1 ounce, of gun-cotton
+grains; put these in a clean bottle, shake once or twice, and the
+gun-cotton, if good, will entirely dissolve. As soon as the silver is all
+dissolved, and while quite hot, pour out the above bromized collodion
+into a clean 4-ounce measure, having ready in it a clean slip of glass.
+Pour into it the hot solution of silver in a continuous stream, stirring
+rapidly all the while with a glass rod. The result will be a perfectly
+smooth emulsion without lumps or deposit, containing, with sufficient
+exactitude for all practical purposes, 8 grains of bromide, 16 grains of
+nitrate of silver, and 2 drops of hydrochloric acid per ounce. Put this
+in your stock solution bottle, and keep it in a dark place for
+twenty-four hours. When first put in, it will be milky; when taken out,
+it will be creamy; and it will be well to shake it once or twice in the
+twenty-four hours.
+
+At the end of this time you can make your two dozen plates in about an
+hour. Proceed as follows: Have two porcelain dishes large enough to hold
+four or six of your plates; into one put sufficient clean water to nearly
+fill it, into the other put 30 ounces of clear, flat, _not acid,_ bitter
+beer, in which you have dissolved 30 grains of pyrogallic acid. Pour this
+through a filter into the dish, and avoid bubbles. If allowed to stand an
+hour, any beer will be flat enough; if the beer be at all brisk, it will
+be difficult to avoid small bubbles on the plate. At all events, let your
+preservative stand while you filter your emulsion. This must be done
+through perfectly clean cotton-wool into a perfectly clean collodion
+bottle; give the emulsion a good shaking, and when all bubbles have
+subsided, pour it into the funnel, and it will go through in five
+minutes. The filtered emulsion will be found to be a soft, smooth, creamy
+fluid, flowing easily and equally over the plates. Coat with it six
+plates in succession, and place each, as you coat it, into the water. By
+the time the sixth is in, the first will be ready to come out. Take it
+out, see that all greasiness is gone, and place it in the preservative,
+going on till all the plates are so treated.
+
+A very handy way of drying is to have a flat tin box of the usual hot
+plate description, which fill with hot water, then screw on the cap; on
+this flat tin box place the plates to dry, which they will do rapidly;
+when dry, store away in your plate box, and you will have a supply of
+really excellent dry collodion plates.
+
+Just a word as to the preparation of the glasses before coating. It is
+very generally considered that it is better the glasses receive either a
+substratum of albumen or very weak gelatine. I use the latter on account
+of the great ease of its preparation. After your glasses are well
+cleaned, place them in, and rub them with a weak solution of hydrochloric
+acid of the strength of 2 ounces acid to 18 ounces water.
+
+Prepare a solution of gelatine 1 grain to the ounce of water, rinse the
+plate after removal from the acid mixtures, and coat twice with the above
+gelatine substratum; the first coating is to remove the surplus water,
+and should be rejected. Rear the plates up to drain, and dry in a plate
+rack or against a wall, and be careful to prevent any dust adhering to
+the surface while wet.
+
+Having now described the plates I intend to use, let us next consider
+what a transparency is, that we may understand the nature of the work we
+are undertaking. You are all aware that if we take a negative, and in
+contact with it place a sheet of sensitized paper, we obtain a positive
+picture. Substitute for the paper a sensitive glass plate, and we obtain
+also a positive picture, but, unlike the paper print, the collodion or
+other plate will require to be developed to bring the image into view.
+Now this is what is termed making a transparency by contact. It often
+happens, however, that a lantern slide 3¼ by 3¼ has to embrace the whole
+of a picture contained in a much larger negative, so that recourse must
+be had to the camera, and the picture reduced with the aid of a short
+focus lens to within the lantern size; this is what is called making a
+transparency by reduction in the camera. Both cases are the same,
+however, so far as the process being simply one of printing.
+
+Those who have never made a transparency will have doubtless printed
+silver prints from their negatives, and when printing, how often do you
+find that to secure the best results you require to have recourse to some
+little dodge.
+
+Now, let us bear this in mind when using such a negative for the printing
+of a transparency, for, as I have said before, it is only a process of
+printing, after all. Although we cannot, when using a sensitive plate,
+employ the same means of dodging as in the case of a silver print, still
+we are not left without a means of obtaining the same results in a
+different way, and this just brings me to what I have already hinted at
+previously, that a deal more depends on the manipulative skill of the
+operator than in the adoption of any particular make plate or formula;
+and not only does this manipulative skill show itself in the exposure,
+development, etc., but likewise comes into play in a marked manner even
+in the preparation of the negative for transparency printing.
+
+Let me deal with the latter point first. You will at once understand that
+a negative whose size bears a proportion similar to 3¼ by 3¼ will lend
+itself more easily to reduction; thus whole plate or half plate negatives
+are easy of manipulation in this respect, and require but little doing
+up. But as other sizes have at times to be copied into a disk¼ by 3¼,
+recourse must be had to a sort of squaring of the negative. Now, here I
+have a negative 7¼ by 4½, which is perhaps the worst of all sizes to
+compress into the lantern shape, so I have, as it were, to square this
+negative, and this I do by simply adding to sky. I take a piece of
+card-board and gum it on to the glass side of the negative, and this
+addition gives me a size that lends itself easily to reduction to the
+lantern disk, and in no way detracts from the picture.
+
+Having said so much about making up the size, let me add a few words as
+to other preparations that are sometimes necessary. In a good lantern
+transparency, it is, of all things, indispensable that the high lights be
+represented by pure glass, absolutely clean in the sense of its being
+free from any fog or deposit, to even the slightest degree; it is also
+necessary that it be free from everything of heaviness of smudginess in
+the details. To obtain these results, I generally have recourse to the
+strengthening of the high lights of my negatives, and this I do with a
+camel's hair brush and India ink, working on the glass side.
+
+I nearly always block out my skies, and so strengthen the other parts of
+my negatives, that I can rely on a full exposure without fear of
+heaviness or smudginess. This blocking out is easily done.
+
+Haying said so much about the preparation of the negative, let me now
+describe the apparatus I use. I have here an ordinary flat board, and
+here my usual camera; it is the one I use both for outside and inside
+work. It is a whole-plate one, very strongly made, and has a draw of
+twenty-three inches when fully extended; but this is not an unusual
+feature, as nearly all modern cameras have their draw made as long as
+this one. The lens I use is a Ross rapid symmetrical on five inches
+focus, and here I have a broken-down printing frame with the springs
+taken off, and here a sheet of ground glass. This is all that is
+required. I mention this because I find it generally believed that a
+special camera is required for this work, such as to exclude all light
+between the negative and the lens; in my practice I have found this
+unnecessary. There is nothing to hinder the use of ordinary cameras,
+provided the draw is long enough, and the lens a short focus one.
+
+Now let me describe how to go to work. I take the negative and place it
+in the printing-frame, holding it in its place with a couple of tacks,
+film-side next the lens, just as in printing; then stand the printing
+frame on its edge on the flat board, and place the ground glass in front
+of it--when I say in front of it, I mean not between the negative and
+lens, but between the light and the negative. The ground glass can
+conveniently be placed in another printing frame, and both placed up
+against each other. I then bring my camera into play, and so adjust the
+draw and distance from the negative, till I get the picture within the
+disk on my ground glass. I find the best way is to gum a transparency
+mask on the inside of the ground glass; this permits of the picture being
+more easily brought within the required register. This done, focus
+sharply, cap the lens, and then proceed to make the exposure.
+
+Now, what shall I say regarding exposure? Just let us bear in mind again
+that it is merely a printing process we are following up, as you will all
+know that in printing no two negatives are alike in the time they
+require. So in this case no two negatives are the same in their required
+exposure. Still, with the plates I am going to use, so wide is their
+range for exposure that but few failures will be made on this score,
+provided we are on the safe side, and expose fully.
+
+Although these plates are not nearly so fast as gelatine plates, it may
+surprise you to be told that working with a negative which to daylight at
+this dull time of the year required an exposure of sixteen minutes, will,
+I hope, give me good results in about a tenth of this time; and this I
+obtain by burning magnesium ribbon.
+
+At first the error I fell into when using magnesium ribbon was too much
+concentration of light. I now never allow the ribbon, when burning, to
+remain in one position, but keep it moving from side to side, and up and
+down, in front of the ground glass while making my exposure; and if there
+be any dense place in the negative which, as in printing, would have
+required printing specially up, I allow the light to act more strongly on
+that part; the result, as a rule, being an evenly and well exposed plate.
+
+I must not forget to explain to you the manner in which I coil up the
+ribbon before I set it alight. I take an ordinary lead pencil, and wind
+the ribbon round and round, thus making a sort of spiral spring; this
+done, I gently pull the coils asunder. I then grasp the end of the ribbon
+with a pair of pincers, light the other end, and make my exposure.
+
+Having said so much regarding exposure, I shall now proceed to deal with
+development. You will see me use a canary light, with which I can easily
+see to read a newspaper. It may cause some of you surprise to see me use
+so much light. It is the same lamp that I use for developing all my rapid
+bromide plates; it is the best lamp I ever used. The canary medium is
+inserted between the two sheets of glass 7¼ by 4½, the two glasses are
+then fastened on to the tin with gummed paper, a few holes are bored in
+the back for air, a funnel let in, and the thing is complete.
+
+The formula for development is as follows:
+
+Pyro.                96 grains.
+Methylated spirits.   1 ounce.
+Bromide of potash.   12 grams.
+Water.                1 ounce.
+Carbonate ammonia.   60 grains.
+Water.                1 ounce.
+
+Mix 30 drops pyro with from 30 to 60 drops bromide, then add 2 drachms
+ammonia solution and 2 drachms of water.
+
+I find a thin negative requires a slow development, and so gain contrast;
+while hard negatives are best over-exposed and quickly developed.
+
+The plate is first placed in water or rinsed under a gentle stream from
+the tap till all greasiness has disappeared, it is then placed in a flat
+dish, and the developer applied. Should it be found that some parts of
+the picture are denser printed than should be by the ribbon acting more
+strongly on some particular part--this is often the case if the negative
+has been thinner in some parts than others, through uneven coating of the
+plate--the picture need not be discarded as a failure, for I will explain
+to you later on how to overcome this difficulty.
+
+Fix the plate in hypo--the fixing takes place very quickly--then examine
+the picture for the faults above described; if they are found, wash the
+plate under the tap gently, and bring into operation a camel's hair brush
+and a weak solution of cyanide of potassium. Apply the brush to the
+over-printed parts, taking care not to work on the places that are not
+too dense. Do not be afraid to use plenty of washing while this is being
+done; let it be, as it were, a touch of the brush and then a dash of
+water, and you will soon reduce the over-printed parts. It only requires
+a little care in applying the brush.
+
+After this wash well, and should it be deemed necessary to tone to a
+black tone, use a weak solution of bichloride of platinum and chloride of
+gold, or a very weak solution of iridium, in equal quantities, allowing
+the picture to lie in the solution till the color has changed right
+through to the back of the glass. Should a warm pinkish tone be desired,
+I tone with weak solutions of ferri cyanide of potassium, nitrate of
+uranium, and chloride of gold in about equal quantities.
+
+After toning, wash well and dry; they dry quickly. Varnish with Soehnee
+crystal varnish, then mount with covering glasses, and mark. Bind round
+the edges with paper and very stiff gum, and the picture is complete.
+
+The making of a really good transparency is by no means an easy or
+pleasant task with a wet collodion plate, but with these dry plates an
+amateur can, with a little practice, produce comfortably slides quite
+equal to those procurable from professional makers.
+
+       *       *       *       *       *
+
+
+
+
+THE HONIGMANN FIRELESS ENGINE.
+
+
+The invention of a self propelling engine, capable of working without
+fuel economically and for a considerable time, has often been attempted,
+and was, perhaps, never before so nearly accomplished as about the time
+of the introduction into practical use of Faure's electric storage
+batteries; but at the present moment it appears that electric power has
+to give way once more to steam power. Mr. Honigmann's invention of the
+fireless working of steam engines by means of a solution of hydrate of
+soda--NaO HO--in water is not quite two years old, and has in that time
+progressed so steadily towards practical success that it is reasonable to
+expect its application before long in many cases of locomotion where the
+chimney is felt to be a nuisance. The invention is based upon the
+discovery that solutions of caustic soda or potash and other solutions in
+water, which have high boiling points, liberate heat while absorbing
+steam, which heat can be utilized for the production of fresh steam. This
+is eminently the case with solutions of caustic soda, which completely
+absorb steam until the boiling point is nearly reached, which corresponds
+to the degree of dilution. If, therefore, a steam boiler is surrounded by
+a vessel containing a solution of hydrate of soda, having a high boiling
+point, and if the steam, after having done the work of propelling the
+pistons of an engine, is conducted with a reduced pressure and a reduced
+temperature into the solution, the latter, absorbing the steam, is
+diluted with simultaneous development of heat, which produces fresh steam
+in the boiler. This process will be made clearer by referring to the
+following table of the boiling points of soda solutions of different
+degrees of concentration, and by the description of an experiment
+conducted by Professor Riedler with a double cylinder engine and tubular
+boiler as shown in Fig. 2:
+
++---------------------+------------------+----------------------
+|                     | Boiling point in | Steam pressure above
+|  Solution of soda.  |   Centigrades.   | atmospheric pressure
+|                     |                  |   in atmospheres.
++---------------------+------------------+----------------------
+|100 NaO HO +  10 H2O | 256   deg. C.    |     40    atm.
+|      "    +  20  "  | 220.5    "       |     21     "
+|      "    +  30  "  | 200      "       |     15     "
+|      "    +  40  "  | 185.5    "       |     10.2   "
+|      "    +  50  "  | 174.5    "       |      7.7   "
+|      "    +  60  "  | 166      "       |      6.1   "
+|      "    +  70  "  | 159.5    "       |      5.1   "
+|      "    +  80  "  | 154      "       |      4.2   "
+|      "    +  90  "  | 149      "       |      3.6   "
+|      "    + 100  "  | 144      "       |      3.0   "
+|      "    + 120  "  | 136      "       |      2.2   "
+|      "    + 140  "  | 130      "       |      1.6   "
+|      "    + 200  "  | 120      "       |      0.95  "
+|      "    + 300  "  | 110.3    "       |      0.4   "
+|      "    + 400  "  | 107      "       |      0.3   "
++---------------------+------------------+----------------------
+
+_Experiment No. 15_.[3]--The boiler of the engine, Fig. 2, was filled
+with 231 kilogs. water of two atmospheres pressure and a temperature of
+about 135 deg. Cent.; the soda vessel with 544 kilogs. of soda lye of
+22.9 per cent. water and a temperature of 200 deg. Cent., its boiling
+point being about 218 deg. Cent. The engine overcame the frictional
+resistance produced by a brake. At starting the temperature of both
+liquids had become nearly equal, viz., about 153 deg. Cent. The
+temperature of the soda lye could therefore be raised by 47 deg. Cent,
+before boiling took place, but, as dilution, consequent upon absorption
+of steam would take place, a boiling point could only be reached less
+than 218 deg. Cent., but more than 153 deg. Cent. The engine was then set
+in motion at 100 revolutions per minute. The steam passing through the
+engine reached the soda vessel with a temperature of 100 deg. Cent.; the
+temperature of the soda lye began to rise almost immediately, but at the
+same time the steam boiler losing steam above, and not being influenced
+as quickly by the increased heat below, showed a decrease of temperature.
+The difference of the two temperatures, which was at starting 1.3 deg.
+Cent., consequently increased to 7.2 deg. Cent, after 17 min., the boiler
+having then its lowest temperature of 148.8 deg. Cent. After that both
+temperatures rose together, the difference between them increasing
+slightly to 9.5 deg. Cent., and then decreasing continually. After 2 hours
+13 min., when the engine had made 12,000 revolutions, the soda solution
+had reached a temperature of 170.3 deg. Cent., which proved to be its
+boiling point. The steam from the engine was now blown off into the open
+air during the next 24 min. This lowered the temperature of both water
+and soda lye by 10 deg. and re-established its absorbing capacity. The
+steam produced under these circumstances had of course a smaller pressure
+than before, in this way the engine could be driven at reduced steam
+pressures until the resistance became relatively too great. The process
+described above is illustrated by the diagram Fig. 1, which is drawn
+according to the observations during the experiment.
+
+[Footnote 3: Zeitschrift d. Vereins Deutscher Ingenieur, 1883, p. 730;
+1884, p. 69.]
+
+[Illustration: FIG. 1.]
+
+[Illustration: FIG. 2.]
+
+The constant rise of both temperatures during the first two hours, which
+is an undesirable feature of this experiment, was caused by the quantity
+of soda lye being too great in proportion to that of water, and other
+experiments have shown that it is also caused by an increased resistance
+of the engine, and consequent greater consumption of steam. In the latter
+part of the experiment, where the engine worked with expansion, the rise
+of the temperature was much less, and by its judicious application,
+together with a proper proportion between the quantities of the two
+liquids in the engines, which are now in practical use, the rising of the
+temperatures has been avoided. The smaller the difference is between the
+temperatures of the soda lye and the water the more favorable is the
+economical working of the process. It can be attained by an increase of
+the heating surface as well as by a sparing consumption of steam,
+together with an ample quantity of soda lye, especially if the steam is
+made dry by superheating. In the diagrams Figs. 3 and 4, taken from a
+passenger engine which does regular service on the railway between
+Wurselen and Stolberg, the difference of the two temperatures is
+generally less than. 10 deg. Cent. These diagrams contain the
+temperatures during the four journeys _a b c d_, which are performed with
+only one quantity of soda lye during about twelve hours, and show the
+effects of the changing resistances of the engine and of the duration of
+the process upon the steam pressure, which, considering the condition of
+the gradients, are generally not greater than in an ordinary locomotive
+engine. It can especially be seen from these diagrams that an increase of
+the resistance is immediately and automatically followed by an increased
+production of steam. This is an important advantage of the soda engine
+over the coal-burning engine, in consequence of which less skill is
+required for the regular production of steam power. The tramway engines
+of more recent construction according to Honigmann's system--Figs. 5 and
+6--are worked with a closed soda vessel in which a pressure of 1/2 to 1½
+atmospheres is gradually developed during the process. While the counter
+pressure thus produced offers only a slight disadvantage, being at an
+average only 1/2 atmosphere, the absorbing power of the soda lye is
+materially increased, as shown by the following table, and it is,
+therefore, possible to work with higher pressures than with an open soda
+vessel. Besides this great advantage, it is also of importance that the
+pressure in the steam boiler can be kept at a more uniform height.
+
+[Illustration: FIG. 3.]
+
+[Illustration: FIG. 4.]
+
+TABLE.--100_kilogs. Soda Lye containing 20 parts Water with a
+corresponding boiling point of 220 deg. Cent. absorb Steam as follows_:
+
++----------------------------------+--------------+---------------+
+|Final pressure in condenser.      |              |               |
++----------------------------------+Pressure in   |Corresponding  |
+|  0    | ½ atm. | 1 atm. | 1½ atm.|steam boiler. | temperature.  |
++----------------------------------+--------------+---------------+
+|80 kil.|125 kil.|200 kil.|350 kil.|  2 atm.      | 136.0 deg. C. |
+|65  "  | 88  "  |130  "  |190  "  |  3  "        | 143.0   "     |
+|51  "  | 70  "  | 98  "  |125  "  |  4  "        | 153.3   "     |
+|41  "  | 58  "  | 80  "  |100  "  |  5  "        | 160.0   "     |
+|34  "  | 48  "  | 66  "  | 80  "  |  6  "        | 166.5   "     |
+|27  "  | 40  "  | 55  "  | 70  "  |  7  "        | 172.1   "     |
+|22½ "  | 33  "  | 47  "  | 60  "  |  8  "        | 177.4   "     |
+|19  "  | 28  "  | 41  "  | 52  "  |  9  "        | 182.0   "     |
+|16  "  | 24  "  | 35  "  | 46  "  | 10  "        | 186.0   "     |
+|12  "  | 18  "  | 28  "  | 35  "  | 12  "        | 193.7   "     |
+| 9  "  | 14  "  | 22  "  | 33  "  | 15  "        | 200.0   "     |
+| 2  "  |  8  "  | 12  "  | 21  "  | 20  "        | 215.0   "     |
++-------+--------+--------+--------+--------------+---------------+
+
+Not the least important part of the process with regard to its economy is
+the boiling down of the soda lye in order to bring it back to the degree
+of concentration which is required at the beginning of the process. This
+is done in fixed boilers at a station from which the engines start on
+their daily service, and to which they return for the purpose of being
+refilled with concentrated soda lye. It is clear that a closed soda
+vessel has produced as much steam when the process is over as it has
+absorbed, and the quantity of coal required for the evaporation of water
+in concentrating the soda lye can therefore be directly compared with
+that required in an ordinary engine for the production of an equal
+quantity of steam. The boiling down of the soda lye requires, according
+to its degree of concentration, more coal than the evaporation of water
+does under equal circumstances, and disregarding certain advantages which
+the new engine offers in the economy of the use of steam, a greater
+consumption of coal must be expected. But even at the small installation
+for the Aix la Chapelle-Burtscheid tramway with only two boilers of four
+square meters heating surface each, made of cast iron 20 mm. thick, 1
+kilog. of coal converts 6 kilogs. of water contained in the soda lye into
+steam, while in an ordinary locomotive engine of most modern construction
+the effect produced is not greater than 1 in 10. There can be no doubt
+that better results could be obtained if the installation were larger,
+the construction of the boilers more scientific, and their material
+copper instead of cast iron; but even without such improvements the cost
+of boiling down the soda lye might be greatly lessened by the use of
+cheaper fuel than that which is used in locomotive engines, and by the
+saving in stokers' wages, since stokers would not be required to
+accompany the engines.
+
+[Illustration: FIG. 5]
+
+[Illustration: FIG. 6]
+
+Apart from these considerations, the Honigmann engines have the great
+advantage that neither smoke nor steam is ejected from them, and that
+they work noiselessly. The cost of the caustic soda does not form an
+important item in the economy of the process, as no decrease of the
+original quantities had been ascertained after a service of four months
+duration. Besides the passenger engine already referred to, which was
+tested by Herr Heusinger von Waldegg[4] in March, 1884, and which since
+then does regular service on the Stolberg-Wurselen Railway, there are on
+the Aix la Chapelle-Julich railway two engines of 45,000 kilogs. weight
+in regular use, which are intended for the service on the St. Gothard
+Railway. Their construction is illustrated in Figs. 7 and 9, and other
+data are given in a report by the chief engineer of the Aix la
+Chapelle-Julich Railway, Herr Pulzner, which runs as follows:
+
+Wurselen, Dec. 23, 1884.
+
+[Footnote 4: Z.d.V.D.I., 1884, p. 978]
+
+[Illustration: DIAGRAMS FOR THE CALCULATION OF STRESSES IN BOWSTRING
+GIRDERS.]
+
+A trial trip was arranged on the line Haaren-Wurselen, the hardest
+section of the Aix la Chapelle-Julich Railway. This section has a
+gradient of 1 in 65 on a length of 4 kilos; and two curves of 250 and 300
+meters radius and 667 meters length. The goods train consisted of
+twenty-two goods wagons, sixteen of which were empty and six loaded. The
+total weight of the wagons was 191,720 kilogs., and this train was drawn
+by the soda engine with ease and within the regulation time, while the
+steam pressure was almost constant, viz., five atmospheres. The greatest
+load admissible for the coal burning engines of 45,000 kilogs. weight on
+the same section is 180,000 kilogs.
+
+[Illustration: FIG. 7.]
+
+[Illustration: FIG. 8.]
+
+Proof is therefore given that the soda engine has a working capacity
+which is at least equal to that of the coal burning engine. The heating
+surface of the soda engine, moreover, is 85 square meters, while that of
+the corresponding new Henschel engine is 92 square meters. On a former
+occasion I have already stated that the soda engine is capable not only
+of performing powerful work and of producing a large quantity of steam
+during a short time, but also of travelling long distances with the same
+quantity of soda. Thus, for example, a regular passenger train, with
+military transport of ten carriages, was conveyed on Nov. 6, 1884, from
+Aix la Chapelle to Julich and back, i.e., a distance of 45 kilos, by
+means of the fireless engine. The gradients on this line are 1 in 100, 1
+in 80, and 1 in 65, being a total elevation of about 200 meters. For a
+performance like this a powerful engine is required, and a proof of it can
+be recognized in the consumption of steam during the journey, for the
+quantity of water evaporated and absorbed by 4½ to 5 cubic meters soda
+lye was 6,500 liters.
+
+Another certificate concerning the tramway engine illustrated in Figs. 5
+and 6 is of equal interest, and runs as follows:
+
+Aix la Chapelle, Jan. 5, 1885.
+
+A fireless soda engine, together with evaporating apparatus, has been at
+work on the Aix la Chapelle-Burtscheid tramway for the last half year. In
+order to test the working capacity of this locomotive engine, and the
+consumption of fuel on a certain day, the Honigmann locomotive engine was
+put to work this day from 8:45 o'clock a.m. till 8 o'clock p.m., with a
+pause of three-quarters of an hour for the second quantity of soda lye.
+The engine was, therefore, at work for fully 10½ hours, _viz._, 5½ hours,
+with the first quantity, and five with the second. The distance between
+Heinrichsalle and Wilhelmstrasse, where the engine performed the regular
+service, is 1 kilo, and there are gradients
+
+Of about 1 in 30 in 400 meter length.
+   "     1  " 45  " 250    "
+   "     1  " 72  " 350    "
+
+This distance was traversed sixty-four times, the total distance,
+including the journeys to the station, being 66 kilos. The engine gives
+off fully 15-horse power on the steepest gradient, the total traction
+weight being 8½ to 9 tons; it is worked with an average steam pressure of
+5 atmospheres, and has cylinders of 180 mm. diameter and 220 mm. stroke,
+cog wheel-gear of 2 to 3, and driving wheels of 700 mm. diameter. The
+quantity of water evaporated during the service time of 10½ hours was
+found to be about 1,600 kilogs., consequently about 800 kilogs. steam was
+absorbed by one quantity of soda, the weight of which was ascertained at
+about 1,100 kilogs. The averaging heating surface is 9.8 square meters;
+the difference of temperature between soda lye and water was toward the
+end only 3 deg. Cent.; 234 kilogs. pitcoal were used for boiling down the
+lye for the 10½ hours' service, which corresponds to a 6.6 fold
+evaporation.
+
+(Signed) M.F. GUTERMUTH,
+
+Assistant for Engineering at the Technical High School.
+
+HASELMANN,
+
+Manager of the Aix la Chapelle-Burtscheid Tramway.
+
+Here are some unquestionable results. For nearly a year the first railway
+engine, and for six months the first tramway engine of this new
+construction, have been introduced into regular public service, and been
+open to public inspection as well as to the criticism of the scientific
+world. They are worked with greater ease and simplicity than ordinary
+locomotive engines; the economy of their working appears, allowing for
+shortcomings unavoidably attached to small establishments, to be at least
+equally great: they do not emit either steam or smoke, and their action
+is as noiseless as that of stationary engines.
+
+In view of these facts it might be expected that railway managers, who
+are continually told that the smoke of their engines is a serious
+annoyance to the public, would be eager to make themselves acquainted
+with them; it might, in particular, be expected that the managers of the
+underground and suburban railways of this metropolis would lose no time
+in making experiments on their own lines--if only by converting some of
+their old engines into those of the fireless system--and assist a little
+in the development of an invention, in the success of which they have a
+tangible interest which is much greater than that of any railway on the
+Continent, but there is no sign yet of their having done anything.--_E.,
+in The Engineer_.
+
+       *       *       *       *       *
+
+
+
+SIMPLE METHODS OF CALCULATING STRESSES IN GIRDERS.
+
+By CHARLES LEAN, M. Inst. C.E.
+
+
+_Bowstring Girders._--Having had occasion to get out the stresses in
+girders of the bowstring form, the author was not satisfied with the
+common formulæ for the diagonal braces, which, owing to the difficulty of
+apportioning the stresses amongst five members meeting in one point, were
+to a large extent based on an assumption as to the course taken by the
+stresses. As far as he could ascertain it, the ordinary method was to
+assume that one set of diagonals, or those inclined, say, to the
+right-hand, acted at one time, and those inclined in the opposite
+direction at another time, and, in making the calculations, the
+apportionment of the stresses was effected by omitting one set.
+Calculations made in this way give results which would justify the common
+method adopted in the construction of bowstring girders, viz., of bracing
+the verticals and leaving the diagonal unbraced; but an inspection of
+many existing examples of these bridges during the passing of the live
+load showed that there was something defective in them. The long unbraced
+ties vibrated considerably, and evidently got slack during a part of the
+time that the live load was passing over the bridge. In order to get some
+definite formulæ for these girders free from any assumed conditions as to
+the course taken by the stresses, or their apportionment amongst the
+several members meeting at each joint, the author adopted the following
+method, which, he believes, has not hitherto been used by engineers:
+
+Let Fig. 1 represent a bowstring girder, the stresses in which it is
+desired to ascertain under the loads shown on it by the circles, the
+figures in the small circles representing the dead load per bay, and that
+in the large circle the total of live and dead load per bay of the main
+girders. A girder, Fig. 1A, with parallel flanges, verticals, and
+diagonals, and depth equal to the length of one bay, was drawn with the
+same loading as the bowstring. The stresses in the flanges were taken
+out, as shown in the figure, keeping separate those caused by diagonals
+inclined to the left from those caused by diagonals inclined to the
+right. The vertical component of the stress in the end bay of the top
+flange of the bowstring girder, Fig. 1, was, of course, equal to the
+pressure on the abutment, and the stress in the first bay of the bottom
+flange and the horizontal component of the stress in the first bay of the
+top flange was obtained by multiplying this pressure by the length of the
+bay and dividing by the length of the first vertical. The horizontal
+component of the stress in any other bay of the top or bottom flange of
+the bowstring girder--Fig. 1--was found by adding together the product of
+the stress in the parallel flanged girder, caused by diagonals inclining
+to the right, divided by the depth of the bowstring girder at the left of
+the bay, and multiplied by the depth of the parallel flanged girder; and
+the product of the stress caused by diagonals inclining to the left
+divided by the depth of the bowstring girder at the right of the bay,
+multiplied by the depth of the parallel flanged girder. Thus the
+horizontal component of the stress in D=
+ _                                                                _
+| Stress caused by diagonals   Length of right   Depth of parallel |
+|      leaning to left.           vertical.       flanged girder.  |
+|                                                                  | +
+|_           15.75            ×       1/4.5     ×        10       _|
+ _                                                                _
+| Stress caused by diagonals   Length of ver-    Depth of parallel |
+|     leaning to right.        tical to left.     flanged girder.  |
+|                                                                  |
+|_           24               ×       1/8       ×        10       _|
+
+= 65; and the vertical component =
+
+   Horizontal component.     Length of bay.
+
+          65               ×       1/10   × (8.0 - 4.5) = 22.75.
+
+In the same way the horizontal and vertical components of the stresses in
+each of the other bays of the flanges of the bowstring were found; and
+the stresses in the verticals and diagonals were found by addition,
+subtraction, and reduction. These calculations are shown on the table,
+Fig 1B. The result of this is a complete set of stresses in all the
+members of the bowstring girder--see Fig. 2--which produce a state of
+equilibrium at each point. The fact that this state of equilibrium is
+produced proves conclusively that the rule above described and thus
+applied, although possibly it may be considered empirical, results in the
+correct solution of the question, and that the stresses shown are
+actually those which the girder would have to sustain under the given
+position of the live load. Figs. 2 to 10 inclusive show stresses arrived
+at in this manner for every position of the live load. An inspection of
+these diagrams shows: a. That there is no single instance of compression
+in a vertical member of the bowstring girder, b. That every one of the
+diagonals is subjected to compression at some point or other in the
+passage of the live load over the bridge, c. That the maximum horizontal
+component of the stresses in each of the diagonals is a constant
+quantity, not only for tension and compression, but for all the
+diagonals. The diagrams also show the following facts, which are,
+however, recognized in the common formulæ: d. The maximum stress in any
+vertical is equal to the sum of the amounts of the live and dead loads
+per bay of the girder. e. The maximum horizontal component of the
+stresses in any bay of the top flange is the same for each bay, and is
+equal to the maximum stress in the bottom flange. Having taken out the
+stresses in several forms of bowstring girders, differing from each other
+in the proportion of depth to span, the number of bays in the girder, and
+the amounts and ratios of the live and dead loads, similar results were
+invariably found, and a consideration of the various sets of calculations
+resulted in the following empirical rule for the stresses in the
+diagonals: "The horizontal component of the greatest stress in any
+diagonal, which will be both compressive and tensile, and is the same for
+every diagonal brace in the girder, is equal to the amount of the live
+load per bay multiplied by the span of the girder, and divided by sixteen
+times the depth of girder at center." The following formulæ will give all
+the stresses in the bowstring girder, without the necessity of any
+diagrams, or basing any calculations on the assumed action of any of the
+members of the girders:
+
+Let S = span of girder.
+    D = depth at center.
+    B = length of one bay.
+    N = number of bays.
+    L = length of any bay of top flange.
+    l = length of any diagonal.
+    w = dead load per bay of girder.
+    w¹= live load per bay of girder.
+    W = total load per bay of girder = w + w¹.
+
+Then: S/B = N.
+
+Bottom Flange. WNS/8D = maximum stress throughout.    (1)
+
+Top Flange.--In any bay the maximum stress =
+
++ WNS/8D × L/B = + WLN²/8D                            (2)
+
+_Verticals._--The maximum stress = -W.                (3)
+
+_Diagonals._--The maximum stress is
+
+± w¹lS/16DB = ± w¹lN/16D                              (4)
+
+These results show that the method generally adopted in the construction
+of bowstring girders is erroneous; and one consequence of the method is
+the observed looseness and rattling of the long embraced ties referred to
+at the commencement of the article during the passage of the live load;
+the fact being that they have at such times to sustain a compressive
+stress, which slightly buckles them, and sets them vibrating when they
+recover their original position.
+
+Another necessity of the common method of construction is the use of an
+unnecessary quantity of metal in the diagonals; for, by leaving them
+unbraced, the set of diagonals which does act is subjected to exactly
+twice the stress which would be caused in it if the bridge was properly
+constructed. A comparison of the results of a set of calculations on the
+common plan with those given in this paper, shows at once that this is
+the case; for the ordinary system of calculation the stresses, in
+addition to showing compression in the verticals, gives exactly twice the
+amount of tension in the diagonals which they should have.
+
+FIG. 1B.
+________________________________________________________________________________
+                                            |
+          Top Flange Stresses.              |      Stresses in Diagonals.
+                               Hor.    Ver. |
+                                            |
+C= 31.5  × 10/4.5  =         +70.00 = 31.50 |a = 70   -65         =+5.00 = 2.25
+                                            |
+   15.75 × 10/4.5  = 35                     |b =  "     "         =-5.00 = 4.00
+                          \                 |
+D                          > +65.00 = 22.75 |c = 65   -58.33-5    =+1.67 = 1.33
+                          /                 |
+   24    × 10/8    = 30                     |d =  "      "   "    =-1.67 = 1.75
+                          \                 |
+E                          > +58.33 = 14.58 |e = 58.33-55.83-1.67 =+ .83 =  .88
+                          /                 |
+   29.75 × 10/10.5 = 28.33                  |f =   "     "     "  =- .83 = 1.01
+                          \                 |
+F                          > +55.83 =  8.37 |g = 55.83-54.50- .83 =+ .50 =  .59
+                          /                 |
+   33    × 10/12   = 27.5                   |h =   "     "     "  =- .50 =  .61
+                          \                 |
+G                          > +54.50 =  2.72 |i = 54.50-53.67- .50 =+ .33 =  .43
+                          /                 |
+   33.75 × 10/12.5 = 27                     |j =   "     "     "  =- .33 =  .41
+                          \                 |
+H                          > +53.67 =  2.68 |k = 53.67-53.09- .33 =+ .24 =  .28
+                          /                 |
+   32    × 10/12   = 26.67                  |l =   "     "     "  =- .24 =  .24
+                          \                 |
+I                          > +53.09 =  7.97 |m = 53.09-52.67- .24 =+ .18 =  .20
+                          /                 |
+   27.75 × 10/10.5 = 26.42                  |n =   "     "     "  =+ .18 =  .16
+                          \                 |
+J                          > +52.67 = 13.17 |o = 52.67-52.36- .18 =+ .13 =  .11
+                          /                 |
+   21    × 10/8    = 26.25                  |p =   "     "     "  =- .13 =  .06
+                          \                 |
+K                          > +52.36 = 18.33 |
+                          /                 |
+   11.75 × 10/4.5  = 26.11                  |
+                                            |
+L= 23.5  × 10/4.5  =         +52.22 = 23.50 |
+____________________________________________|___________________________________
+                                            |
+      _Bottom Flange Stresses._        |    _Stresses in Verticals._
+                                            |
+                          Hor.              |                              Ver.
+           M same as C = 70.00              |    r = 15 - 4           = - 11.00
+           N    "    D = 65.00              |    s =  5 + 2.25 - 1.75 = -  5.50
+           O    "    E = 58.33              |    t =  5 + 1.33 - 1.01 = -  5.32
+           P    "    F = 55.83              |    u =  5 +  .88 -  .61 = -  5.27
+           Q    "    G = 54.50              |    v =  5 +  .59 -  .41 = -  5.18
+           R    "    H = 53.67              |    w =  5 +  .43 -  .24 = -  5.19
+           S    "    I = 53.09              |    x =  5 +  .28 -  .16 = -  5.12
+           T    "    J = 52.67              |    y =  5 +  .20 -  .06 = -  5.14
+           U    "    K = 52.36              |    z =  5 +  .11        = -  5.11
+           V    "    L = 52.22              |
+____________________________________________|___________________________________
+
+--_The Engineer._
+
+       *       *       *       *       *
+
+
+
+
+A SPRING MOTOR.
+
+
+An exhibition of a spring car motor was given at a recent date at the
+works of the United States Spring Motor Construction Company, Twelfth
+Street and Montgomery Avenue. As a practical illustration of the
+operation of the motor a large platform car, containing a number of
+invited guests and representatives of the press, was propelled on a track
+the length of the shop. (This was in 1883.) The engine, if such it may be
+called, was of the size which is intended to be used on elevated
+railways. As constructed, the motor combines with a stationary shaft a
+series of drums, carrying springs, and arranged so that they can be
+brought into use singly or in pairs. Each spring or section has
+sufficient capacity to run the car, and thus as one spring is used
+another is applied. There is a series of clutches by which the drums to
+which the springs are attached are connected, with a master wheel, which
+transmits through a train of wheels the power of the springs to the
+axles, of the truck wheels. The motor will be so constructed that it may
+be placed on a truck of the width of the cars at present in use, and will
+be nine feet long, with four traction wheels. It is proposed do away with
+the two front wheels and platform, so that the front of the car may rest
+on a spring to the truck. There will be an engine at each end of the
+road, which, it is calculated, will wind up the springs in at least two
+minutes' time.
+
+While the mere construction of such a working motor involved nothing new,
+the real problem involved consisted of the rolling of a piece of steel
+300 feet long, 6 inches wide, and a quarter of an inch thick. Another
+element was the coiling of this strip of steel preliminary to tempering.
+To temper it straight was to expose the grain to unnecessary strain when
+wound in a close coil. To overcome this was the most difficult part of
+the work. At the exhibition the inventor gave an illustration of the
+method which has been employed by the company. The strip of steel is
+slowly passed through a retort heated by the admixture of gas and air at
+the point of ignition in proportions to produce intense heat. When the
+strip has been brought to almost a white heat, it is passed between two
+rollers of the coiling machine. It is then subjected to a powerful blast
+of compressed air and sprays of water, so that six inches from the
+machine the steel is cold enough for the hand to be placed on it. After
+this operation the spring is complete and ready to be placed on the
+shaft. The use of the springs is said to be beyond estimate. They may be
+employed to operate passenger elevators, the springs being wound by a
+hand crank. It is understood that the French Government has applied for
+them for running small yachts for harbor service. Among the advantages
+claimed for this motor are its cheapness in first cost and in operating
+expenses. It is estimated that an engine of twenty-five horse power will
+be required at the station to wind the springs. If there be one at each
+end of the line, the cost for fuel, engineer, and interest will not
+exceed $100 per week. This will answer for fifty or any additional number
+of cars. The company claims that by using twelve springs, each 150 feet
+in length, an ordinary street car can be driven about twenty
+miles.--_Phil. Inquirer_.
+
+       *       *       *       *       *
+
+
+
+
+CASTING CHILLED CAR WHEELS.
+
+
+We show herewith the method employed by the Baltimore Car Wheel Company
+in casting chilled wheels to prevent tread defects. The ordinary mode of
+pouring from the ladle into the hub part of the mould, and then letting
+the metal overpour down the brackets to the chill, produces cold shot,
+seams, etc. In the arrangement here shown the hub core, A, has a concave
+top, B, and the core seat, C, is convex, its center part being lower than
+the perimeter of the top of the core. Figs. 3, 4, show the core, A, in
+the side elevation and in plain. Fig. 2 is a core point forming a space
+to connect the receiving chamber, E, above, with the mould by
+passageways, D D, formed in the side of the top of the core. The combined
+area of these passageways being less than that of the conduit, F, from
+the receiving chamber, the metal is skimmed of impurities, and the latter
+are retained in the receiving chamber, E. The entering metal flows first
+to the lower hub part at H H, thence by the sprue-ways, G G, to the lower
+rim part at J J, being again skimmed at the mouth of the sprue-ways. Thus
+the rim fills as rapidly as the hub, and the metal is of a uniform and
+high temperature when it reaches the chill.
+
+[Illustration: CASTING OF CAR WHEELS.]
+
+In the wheels made by this firm, every alternate rib is connected with
+the rim, and runs off to nothing near the hub; the intermediate ribs are
+attached to the hub, and diminish in width toward the rim.--_Jour.
+Railway App._
+
+       *       *       *       *       *
+
+
+
+
+ELECTRICITY AND PRESTIDIGITATION.
+
+
+The wonderful ease with which electricity adapts itself to the production
+of mechanical, calorific, and luminious effects at a distance, long ago
+gave rise to the idea of applying it to certain curious and amusing
+effects that simple minds willingly style _supernatural_, because of
+their powerlessness to find a satisfactory explanation of them.
+
+[Illustration: FIG. 1.--RAPPING AND TALKING TABLE. ]
+
+Who has not seen, of old, Robert Houdin's heavy chest and Robert Houdin's
+magic drum? These two curious experiments are, as well known, founded
+upon the properties of electro-magnets.
+
+At present we shall make known two other arrangements, which are based
+upon the same action, and which, presenting old experiments under a new
+form, rejuvenate them by giving them another interest.
+
+The first apparatus (Fig. 1), which presents the appearance of an
+ordinary round center table, permits of reproducing at will the "spirit
+rappings" and sepulchral voice experiments. The table support contains a
+Leclanche pile, of compact form, carefully hidden in the part that
+connects the three legs. The top of the table is in two parts, the lower
+of which is hollow, and the upper forms a cover three or four millimeters
+in thickness. In the center of the hollow part is placed a vertical
+electro-magnet, one of the wires of which communicates with one of the
+poles of the pile, and the other with a flat metallic circle glued to the
+cover of the table. Beneath this circle, and at a slight distance from
+it, there is a toothed circle, F, connected with the other pole of the
+pile. When the table is pressed lightly upon, the cover bends and the
+flat circle touches the toothed one, closes the circuit of the pile upon
+the electro-magnet, which latter attracts its armature and produces a
+sharp blow. On raising the hand, the cover takes its initial position,
+breaks the circuit anew, and produces another sharp blow. Upon running
+the hand lightly over the table, the cover is caused to bend successively
+over a certain portion of its circumference, contacts and breakages of
+the circuit are produced upon a certain number of the teeth, and the
+sharp blow is replaced by a quick succession of sounds, or a tremulous
+one, according to the skill of the medium whose business it is to
+interrogate the spirits. As the table contains within it all the
+mechanism that actuates it, it may be moved about without allowing the
+artifice to be suspected.
+
+[Illustration: FIG. 2.--ELECTRIC INSECTS.]
+
+The table may also be operated at a distance by employing conductors
+passing through the legs and under the carpet and communicating with a
+pile whose circuit is closed at an opportune moment by a confederate
+located in a neighboring apartment.
+
+Finally, on substituting a small telephone receiver for the
+electro-magnet, and a microtelephone system for the ordinary pile, we
+shall convert the rapping spirits into talking ones. With a little
+exercise it will be easy for the confederate to transmit the conversation
+of the "spirits" in employing sepulchral tones to complete the illusion.
+
+Fig. 2 represents a device especially designed as a parlor ornament. When
+the plant is touched, the insects resting upon it immediately begin to
+flap their wings as if they desired to fly away. These insects are
+actuated by a Leclanche pile hidden in the pot that contains the plant.
+The insect itself is nothing else than a mechanism analogous to that of
+an ordinary vibrating bell. The body forms the core of a straight
+electro-magnet, _c_, which is bent at right angles at its upper part, and
+in front of which is placed a small iron disk, _b_, forming the animal's
+head. This head is fixed upon a spring, like the armature of ordinary
+bells, and causes the wings to move to and fro when it is successively
+attracted and freed by the electro-magnet. The current is interrupted by
+means of a small vibrating device whose mode of operation may be easily
+understood by glancing at the section in Fig. 2. The current enters the
+electro-magnet through a fine copper wire hidden in the leaves and
+connected with the positive pole of the pile. The negative pole is
+connected with the bottom of the pot. The wire from the vibrator of each
+insect reaches the bottom of the flower-pot, but does not touch it. A
+drop of mercury occupies the bottom of the pot, where it is free to move
+about. It results that if the pot be taken into the hand, the exceedingly
+mobile mercury will roll over the bottom and close the circuit
+successively on the different insects, and keep them in motion until the
+pot has been put down and the drop of mercury has become immovable.
+
+       *       *       *       *       *
+
+
+
+
+PORTABLE ELECTRIC SAFETY LAMPS.
+
+
+One of the most difficult problems that daily presents itself in large
+cities is how to proceed without danger in the search for leakages in gas
+mains, or in attempts to save life in houses accidentally filled with
+explosive gases. The introduction of a flame into such places leads in
+the majority of cases to accidents whose consequences cannot be
+estimated. The reader will remember especially the explosion which
+occurred some time ago in St. Denis Street, Paris, and which killed a
+considerable number of persons. It has, therefore, been but natural to
+think of the use of electricity, which gives a bright line without a
+flame, in order to allow life-saving corps and firemen to enter buildings
+filled with an explosive mixture, without any risk whatever.
+
+[Illustration: FIG. 1.--ELEVATION (Scale 1/25).]
+
+Several electricians have proposed ingenious portable apparatus for this
+purpose, and, among these, Mr. A. Gerard, whose device we illustrate
+herewith. In this system the electric generator is stationary, and
+remains outside the building. This, along with all the rest of the
+apparatus, is mounted upon a carriage. The operator, instead of carrying
+a pile to feed the lamp, drags after him a very elastic cable containing
+the two conductors. This "Ariadne's thread" easily follows all
+sinuosities, and adapts itself to all circumvolutions. The entire
+apparatus, being mounted upon a carriage, can be easily drawn to the
+place of accident like a fire engine.
+
+[Illustration: FIG. 2.--PLAN (Scale 1/25).]
+
+_General Description_.--Fig. 1 shows the carriage. In the center, over
+the axle, is mounted a dynamo-electric, machine, D, driven by a series of
+gear wheels that are revolved by winches, MM. Upon the shaft, A, is fixed
+a hand wheel, V, designed to regulate the motion. In the forepart of the
+carriage are placed two windlasses, TT, permanently connected with the
+terminals of the dynamo. Upon each of these is wound a cable formed of
+two conductors, insulated with caoutchouc and confined in the same
+sheath. Each windlass is provided with five hundred feet of this cable,
+the extremity of which is attached to two lanterns each containing an
+incandescent lamp. These lanterns, are inclosed in boxes, BB, with double
+sides, and cross braced with springs so as to diminish shocks. Under the
+windlass there is a case which is divided into two compartments, one of
+which contains tools and fittings, and the other, six carefully packed
+incandescent lamps, to be used in case of accident to the lanterns. At
+the rear end of the carriage there is a hinged bar, C, designed to
+support it at this point and give it greater stability during the
+maneuvers. The stability is further increased by chocking the wheels.
+
+[Illustration: FIG. 3.--HAND LANTERN (Scale 1/4).]
+
+_Maneuver of the Apparatus_.--The carriage, having reached the place of
+accident, is put in place, its rear end is supported by the bar, C, the
+wheels are chocked, and the winches are placed upon the dynamo gearing.
+Two strong men selected for the purpose now seize the winches and begin
+to revolve them, and the lamps immediately light while in their boxes.
+Another man, having opened the latter, takes out one of the lanterns and
+enters the dangerous place, dragging after him the elastic cable that
+unwinds from the windlass. Two men are sufficient to turn the winches for
+five minutes; with a force of six men to relieve one another the
+apparatus may therefore be run continuously.
+
+[Illustration: FIG. 4.--POLE LANTERN (Scale 1/4).]
+
+The dynamo, which is of strong and simple construction, is inclosed in a
+cast iron drum, and is consequently protected against accident. With a
+power of 25 kilogrammeters it furnishes a current of 40 volts and 7
+amperes, which is more than sufficient to run two 50-candle incandescent
+lamps. The winches are removable, and are not put upon the shaft until
+the moment they are to be used.
+
+The windlasses, as above stated, are permanently connected with the
+terminals of the dynamos. The current is led to them through their
+bearings and journals. Their shaft is in two pieces, insulated from one
+another. One extremity of the cable is attached to these two pieces, and
+the other to the lantern. Each windlass is provided with a small winch
+that allows the cable to be wound up quickly.
+
+[Illustration: FIG. 5.--WINDLASS (Scale 1/10).]
+
+The two lanterns are different, on account of the unlike uses to which
+they are to be put. One of them is a hand-lamp that permits of making a
+quick preliminary exploration. The second is to be fixed by a socket
+beneath it to a pole that is placed along the shafts of the carriage.
+This lantern, upon being thrust into a chimney, shaft, or well, permits
+of a careful examination being made thereof. As the handle terminates in
+a point; it may be stuck into the ground, to give a light at a sufficient
+height to illuminate the surroundings.
+
+The hand lantern consists of a base, P, provided with three feet. At the
+top there is a threaded circle to which is attached a movable handle, K,
+that is screwed on to a ring, C. These three pieces, which are of bronze,
+are connected by 12 steel braces, E, that form a protection for the
+glass, M. The lantern is closed above by a thick glass disk, G. The
+luminous rays are therefore capable of spreading in all directions. Tight
+joints are formed at every point by rubber or leather washers.
+
+[Illustration: FIG. 6.--LANTERN BOX (Scale 1/10).]
+
+In the center of the lantern is placed the incandescent lamp. This is
+held in a socket, and is provided with two armatures to which the
+platinum wires are soldered. Two terminals, b, are affixed to the lamp
+socket. Beneath the lantern there is a cylindrical box provided with a
+screw cap. In one side of this box there is a tubulure that gives passage
+to the electric cable whose conductors are fastened to the terminals. A
+conical rubber sleeve, R, incloses the cable, which is pressed by the
+screw cap, S. A special spring, Y, attached at one end to the top of the
+lantern, and at the other to the cable, X, is designed to deaden the too
+sudden shocks that the lantern might be submitted to, and that would tend
+to pull out the cable.
+
+As a result of the peculiar arrangement of this lantern, the lamp is
+constantly surrounded with a certain quantity of air that would certainly
+suffice to consume the carbons in case of a breakage of the globe without
+allowing any lighted particles to escape to the exterior. Besides, should
+the terminals become unscrewed, and should the conductors thus rendered
+free produce sparks, the latter would be prevented from reaching the
+exterior by reason of the absolute tightness of the box. In case the
+incandescent lamp should get broken, the only inconvenience that would
+attend the accident would be that the man who held the lantern would be
+for a moment in the dark. When he reached the carriage, it would be only
+necessary for him to take off the glass disk, take the broken lamp out of
+its socket, insert a new one, and then put the glass top on again.--_Le
+Génie Civil_.
+
+       *       *       *       *       *
+
+Voltaic batteries containing solutions of ammonium chloride and zinc
+chloride can, according to the recent researches of M. Onimus, be
+converted into dry piles by mixing these solutions with plaster of Paris,
+and allowing the mixture to solidify. If mixtures of ferric oxide and
+manganese peroxide with plaster of Paris are employed, the electromotive
+force is slightly higher than with plaster of Paris alone; and when
+ferric oxide is used, the battery quickly regains its original strength
+on breaking the circuit. When the battery is exhausted, the solid plaster
+of Paris has simply to be moistened again with the solution.
+
+       *       *       *       *       *
+
+
+
+
+THE ELECTRIC DISCHARGE AND SPARK PHOTOGRAPHED DIRECTLY WITHOUT AN
+OBJECTIVE.
+
+
+The study of the form and color that electric discharges exhibit,
+according to the different ways in which they are produced, has already
+enticed a certain number of amateurs and scientists. Every one knows the
+remarkable researches of the lamented Th. Du Moncel on the induction
+spark, and during the course of which he, in 1853, discovered that
+phenomenon of the electric efflux which has since been the object of
+important researches on the part of several physicists and chemists,
+among whom must be cited Messrs. Thenard, Hautefeuille, and Chapuis.
+Twenty years ago, Mr. Bertin, who was then Professor at the Faculty of
+Strassburg, and who was afterward subdirector of the normal school, was
+directing his researches upon the electric discharges produced by high
+tension apparatus, plate machines, and Leyden jars. He thought, with
+reason, that, on account of its rapidity and complexity, a portion of the
+phenomenon must escape the eye of the observer, and so the idea occurred
+to him to photograph the discharge in order to afterward study its forms
+more at his leisure. We have recently had an opportunity of seeing a
+negative which was obtained by him at that epoch; but the photographic
+processes then in use probably did not allow him to obtain others that
+were as satisfactory, and he had given up this kind of study, when, last
+year, he had an opportunity of speaking of it to the well known
+manufacturer Mr. F. Ducretet, whom he induced to take it up and employ
+the new gelatino-bromide process. Unfortunately, he died before these
+experiments were begun, and was unable to see the realization of his
+project. Mr. Ducretet did not abandon the idea, but constructed the
+necessary apparatus, and obtained the results that we now place before
+our readers.
+
+[Illustration: FIG 1.]
+
+His apparatus, which contains no photographic objective, consists of an
+oblong case, ABCD, made of red glass and resting upon an ebonite table
+supported by one leg (Fig. 1). In the top of the case, as well as in the
+two sides, AD and BC, are apertures that are closed by ebonite cylinders
+through which slide, with slight friction, copper rods, HLN. In the leg
+of the table there is a copper rack which may be maneuvered from the
+interior by a pinion, and which communicates electrically with a
+terminal, E. The upper part of this rack, which enters the glass case, is
+threaded, so that there may be affixed to it either a metallic or an
+insulating disk. The rods, HLN, are likewise threaded, so that there may
+be affixed to their internal extremities balls, points, combs, and disks
+of metal or of insulating material at will.
+
+[Illustration: FIG 2.]
+
+In short, we have here a transparent box (impermeable to photogenic rays)
+into which electricity may be led by means of four conductors that are
+arranged two by two in a line with each other, or in perpendicular
+positions, and that may be made to approach or recede from one another by
+maneuvering them from the exterior. This very simple arrangement answers
+every requirement, and, upon placing a sensitized plate in the vicinity
+of the conductors, permits of photographing the electric discharge
+directly and, so to speak, before the eyes of the operator.
+
+As a source of electricity, use is made of a bichromate of potash
+battery of 6 elements, capable of giving 10 volts and 15 amperes. The
+current from this battery is converted into a current of high tension by
+means of a strong induction coil capable of giving sparks more than eight
+inches in length. The discharge shown in Fig. 4 was obtained by means of
+a Holtz machine. Each experiment lasted less than a second.
+
+[Illustration: FIG. 3.]
+
+Figs. 2 and 3 represent the efflux that occurred under; the following
+conditions: The disk, P, was of metal, and was connected with the
+negative pole of the induction coil; and upon it was laid the
+photographic plate with the sensitized film downward, and consequently
+touching the disk. This is what produced the opaque circle in the center.
+Then the photographic plate was entirely covered with a thin ebonite
+plate, above which there was a second one supported by small wedges, so
+as to allow air to circulate between them. Finally, upon this second
+ebonite plate there was placed another photographic plate, with its
+sensitized film upward and directly in contact with an upper metallic
+disk, and connected with the positive pole of the coil by the conductor,
+L. An inspection of Figs. 2 and 3 shows that the, efflux does not possess
+the same form at the two poles. We remark at the positive pole a quite
+wide opaque circle surrounded by a sort of aureola composed of an
+infinite number of very delicate rays, while at the negative pole the
+aureola seems not to have been able to spread. We see, moreover, the same
+phenomenon in examining Fig. 4 (which represents the efflux obtained by
+means of a Holtz machine), but this time in a horizontal direction. The
+photographic plate was here placed upon the non-conducting disk, P. As
+the sensitized film was upward, it was put in contact with the balls at
+the extremity of the conductors, H and N.
+
+[Illustration: FIG. 4.]
+
+It will be seen here again that the efflux spreads out widely at the
+positive pole, while it is contracted at the other. The conducting balls
+were spaced 0.04 inch apart. A spark leaped from one to the other at the
+moment the current was being interrupted.
+
+In Fig. 5 we are enabled to study with more ease a spark obtained with
+nearly the same arrangement. The balls, H and N, did not here rest
+directly upon the sensitized film, but upon two small sheets of tin
+cemented to the extremities of the plate at 0.06 inch apart. In addition,
+the source employed was not the Holtz machine, but the pile with
+induction coil. Two nearly parallel sparks were obtained. It will be seen
+that these are very complex. Each of them seems to be formed of four
+lines of different sizes, entangled with one another and presenting
+different sinuosities. Aside from this, the plate is traversed for a
+space of 0.04 of an inch by curved lines running from one pole to the
+other, and exhibiting numerous sinuosities.
+
+[Illustration: FIG. 5.]
+
+Fig. 6 represents a discharge that occurred under the following
+circumstances: The disk, P, being metallic and connected with one of the
+poles, there was placed upon it a thin ebonite plate of the same
+dimensions as the photographic one, and then the latter with the
+sensitized pellicle upward. Finally, the pellicle was put in contact with
+the upper conductor, L, which terminated in a ball and was connected with
+the other pole of the induction coil.
+
+It will be seen that, despite the two dielectrics (ebonite and glass)
+interposed, and the opacity of one of them, the efflux that occurred
+around the disk, P, is quite sharply reproduced upon the sensitized plate
+by a circle like that which we observed in Figs. 2 and 3. It will be
+seen, besides, that an infinite number of ramifications in every
+direction has been produced around the ball, and we can follow the travel
+of the spark that leaped between the ball and disk in two directions
+situated in the prolongation of one another.
+
+Under the two principal and clearly marked lines that this spark made
+there are seen two other, very pale and much wider ones, that present no
+sinuosities parallel with the first.
+
+The results of these experiments are very curious. The position of the
+plates was varied in 18 different ways, as was also the form of the
+conductors. We have spoken of those only that appear to us to present the
+most interest. Unfortunately, notwithstanding the skill of the engraver,
+it is impossible to render with accuracy all the details that are seen
+upon examining the negative. The proofs that have been printed upon paper
+present much less sharpness than the negative, for there are certain
+parts of the figures on the glass that do not show in the print.
+
+[Illustration: FIG. 6.]
+
+We have been content here to make known the results obtained, without
+drawing any conclusions from them. It is to be hoped that these
+experiments, which can be easily repeated by means of the apparatus
+described above, will be repeated and discussed by electricians, and that
+they will contribute toward making known to us the nature of the
+mysterious agent that will give its name to our era.--_G. Mareschal,
+in La Lumiere Electrique._
+
+       *       *       *       *       *
+
+
+
+
+THE TRUE CONSTANT OF GRAVITY.
+
+
+Many of the readers of this journal may like to participate in the
+discussion of the following proposition. The statement is this:
+
+The space through which a body, near the surface of the earth, at mean
+latitude, _in vacuo_, descends by virtue of the accelerating force of
+gravity in 1/1000 of an hour is precisely 2,500 geometric inches = 100
+geometric cubits = the side of a square geometric acre.
+
+[The geometric inch is taken, in accordance with the view of Sir John
+Herschel, at 1/1,000,000,000 of twice the polar axis of the earth, and
+equals 1-1/1000 English inches very nearly.]
+
+The strict decimal relation of the proposition is shown by the following
+table. It has been tested by Clairaut's theorem, and by other existing
+expressions, and has been found to agree, far within the probable limits
+of errors in observation, with the most approved values of the constant.
+In fact, it is contained in the existing expressions; but the _decimal_
+relation does not appear unless we state the unit of linear measure as a
+decimal of the earth's semi-polar axis, and, at the same time, divide the
+circle, both for time and for general purposes, _geometrically, i.e._, by
+strict decimalization upon the hour-angle. A mathematical reason
+underlies the proposition.
+
+Time in       Acquired    Squares   Total      Ratio of       Descent in
+Thousandths   Velocity,   of the    Descent,   Spaces, Each   Successive
+of an Hour.   Cubits.     Time.     Cubits.    Interval of    Intervals,
+                                               Time.          Cubits.
+
+     1           200          1         100          1             100
+     2           400          4         400          3             300
+     3           600          9         900          5             500
+     4           800         16       1,600          7             700
+     5         1,000         25       2,500          9             900
+     6         1,200         36       3,600         11           1,100
+     7         1,400         49       4,900         13           1,300
+     8         1,600         64       6,400         15           1,500
+     9         1,800         81       8,100         17           1,700
+    10         2,000        100      10,000         19           1,900
+
+So that--
+                                                    Cubits.   Acre Sides.
+In 1/10,000 of an hour, the total
+descent =                                                1  =       1/100
+
+In 1/1000 of an hour, the total descent =              100  =      1
+
+In 1/100 of an hour, the total descent =            10,000  =    100
+
+And so on, in strict _decimal_ relation with the earth's semi-polar axis.
+
+A two-fold reason why the constant for latitude 45° is vastly better than
+any other, is in its having this simple relation with the semi-axis, and
+at the same time a less complex way of applying the correction for
+latitude.
+
+JACOB M. CLARK.
+
+New York, February, 1885.
+
+       *       *       *       *       *
+
+
+
+
+ORIGIN OF THUNDERSTORMS.
+
+
+At the recent congress of German medical men and physicists, Dr. S.
+Hoppe, of Hamburg, read a paper in which he sought to show that the
+electricity of thunderstorms is generated by the friction of vapor
+particles generated by the evaporation of water. This opinion was
+strengthened by several experiments in which compressed cold air was
+allowed to rush into a copper vessel containing warm moist air, thus
+generating a large amount of electricity. He concludes that the rise of a
+column of warm moist air into the colder atmosphere above will be
+followed by a thunderstorm if it acquires sufficient velocity to prevent
+neutralization of the electricity generated by the friction of the air.
+Hence, in his opinion, open districts denuded of forests are more liable
+to thunderstorms than wooded regions, where the trees forbid the rise of
+humid air currents.
+
+       *       *       *       *       *
+
+
+
+
+IMPROVISED TOYS.
+
+
+Do our readers remember all those ingenious toys which our mothers and
+sisters improvised in order to amuse us? We took a walk into the country,
+and our eldest sister or our mother picked a wild poppy, turned its red
+petals back and encircled them with a thread, and stuck a sprig of grass
+into the seed vessel to represent a headdress of feathers. Here was a
+fresh and pretty doll (Fig. 1). Another day it was the season of lilacs.
+The children gathered branches by the armful, and from these the mother
+picked off the flowers and strung them one by one with a needle. Here was
+a bracelet or a necklace. An acorn was picked up in the woods, the mother
+carved it with a pen-knife, and behold a basket. From a nutshell she made
+a boat, and from a green almond a rabbit. Sometimes she carved the
+rabbit's ears out of the almond itself, but in most cases they were made
+from a pretty rose-colored radish.
+
+[Illustration: FIG. 1.--Doll made of a Wild Poppy.]
+
+Do you remember the cork from which, by the aid of a few long needles for
+bars, an ingenious fly-cage was formed? And the castle of cards, four,
+five, and eight stories high? And then those famous card tents in a row,
+that fell one after another when the first one in the line was
+overturned?
+
+[Illustration: FIG. 2.--Hygrometric Doll; its Dress Colored with
+Chloride of Cobalt.]
+
+How we passed the evenings with our eyes fixed upon our mothers, who
+patiently, with their skillful scissors, cut horses and dogs out of old
+white, red, and blue cards! And how many plays, without costing a cent,
+served to amuse the children by exercising their ingenuity! The mother
+marked at hazard five dots upon a sheet of paper. The question was to
+draw a man, one of the dots showing the place of the head and the other
+four the feet and hands.
+
+[Illustration: FIG. 3.--Old Man made of Lobster's Claws.]
+
+When the dessert was brought upon the table, it became a question of
+manufacturing a head out of an orange. That is not very difficult; two
+holes for the eyes, a large slit for the mouth, and nothing easier than
+to simulate the teeth and nose. The head was placed upon a napkin
+stretched over the top of a champagne glass. This was one of our great
+amusements. The napkin was drawn ultimately to the right and left, and
+this moved the head and caused it to assume most comical positions. But
+what caused irresistible laughter was when a sly hand pressed the head
+and made it open its mouth wide. And then what pigs we manufactured with
+a lemon perched upon four matches!
+
+[Illustration: FIG. 4.--Crocus Flowering in a Perforated Pot.]
+
+Without mentioning Chinese shadows, how many cheap amusements there are
+that can be varied to infinity merely by various combinations of the
+fingers interlocked in diverse manners!
+
+[Illustration: FIG. 5.--1. Paper Cross. 2. Method of Making the
+Cross. 3. Rabbits Made of Green Almonds. 4. Basket Made of Sedges. 5.
+Acorn Basket. 6. Fly-cage Made of a Cork.]
+
+All such amusements were much in vogue in former times, but we are
+assured that to-day mothers are less conversant with these curious and
+droll inventions, which were once transmitted like the tales of Mother
+Goose. They buy playthings for their children at great expense, and allow
+the latter to amuse themselves all by themselves. The toy paid for and
+given, the child is no longer in their mind. Those mothers who have
+preserved the traditions of these little pastimes, and know how to
+skillfully vary them, find therein so many resources for amusing their
+children. Then it is so pleasant to see the eyes of the latter eagerly
+fixed upon the scissors, and to hear their exclamations of pleasure and
+their fresh laughter when the paper is transformed under expert fingers
+into a boat, house, or what not!
+
+[Illustration: FIG. 6.--The Lesson in Drawing.--An Illustrated
+Five-spot of Hearts.]
+
+It has required millions of mothers and nurses to put their wits to work
+to amuse their children in order to form that collection of charming
+combinations that at present constitutes a sort of science. Mr. Gaston
+Tissandier not long ago conceived the happy idea of bringing together in
+an illustrated volume a description of some of these improvised toys and
+amusing plays, and it is from this that the accompanying illustrations
+(which sufficiently explain themselves) are taken.
+
+       *       *       *       *       *
+
+
+
+
+THE ÆOLIAN HARP.
+
+
+The Æolian harp is a musical instrument which is set in action by the
+wind. The instrument, which is not very well known, is yet very curious,
+and at the request of some of our readers we shall herewith give a
+description of it.
+
+[Illustration: FIG. 1.--KIRCHER'S ÆOLIAN HARP.]
+
+According to a generally credited opinion, it is to Father Kircher, who
+devised so many ingenious machines in the seventeenth century, that we
+owe the first systematically constructed model of an Æolian harp. We must
+add, however, that the fact of the spontaneous resonance of certain
+musical instruments when exposed to a current of air had struck the
+observers of nature in times of remotest antiquity.
+
+Without dwelling upon the history of the Æolian harp, we may say that in
+modern times this instrument has been especially constructed in England,
+Scotland, Germany, and Alsace. The Æolian harp of the Castle of Baden
+Baden, and those of the four turrets of Strassburg Cathedral are
+celebrated.
+
+[Illustration: FIG. 2.--FROST & KASTNER'S IMPROVED ÆOLIAN HARP.]
+
+We shall first describe Kircher's harp, which this Jesuit savant
+constructed according to an observation made by Porta in 1558. The
+instrument consists of a rectangular box (Fig. 1), the sounding board of
+which, containing rose-shaped apertures, is provided with a certain
+number of strings stretched over two bridges and fastened to pegs at the
+extremities. This box carries a ring that serves for suspending it.
+Kircher recommends that the box be made of very sonorous fir wood, like
+that employed in the construction of stringed instruments. He would have
+it 1.085 meters in length, 0.434 meter in width, and 0.217 meter in
+height, and would provide it with fifteen catgut strings, tuned, not like
+those of other instruments to the third, fourth, or fifth, but all in
+unison or to the octave, in order, says he, that its sound shall be very
+harmonious. The experiments of Kircher showed him the necessity of
+employing a sort of concentrator in order to increase the force of the
+wind, and to obtain all the advantage possible from the current of air
+that was directed against the strings. The place where the instrument is
+located should not, according to him, be exposed to the open air, but
+must be a closed one. The air, nevertheless, must have free access to it
+on both sides of the harp. The force of the wind may be concentrated upon
+such a point in different ways; either, for example, by means of conical
+channels, or spiral ones like those used for causing sounds to reach the
+interior of a house from a more elevated place, or by means of a sort of
+doors. These latter, two in number, are adapted to a kind of receptacle
+made of boards and presenting the appearance of a small closet. In the
+back part of this receptacle there is a slit, and in front of this the
+harp is hung in a slightly oblique position. The whole posterior portion
+of the apparatus must be situated in the apartment, while the doors must
+remain outside the window (Fig. I). In later times the Æolian harp has
+been improved by Messrs. Frost and Kastner, whose apparatus is
+represented in Fig. 2. It consists of a rectangular box with two sounding
+boards, each provided with eight catgut strings. In order to limit the
+current of air and to bring it with more force against the strings, two
+wings are adapted near the thin surfaces opposed to the wind, so that the
+current may reach each group of cords on passing through the narrow
+aperture between the obliquely inclined wing and the body of the
+instrument. The dimensions of the resonant box are as follows: height,
+1.28 meters; width, 0.27 meter; and thickness, 0.075 meter. Distance
+between the two bridges, or length of the sonorous portion of the cords,
+about 1 meter; width of the wings, 0.14 meter. Distance between the
+sounding board and the wings, 0.42 meter. Inclination of the wings, 50
+degrees.
+
+[Illustration: FIG. 3.--ÆOLIAN HARP IN THE OLD CASTLE OF BADEN
+BADEN.]
+
+The celebrated Æolian harps of the old castle of Baden Baden are entirely
+different, and merit description. One of them (Fig. 3) is formed of a
+resonant box, the construction of which differs from that of Æolian harps
+with a rectangular box, in that it is prolonged beyond the place occupied
+by the strings, and is rounded off behind. In the opposite side there are
+two long and narrow apertures. To prevent the apparatus from being
+injured by the weather, it is inclosed in a sort of case occupying the
+recess of the window in the old ruined castle in which it is exposed.
+Behind the harp there is a wire lattice door, the purpose of which seems
+to be to protect the instrument against the attempts of robbers or the
+indiscreet contact of tourists. We annex to the general view of the
+instrument a front and profile plan (Fig. 4). The Æolian harp has often
+inspired both writers of prose and poetry. Chateaubriand, in _Les
+Natchez_, compares its sounds to the magic concerts that the celestial
+vaults resound. Without attributing such effects to the instrument, it
+must be admitted that it possesses remarkable properties, which act upon
+the nervous system and cause very different impressions, according to the
+temperament of those who listen to its accords.
+
+[Illustration: FIG. 4.--PLAN OF THE BADEN BADEN INSTRUMENT.]
+
+Hector Berlioz, in his _Voyage Musicale en Italie_, has given as follows
+the curious effects that an Æolian harp produced upon his lively and
+impassioned imagination: "On one of those gloomy days that sadden the end
+of the year, listen, while reading Ossian, to the fantastic harmony of an
+Æolian harp swinging at the top of a tree deprived of verdure, and I defy
+you not to experience a profound feeling of sadness and of _abandon_, and
+a vague and infinite desire for another existence."
+
+An English physician, Dr. J.M. Cox, in his practical _Observations_ upon
+dementia, asserts that unfortunate lunatics have been seen whose
+sensitiveness was such that ordinary means of cure had to be given up
+with them, but who were instantly calmed by the sweet and varied accords
+of an Æolian harp. Other observers narrate that they have heard the
+efficacy of Aeolian sounds spoken of in Scotland for producing sleep.
+
+Telegraph wires are often, under the influence of the winds, submitted to
+vibrations which reproduce the phenomena of the Aeolian harp. The
+electric telegraph, which, before the construction of the Kehl bridge,
+directly traversed the Rhine, very frequently resounded, and the observer
+who placed his ear against the poles on the bank of the river was enabled
+to hear something like a far-off sound of bells.--_La Nature_.
+
+       *       *       *       *       *
+
+
+
+
+PHYSICS WITHOUT APPARATUS.
+
+MANUFACTURE OF ILLUMINATING GAS.
+
+
+[Illustration: FIG. 1.--PRODUCTION OF ILLUMINATING GAS.]
+
+Burn a piece of paper of about the size of the hand upon a clean
+porcelain plate, and this will serve to show the phenomena of
+carbonization and the formation of empyreumatic products under the action
+of heat. Under the burned paper there will be found a yellowish deposit
+which sticks to the fingers, and which consists of oil of paper produced
+by distillation. An idea of the production of illuminating gas through
+the distillation of coal may be easily given by means a single clay pipe.
+Upon filling the bowl of this with fragments of coal, closing the opening
+with clay, and, after the latter is dry, placing the bowl in a coal fire
+so that the stem shall project, gas will soon be observed issuing from,
+the latter, and, when lighted, will give a very bright flame. If the pipe
+seems to be a little too costly, recourse maybe had to a large piece of
+wrapping paper rolled into the form of a cornucopia, and held in the left
+hand by means of the pointed end. If, after an aperture has been made in
+this near the point, the base be lighted, the heat developed by the flame
+will produce a sort of distillation of the organic matter of the paper,
+and the empyreumatic and gaseous products will rise in the cone, and make
+their exit through the orifice, where they may be lighted with a match
+(Fig. 1). It goes without saying that this experiment lasts but a few
+seconds; but, as short as this period is, it is sufficient to give a
+demonstration of the production of illuminating gas through the
+distillation of organic matters. Care should be taken not to set anything
+on fire while performing it, and it is well to operate over a pavement,
+and far from any inflammable materials.
+
+
+ELASTICITY OF BODIES.
+
+[Illustration: FIG. 2.--EXPERIMENT ON THE ELASTICITY OF BODIES.]
+
+Mould a piece of fresh bread with the fingers so as to give it the size
+and shape shown in Fig. 2. If this object be placed upon a wooden table,
+and a hard blow be given it with the fist, it will be found impossible to
+put it permanently out of shape. However hard be the blow, the elastic
+material, although flattened for an instant, will always resume its
+original form. If the object be thrown on the floor with all one's might,
+the result will be the same; its elasticity will always cause it to
+spring back to its original form. The experiment will only succeed when
+the bread that is used is very fresh and soft.
+
+       *       *       *       *       *
+
+
+
+
+SCIENTIFIC AMUSEMENTS.
+
+
+_The Dance of the Electrified Puppets_.--We have already pointed out a
+means of obtaining electrical manifestations without recourse to a
+machine, and shall now describe a very easily performed experiment--the
+dance of the electrified puppets.
+
+[Illustration: FIG. 1.--DANCE OF THE ELECTRIFIED PUPPETS.]
+
+Procure a pane of glass about 10 inches in width and 14 in length, and
+support it between two large books, as shown in Fig. 1. The glass must be
+inserted in the books in such a way that it shall be an inch and a
+fraction above the surface of the table. Then, with a pair of scissors,
+cut out of a piece of tissue-paper a number of figures, such as men,
+women, clowns, frogs, etc. These little figures must not exceed
+three-quarters of an inch in length. We show some of actual size in Fig.
+1. They may be cut out of papers of different colors, so as to give
+variety to the scene. After they are prepared they are to be placed in
+the ball-room, that is to say, in the space between the books, glass, and
+table. They should be laid flat upon the table, and alongside of one
+another. Now rub the upper surface of the glass vigorously with a piece
+of silk or woolen, and, in a few instants, the figures will be attracted
+by the electricity, and suddenly stand up straight and jump up to the
+transparent ceiling of their ball-room. Then they will be repelled, and
+again attracted, and thus keep up a lively dance. When the rubbing is
+stopped, the dance continues spontaneously for some little time, and even
+the contact of the hand suffices to animate the figures. In order that
+this experiment shall prove a success, the glass used must be very dry,
+as well as the fabric with which it is rubbed. If the latter be warmed,
+the manifestation will be more rapid and energetic. Silk answers better
+than woolen.
+
+[Illustration: FIG. 2.--SILHOUETTE PORTRAITS.]
+
+_Silhouette Portraits_.--Take a large sheet of paper, black on one side
+and white on the other, and affix it to the wall, white surface outward,
+by means of pins or tacks. Place a very bright light upon the table, at a
+proper distance, and allow the person whose portrait it is desired to
+form to stand between it and the wall (Fig. 2). Then, with a pencil, draw
+the outlines of the shadow projected. While this is being done, it is
+very necessary that the subject shall keep perfectly immovable. When the
+outlines are sketched, remove the paper from the wall and cut out the
+portrait. After this, all that remains to be done is to turn the portrait
+over and paste it to a sheet of white paper. The silhouette is profiled
+in black, and if the operation be skillfully performed, the resemblance
+will be perfect.--_La Nature_.
+
+       *       *       *       *       *
+
+
+
+
+HOW TO BREAK A CORD WITH THE HANDS.
+
+
+Our readers have often seen grocers' clerks or employes of business
+houses break the string with which they had tied up a package, by seizing
+it with the hands, bringing the latter close together, and then suddenly
+separating them with a quick movement. If it be thought that this quick
+motion is sufficient, let any one try it, and he will merely cut his
+hands without breaking the string, provided the latter has some little
+strength. In order to succeed, the cord must be arranged in a certain
+manner, as we shall explain.
+
+[Illustration: MODE OF BREAKING A CORD WITH THE HANDS.]
+
+The cord to be broken is placed upon the left hand, and one of its ends
+is passed over the other in such a way as to form a cross, and the end
+forming the shorter part of the cross is wound around the fingers (it
+should be left long enough to make several turns). The other end is then
+turned back and wound around the right hand, so as to leave a space of
+about eighteen inches between the latter and the left hand. If these
+directions are properly followed, the string should have the form of a Y
+in the middle of the hand, as shown in the lower figure of the
+accompanying engraving.
+
+It is only necessary after this to close the hand, after seeing that the
+Y is very taut, and to seize the cord with the other hand, as shown in
+the upper figure. This done, the two hands are brought together and then
+suddenly separated so as to give a quick pull on the point of junction of
+the Y-shaped branches, which form a true knife. It will be readily seen
+that as the cord is broken suddenly the shock does not have time to
+transmit itself to the hands. This is an interesting demonstration of the
+principle of inertia.
+
+       *       *       *       *       *
+
+
+
+
+AN AQUATIC VELOCIPEDE FOR DUCK HUNTING.
+
+
+The curious apparatus that we represent in Fig. 1, from an old English
+engraving of 1823, is an aquatic velocipede which was utilized with
+success during the entire winter of 1822. An amateur employed it for
+hunting ducks upon the numerous streams of Lincolnshire, and, as it
+appears, obtained very good results from it. The device is very
+ingenious. It consists of three floats of from 1,800 to 2,000 cubic
+inches capacity, made of copper or tin plate. These are full of air, and
+must be perfectly tight. They are held together by arched iron rods, as
+shown in the cut, so as to form the three angles of an isosceles
+triangle. These rods are provided in the center with a saddle for the
+velocipedist to sit upon. The apparatus floats upon the water and
+sustains the hunter, whose feet are provided with quite short paddles, by
+means of which he navigates, and steers himself.
+
+[Illustration: FIG. 1.--AN AQUATIC VELOCIPEDE OF 1822.]
+
+The amusing engraving of this velocipede, which is mentioned under the
+name of the _aquatic tripod_, puts us in mind of another document of the
+same kind that we have seen in the gallery of prints of the National
+Library. It is a naively drawn lithograph representing a trial of
+velocipedes in the Luxembourg Garden, at Paris, in 1818. In Fig. 2 we
+give a reduced copy of it. It will be seen that in 1818 velocipedes were
+made of wood and were provided with two wheels--one in front, and the
+other behind. The propelling was done by alternately placing the feet on
+the ground.
+
+[Illustration: FIG. 2.--A TRIAL OF VELOCIPEDES IN 1818.]
+
+       *       *       *       *       *
+
+
+
+
+A SUNSHINE RECORDER.
+
+
+The apparatus is of simple construction. It consists of a glass sphere
+silvered inside and placed before the lens of a camera, the axis of the
+instrument being placed parallel to the polar axis of the earth. The
+whole arrangement will be readily understood by an inspection of Fig. 1.
+The light from the sun is reflected from the globe, and some of it,
+passing through the lens, forms an image on a piece of prepared paper
+within the camera. In consequence of the rotation of the earth, the image
+describes an arc of a circle on the paper, and when the sun is obscured,
+this arc is necessarily discontinuous. The image is not a point, but a
+line, and in certain relative positions of the sphere, lens, and paper,
+the line is radial and very thin, so that the obscuration of the sun for
+only one minute is indicated by a weakening of the image.
+
+[Illustration: FIG. 1.]
+
+In the actual apparatus the sphere is an ordinary round-bottomed flask
+about 95 mm. in diameter, and the lens a simple double convex lens of
+about 90 mm. focal length. The sensitive paper employed is the ordinary
+ferro-prussiate now so much used by engineers for copying tracings. This
+was selected in consequence of the ease with which the impression is
+fixed, for the paper merely requires to be washed in a stream of water
+for six minutes, no chemicals being necessary. When the paper is dry,
+radial lines containing between them angles of 15° are drawn from the
+center of the circular impression, and thus give the hour scale, the time
+of apparent noon being of course given by a line passing through the plan
+of the meridian. Fig. 2 is a copy of the record of June 27, 1884; in the
+morning the sun shone brightly, toward noon clouds began to form, and in
+the afternoon the sky was hazy. The field in which the instrument is
+placed is surrounded by trees, so the ends of the trace are cut off
+sharply by shadows.
+
+[Illustration: FIG. 2.]
+
+With the alteration of declination of the sun, the light entering the
+camera is reflected from different portions of the sphere, and an
+alteration of the position of the focus results. This may be corrected in
+three ways; by moving (1) the paper, (2) the lens, or (3) the sphere. In
+the present apparatus the first method has been adopted, and now the
+camera is about twice as long as it was in June. As a consequence, the
+circular image is enlarged, and the light therefore weakened, and that at
+a time of year when it can least be spared. If the focus is altered by
+moving the lens, the winter circle is small and the summer circle is much
+larger. This would perhaps be too much to the advantage of the winter
+sun. If, however, the lens and paper are maintained at a constant
+distance, and the sphere alone moved, the circles are more nearly of the
+same diameter throughout the year, the winter one still remaining the
+smallest. This seems, therefore, to be the most advantageous arrangement,
+and the one that will be adopted in future. It may be possible also to
+find positions for the sphere, lens, and paper such that the intensity of
+the image is a true measure of the intensity of the sun's light; at
+present, however, this has not been done, the want of sunlight and the
+press of official work having prevented the carrying out of the necessary
+experiments. A more sensitive paper might also be used with advantage,
+and in observatories where photographic processes are carried on daily
+there would be no difficulty on this score, but my principal object was
+to devise some economical instrument requiring only easy manipulation, so
+that at a considerable number of places the instruments might be set up,
+giving a more useful average of the duration of sunshine than can be
+obtained from only a few stations. The instrument also gives a record
+when the sun is shining through light clouds; in this case the image is
+somewhat blurred and naturally weakened, and it may be difficult or
+impossible to employ any scale for measuring the intensity under such
+conditions, but it must be remembered that, even when the sun is shining
+in this imperfect manner, it is really doing work on the vegetation of
+the earth, and deserves to be recorded.
+
+It may be well to say that the instrument is in no way protected. Some
+friends, whose opinion I highly value, urged me to patent it; but as I
+strongly hold the view that the work of all students of science should be
+given freely to the world, the apparatus was described at the Physical
+Society a few hours after the advice was given, lest the greed of filthy
+lucre should, on further deliberation, cause me to act contrary to my
+principles.--_Herbert McLeod, Nature_.
+
+       *       *       *       *       *
+
+
+
+
+SKELETON OF A BEAR FOUND IN A CAVE IN STYRIA, AUSTRIA.
+
+
+In the limestone mountains of the Austrian Alpine countries, numerous
+large caverns and caves are found, some of which are several miles long.
+They have been formed by the raising, lowering, and sliding of the layers
+of sand, or washed out by the stream.
+
+In one of these caverns near Peggau, in Styria, Austria, the skeleton of
+a bear (_Ursus Spelaeus_) and the skull of another bear of the same kind
+were found, both of which are shown in the annexed cut taken from the
+_Illustrirte Zeitung_, the detached skull being placed on a board. The
+place in which these bones were found had never been reached before, as
+the skeleton was covered by a layer, from four to six inches thick, of
+stalagmites, which in turn rested on a layer of pieces or chips of bones
+and carbonate of lime, sand, etc. The bones of the skeleton were
+scattered over a space about eight square yards, and it required several
+days' work to remove the layers from the bones by means of a mallet and
+chisel and to give the bones, etc., a presentable appearance.
+
+[Illustration: SKELETON OF A BEAR FOUND IN A CAVE IN STYRIA,
+AUSTRIA.]
+
+The skull on the board is of especial interest on account of the
+beautiful crystals of calcareous spar, which are from 1/10 to 1/4 of an
+inch long, and are formed on the inner sides of the skull. The skull is
+5-1/2 in. wide between the fangs and 6-3/5 in. wide at the forehead,
+whereas the skull of the skeleton is only 3-9/10 in. wide at the fangs
+and 5-1/10 in. wide at the forehead. The skull of the skeleton is 22 in.
+long. The small white object on the board supporting the detached skull
+represents the skull of an ordinary cat, thus giving an idea of the
+enormous size of the bear's skull. The skeleton is 9 ft. 8 in. high, and
+is one of the largest and most complete that has been found.
+
+       *       *       *       *       *
+
+
+
+
+THE HARDNESS OF METALS.
+
+
+The German _Verein zur Bedförderung des Gewerbefleisses_ offers the
+following, among other prizes, for essays on technical subjects: One
+thousand marks _(£50)_ for a comparative examination of the various
+methods hitherto used for determination of the hardness of metals, with
+an exposition of their sources of error and limits of accuracy. It is
+stated, as a reason for offering the prize, that the methods for making
+the required tests are but yet little developed, and that no thorough
+comparison has yet been made of the various methods. The hardness of
+metals and alloys being a very important factor in several processes, a
+really good method of determination is highly desirable. Three thousand
+marks (£150) for the best essay on the resistance to pressure of iron
+work in buildings, at increased temperatures. It appears that after a
+certain fire in a manufactory at Berlin, the police authorities issued
+notices concerning the use of cast-iron columns in high buildings, and
+that these notices encountered great opposition in many quarters, as it
+was considered that neither practice nor theory had yet shown any proof
+that cast iron is less trustworthy than wrought iron in cases of fire.
+
+       *       *       *       *       *
+
+A brilliant black varnish for iron, stone, or wood can be made by
+thoroughly incorporating ivory black with common shellac varnish. The
+mixture should be laid on very thin. But ordinary coal tar varnish will
+serve the same purpose in most cases quite as well, and it is not nearly
+so expensive.
+
+       *       *       *       *       *
+
+
+
+
+STEAM YACHTS.
+
+
+Although the racing of steam yachts as a recognized sport has not made
+the progress that was at one time expected, yet the owner and crew of a
+crack vessel will take as much interest in her performance as those
+belonging to a sailing yacht, and hate to be passed quite as badly. In
+this way many informal matches come off, and some of these are for
+considerable distances. The _Field_ contains a notice of a run recently
+made from Plymouth Breakwater to Gibraltar, by the Juno, owned by Mr.
+Frank Millan, and the Queen of Palmyra, in which the former beat the
+latter by only five minutes. The time occupied was four days twenty
+hours, a fair, though not extraordinary, performance for vessels of this
+size. The Juno has always been considered a slow boat, but has been much
+improved lately by new machinery, which has been put in her by Messrs.
+Day, Summers & Co. Her best performance on the run was 235 knots in 21¾
+hours. The Marchesa, Mr. C.T. Kettlewell, started from Plymouth on the
+23d of last December, and made the run to Gibraltar in four days
+seventeen hours; while the Amy, starting on December 12, was four days
+thirteen hours from Cowes to Gibraltar.
+
+       *       *       *       *       *
+
+
+A catalogue, containing brief notices of many important scientific papers
+heretofore published in the SUPPLEMENT, may be had gratis at this office.
+
+
+       *       *       *       *       *
+
+
+
+
+THE SCIENTIFIC AMERICAN SUPPLEMENT.
+
+PUBLISHED WEEKLY.
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+1876, can be had. Price, 10 cents each.
+
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+
+MUNN & CO., Publishers,
+
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+
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+       *       *       *       *       *
+
+
+PATENTS.
+
+In connection with the SCIENTIFIC AMERICAN, Messrs. MUNN & Co. are
+Solicitors of American and Foreign Patents, have had 40 years'
+experience, and now have the largest establishment in the world. Patents
+are obtained on the best terms.
+
+A special notice is made in the SCIENTIFIC AMERICAN of all
+Inventions patented through this Agency, with the name and residence of
+the Patentee. By the immense circulation thus given, public attention is
+directed to the merits of the new patent, and sales or introduction often
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+
+Any person who has made a new discovery or invention can ascertain, free
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+
+End of the Project Gutenberg EBook of Scientific American Supplement, No.
+483, April 4, 1885, by Various
+
+*** END OF THE PROJECT GUTENBERG EBOOK 14097 ***