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+<title>The Project Gutenberg eBook of Scientific American
+Supplement, APRIL 4, 1885</title>
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+<div>*** START OF THE PROJECT GUTENBERG EBOOK 14097 ***</div>
+
+<p class="ctr"><a href="./images/1a.png"><img src=
+"./images/1a_th.jpg" alt="Title"></a></p>
+
+<h1>SCIENTIFIC AMERICAN SUPPLEMENT NO. 483</h1>
+
+<h2>NEW YORK, APRIL 4, 1885</h2>
+
+<h4>Scientific American Supplement. Vol. XIX, No. 483.</h4>
+
+<h4>Scientific American established 1845</h4>
+
+<h4>Scientific American Supplement, $5 a year.</h4>
+
+<h4>Scientific American and Supplement, $7 a year.</h4>
+
+<hr>
+<table summary="Contents" border="0" cellspacing="5">
+<tr>
+<th colspan="2">TABLE OF CONTENTS.</th>
+</tr>
+
+<tr>
+<td valign="top">I.</td>
+<td><a href="#1">CHEMISTRY AND METALLURGY.&mdash;The Determination
+of Graphite in Minerals.&mdash;By J.B. MACKINTOSH.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#2">Sulphocyanide of Potassium.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#3">Sugar Nitro-glycerine.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#4">On Remelting of Cast Iron.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#5">The Hardness of Metals.</a> </td>
+</tr>
+
+<tr>
+<td valign="top">II.</td>
+<td><a href="#6">ENGINEERING, ETC.&mdash;The Jet Ventilator. 4
+figures.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#7">Feeding Boilers at the Bottom. 2 figures.</a>
+</td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#8">The Honigmann Fireless Engine.&mdash;The fireless
+working of steam engines by means of a solution of hydrate of
+soda.&mdash;With several figures and diagrams.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#9">Simple Methods of Calculating Stress in
+Girders.&mdash;By CH. LEAN.&mdash;With full page of
+illustrations.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#10">A Spring Motor.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#11">Steam Yachts.</a> </td>
+</tr>
+
+<tr>
+<td valign="top">III.</td>
+<td><a href="#12">TECHNOLOGY.&mdash;Foucault's Apparatus for
+Manufacturing Illuminating Gas and Hydrogen. 2 figures.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#13">The Circle Divider.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#14">Soluble Glass.&mdash;Process of
+manufacture.&mdash;Use.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#15">Iron Printing and Microscopic
+Photography.&mdash;Formulas for printing solutions.&mdash;Compound
+negatives.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#16">Practical Directions for Making Lantern
+Transparencies.&mdash;By T.N. ARMSTRONG.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#17">Casting Chilled Car Wheels. 6 figures.</a> </td>
+</tr>
+
+<tr>
+<td valign="top">IV.</td>
+<td><a href="#18">ELECTRICITY, ETC.&mdash;Electricity and
+Prestidigitation. 2 figures.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#19">Portable Electric Safety Lamp. 6 figures.</a>
+</td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#20">The Electric Discharge and Spark Photographed
+Directly without an Objective. 6 engravings.</a> </td>
+</tr>
+
+<tr>
+<td valign="top">V.</td>
+<td><a href="#21">PHYSICS, ETC.&mdash;The True Constant of
+Gravity.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#22">Origin of Thunder Storms.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#23">Physics without Apparatus.&mdash;Manufacture of
+illuminating gas.&mdash;Elasticity of bodies. 2 figures.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#24">Scientific Amusements.&mdash;Dance of electrified
+puppets.&mdash;Silhouette portraits. 2 figures.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#25">A Sunshine Recorder. 2 figures.</a> </td>
+</tr>
+
+<tr>
+<td valign="top">VI.</td>
+<td><a href="#26">MEDICINE, HYGIENE, ETC.&mdash;How Cholera is
+Spread.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#27">Sulphurous Acid and Sulphide of Carbon as
+Disinfecting Agents.&mdash;Methods of burning the same.</a> </td>
+</tr>
+
+<tr>
+<td valign="top">VII.</td>
+<td><a href="#28">MISCELLANEOUS.&mdash;Improvised Toys.&mdash;With
+numerous illustrations.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#29">The &AElig;olian Harp.&mdash;Kircher's harp, made
+in 1558.&mdash;Frost and Kastner's harp.&mdash;Manner of making the
+harps. 4 figures.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#30">How to Break a Cord with the Hands. 1 figure.</a>
+</td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#31">An Aquatic Velocipede for Duck Hunting. 2
+engravings.</a> </td>
+</tr>
+
+<tr>
+<td></td>
+<td><a href="#32">Skeleton of a Bear Found in a Cave in Styria,
+Austria.</a> </td>
+</tr>
+
+<tr>
+<td valign="top">VIII.</td>
+<td><a href="#33">BIOGRAPHY.&mdash;Theodor Billroth, Prof, of
+Surgery at Vienna.&mdash;With portrait.</a> </td>
+</tr>
+</table>
+
+<hr>
+<h2>ACKNOWLEDGMENT.</h2>
+
+<p>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 <i>La Nature</i>.</p>
+
+<hr>
+<a name="33"></a>
+
+<h2>THEODOR BILLROTH, PROFESSOR OF SURGERY AT VIENNA.</h2>
+
+<p>The well known surgeon, Theodor Billroth, was born on the island
+of R&uuml;gen 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 Sch&ouml;nlein, who were Billroth's instructors
+at Greifswald, G&ouml;ttingen, 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.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/1b.png"><img src=
+"./images/1b_th.jpg" alt=" THEODOR BILLROTH."></a></p>
+
+<p class="ctr">THEODOR BILLROTH.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>The accompanying portrait is from the <i>Illustrirte
+Zeitung.</i></p>
+
+<hr>
+<a name="26"></a>
+
+<h2>HOW CHOLERA IS SPREAD.</h2>
+
+<p>DR. JOHN C. PETERS, of this city, in a recent contribution to
+the <i>Medical Record</i>, gives the following interesting
+particulars:</p>
+
+<p>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.</p>
+
+<p>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 <i>zadig</i>, or canal, runs
+through Damietta from one branch of the Nile to another, and this
+is the principal source of the water supply.</p>
+
+<p>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.</p>
+
+<p>When the pestilence had been let out <i>en masse</i>, 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.</p>
+
+<p>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 <i>pozzis</i>, 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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<hr>
+<p>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.</p>
+
+<hr>
+<a name="27"></a>
+
+<h2>SULPHUROUS ACID AND SULPHIDE OF CARBON.</h2>
+
+<p>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 <i>Journal de Pharmacie et de Chimie</i>
+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.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/2a.png"><img src=
+"./images/2a_th.jpg" alt=" FIG. 1.&mdash;BURNER FOR SULPHUR.">
+</a></p>
+
+<p class="ctr">FIG. 1.&mdash;BURNER FOR SULPHUR.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/2b.png"><img src=
+"./images/2b_th.jpg" alt=
+" FIG. 2.&mdash;CKIANDI BEY'S APPARATUS FOR BURNING CARBON SULPHIDE.">
+</a></p>
+
+<p class="ctr">FIG. 2.&mdash;CKIANDI BEY'S APPARATUS FOR BURNING
+CARBON SULPHIDE.</p>
+
+<p>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 <i>modus operandi</i> 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.</p>
+
+<p>It will be seen, then, that for a room of 3,530 cubic feet
+capacity the cost would be $5.00 or $2.50.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/2c.png"><img src=
+"./images/2c_th.jpg" alt=
+" FIG. 3.&mdash;SECTION OF THE APPARATUS."></a></p>
+
+<p class="ctr">FIG. 3.&mdash;SECTION OF THE APPARATUS.</p>
+
+<p>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 <i>aa</i>. This done, we fill the external vessel with water
+up to the level <i>bb</i>. 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
+<i>a'a',</i> 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.</p>
+
+<p>The combustion may be retarded or quickened at will by causing
+the level <i>bb</i> of the water to rise or lower.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.&mdash;<i>La
+Nature</i>.</p>
+
+<hr>
+<a name="1"></a>
+
+<h2>THE DETERMINATION OF GRAPHITE IN MINERALS.</h2>
+
+<h3>By J.B. MACKINTOSH.</h3>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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:</p>
+
+<pre>
+New Method.       Combustion in Oxygen, Weighing CO&#8322;.
+  15.51                         15.54
+</pre>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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,<a name="FNanchor_1"></a><a href=
+"#Footnote_1"><sup>1</sup></a> 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.&mdash;<i>Sch. Mines
+Quarterly.</i></p>
+
+<a name="Footnote_1"></a><a href="#FNanchor_1">[1]</a>
+
+<div class="note">Schloffel, Zeitschrift der K.K. geolog.
+Reichanstalt, 1866, p. 126</div>
+
+<hr>
+<a name="2"></a>
+
+<h2>SULPHOCYANIDE OF POTASSIUM.</h2>
+
+<p>The elements of cyanogen, combined with sulphur, form a salt
+radical, sulphocyanogen, C<sub>2</sub>NS<sub>2</sub>, 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.</p>
+
+<p>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:</p>
+
+<pre>
+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).
+</pre>
+
+<p><i>Ferrocyanide of Potassium</i>&mdash;K<sub>2</sub>Cfy+3HO, or
+K<sub>2</sub>C<sub>8</sub>N<sub>3</sub>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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<sub>2</sub>Cfy)+Cl=K<sub>3</sub>Cfy<sub>2</sub>+KCl.</p>
+
+<p>The radical ferridcyanogen, isomeric<a name="FNanchor_2"></a><a
+href="#Footnote_2"><sup>2</sup></a> 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<sub>3</sub>Cfdy.</p>
+
+<p>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.</p>
+
+<p>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<sub>2</sub>Cfy + 2(Fe<sub>2</sub>O<sub>3</sub>3NO<sub>3</sub>) =
+Fe<sub>4</sub>Cfy<sub>3</sub> + 6(KO,NO<sub>5</sub>). 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.</p>
+
+<p>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<sub>3</sub>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.&mdash;<i>E., Photo. Times</i>.</p>
+
+<a name="Footnote_2"></a><a href="#FNanchor_2">[2]</a>
+
+<div class="note">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.</div>
+
+<hr>
+<a name="12"></a>
+
+<h2>FOUCAULT'S APPARATUS FOR MANUFACTURING ILLUMINATING GAS AND
+HYDROGEN.</h2>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/3a.png"><img src=
+"./images/3a_th.jpg" alt=
+" FIG. 1.&mdash;FOUCAULT'S GAS APPARATUS."></a></p>
+
+<p class="ctr">FIG. 1.&mdash;FOUCAULT'S GAS APPARATUS.</p>
+
+<p>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.</p>
+
+<p>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 <i>bis</i>, 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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/3b.png"><img src=
+"./images/3b_th.jpg" alt=" FIG. 2.&mdash;SECTION."></a></p>
+
+<p class="ctr">FIG. 2.&mdash;SECTION.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.&mdash;<i>Chronique Industrielle.</i></p>
+
+<hr>
+<a name="3"></a>
+
+<h2>SUGAR NITRO-GLYCERINE.</h2>
+
+<p>A new explosive has been discovered by M. Roca, a French
+engineer, who communicates an account of it to <i>Le G&eacute;nie
+Civil</i>. 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.</p>
+
+<hr>
+<a name="13"></a>
+
+<h2>THE CIRCLE-DIVIDER.</h2>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/4a.png"><img src=
+"./images/4a_th.jpg" alt=
+" FIG. 1.&mdash;MODE OF USING THE CIRCLE DIVIDER. "></a></p>
+
+<p class="ctr">FIG. 1.&mdash;MODE OF USING THE CIRCLE DIVIDER.</p>
+
+<p>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&mdash;</p>
+
+<p>Circumf. c / Circumf. C = r / R</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/4b.png"><img src=
+"./images/4b_th.jpg" alt=" FIG. 2.&mdash;THE CIRCLE DIVIDER. ">
+</a></p>
+
+<p class="ctr">FIG. 2.&mdash;THE CIRCLE DIVIDER.</p>
+
+<hr>
+<a name="14"></a>
+
+<h2>SOLUBLE GLASS.</h2>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>The following ingredients are heated in a reverberatory furnace
+until fusion becomes quieted: 1,260 pounds white sand, 660 pounds
+potash of 78&deg;. 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&deg; to 35&deg; 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.</p>
+
+<p>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.</p>
+
+<p>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&deg;, 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.</p>
+
+<p>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.</p>
+
+<p>To apply soluble glass for the preservation of buildings and
+monuments of porous materials, take a solution of silicate of
+potash of 35&deg; 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&deg; to 9&deg; Baume; for soft
+stones with coarse grit, 5&deg; to 7&deg;; for calcareous stones of
+soft texture, 6&deg; to 7&deg;. The last coating should always be
+applied with a more dilute solution of 3&deg; to 4&deg; only.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>The colors used for this style of painting are zinc white, green
+oxide of chrome, cobalt green, chromate of lead, colcothar, ochers,
+and ultramarine.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.&mdash;<i>Glassware Reporter.</i></p>
+
+<hr>
+<a name="6"></a>
+
+<h2>THE JET VENTILATOR.</h2>
+
+<p class="ctr"><a href="./images/4c.png"><img src=
+"./images/4c_th.jpg" alt=" KORTING'S JET VENTILATOR."></a></p>
+
+<p class="ctr">KORTING'S JET VENTILATOR.</p>
+
+<p>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.</p>
+
+<p>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.--<i>Mech. World</i>.</p>
+
+<hr>
+<a name="4"></a>
+
+<h2>ON REMELTING OF CAST IRON.</h2>
+
+<p>From trials conducted by Ledebur, it appears that cast iron is
+rendered suitable for foundry purposes&mdash;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&mdash;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.</p>
+
+<p>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.&mdash;<i>Eisenhuettentechnik.</i></p>
+
+<hr>
+<a name="7"></a>
+
+<h2>FEEDING BOILERS AT THE BOTTOM.</h2>
+
+<p>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&mdash;no matter what part&mdash;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.</p>
+
+<p>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.</p>
+
+<p>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 <i>how</i> 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.</p>
+
+<p>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 <i>how</i> 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 <i>cannot</i> rise until it has become heated, for there
+is a great difference between the specific gravity of water at
+60&deg;, or even 212&deg; Fahr., and water at 324&deg;.
+Consequently, it "hugs" the bottom of the boiler, and flows toward
+the <i>front</i> end, or hottest portion of the shell. Now let us
+examine the effect which it produces.</p>
+
+<p>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 <i>one ton</i> per square inch of
+section for every 15 degrees. That is, suppose we fix a piece of
+iron, a strip of boilerplate, for instance, &frac14; 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.</p>
+
+<p class="ctr"><a href="./images/5a.png"><img src=
+"./images/5a_th.jpg" alt=" FIG. 1"></a></p>
+
+<p class="ctr">FIG. 1</p>
+
+<p>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&deg; Fahr. A large
+quantity of cold water, often at a temperature as low as 50&deg;
+Fahr., is introduced through an opening in the bottom, and flows
+along over these heated plates. If it could produce its <i>full</i>
+effect at once, the contraction caused thereby would bring a stress
+of 300 &divide; 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 <i>can</i> act to such an extent that we have known it
+to rupture the plates of a new boiler through the seams on the
+bottom <i>no less than three times in less than six weeks</i> after
+the boilers were started up.</p>
+
+<p>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 <i>stays
+there</i>, 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 <i>its</i> 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&deg; Fahr., while the water on top, above
+the tubes, was sufficiently hot to scald; and they will remain in
+such a condition for hours.</p>
+
+<p class="ctr"><a href="./images/5b.png"><img src=
+"./images/5b_th.jpg" alt=" FIG. 2."></a></p>
+
+<p class="ctr">FIG. 2.</p>
+
+<p>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
+<i>p</i> 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.&mdash;<i>The
+Locomotive</i>.</p>
+
+<hr>
+<a name="15"></a>
+
+<h3>[MICROSCOPICAL JOURNAL.]</h3>
+
+<h2>IRON PRINTING AND MICROSCOPIC PHOTOGRAPHY.</h2>
+
+<h3>By C.M. VORCE, F.R.M.S.</h3>
+
+<h3>I. FORMULAS FOR PRINTING SOLUTIONS.</h3>
+
+<p><i>Blue Prints</i>.&mdash;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.</p>
+
+<p>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&times;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.</p>
+
+<p><i>Black Prints</i>.&mdash;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.</p>
+
+<p>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.</p>
+
+<p><i>Chief Proof Solution</i>.&mdash;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.</p>
+
+<p>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.</p>
+
+<h3>II. COMPOUND NEGATIVES.</h3>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<hr>
+<a name="16"></a>
+
+<h2>PRACTICAL DIRECTIONS FOR MAKING LANTERN TRANSPARENCIES.<a name=
+"FNanchor_5"></a><a href="#Footnote_5"><sup>5</sup></a></h2>
+
+<h3>By T.N. ARMSTRONG.</h3>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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:</p>
+
+<p>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:</p>
+
+<pre>
+ Alcohol.              1 ounce.
+ Bromide of cadmium.  32 grains.
+ Hydrochloric acid.    8 drops.
+</pre>
+
+<p>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
+&frac12;-plates or four dozen 3&frac14; by 3&frac14;, 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&mdash;which it will do in about 5
+minutes&mdash;take of the bromized solution &frac12; 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.</p>
+
+<p>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, <i>not acid,</i> 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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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 3&frac14; by 3&frac14; 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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>Let me deal with the latter point first. You will at once
+understand that a negative whose size bears a proportion similar to
+3&frac14; by 3&frac14; 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 disk&frac14; by 3&frac14;,
+recourse must be had to a sort of squaring of the negative. Now,
+here I have a negative 7&frac14; by 4&frac12;, 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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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&mdash;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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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 7&frac14; by 4&frac12;, 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.</p>
+
+<p>The formula for development is as follows:</p>
+
+<pre>
+Pyro.                96 grains.
+Methylated spirits.   1 ounce.
+Bromide of potash.   12 grams.
+Water.                1 ounce.
+Carbonate ammonia.   60 grains.
+Water.                1 ounce.
+</pre>
+
+<p>Mix 30 drops pyro with from 30 to 60 drops bromide, then add 2
+drachms ammonia solution and 2 drachms of water.</p>
+
+<p>I find a thin negative requires a slow development, and so gain
+contrast; while hard negatives are best over-exposed and quickly
+developed.</p>
+
+<p>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&mdash;this is often the case if the negative has been thinner
+in some parts than others, through uneven coating of the
+plate&mdash;the picture need not be discarded as a failure, for I
+will explain to you later on how to overcome this difficulty.</p>
+
+<p>Fix the plate in hypo&mdash;the fixing takes place very
+quickly&mdash;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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<a name="Footnote_5"></a><a href="#FNanchor_5">[5]</a>
+
+<div class="note">Abstract of a paper communicated to the Glasgow
+and West of Scotland Amateur Photographic Association.&mdash;From
+the <i>Photographic News</i>.</div>
+
+<hr>
+<a name="8"></a>
+
+<h2>THE HONIGMANN FIRELESS ENGINE.</h2>
+
+<p>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&mdash;NaO
+HO&mdash;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:</p>
+
+<pre>
++---------------------+------------------+----------------------
+|                     | 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   "
++---------------------+------------------+----------------------
+</pre>
+
+<p><i>Experiment No. 15</i>.<a name="FNanchor_3"></a><a href=
+"#Footnote_3"><sup>3</sup></a>&mdash;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.</p>
+
+<p class="ctr"><a href="./images/7a.png"><img src=
+"./images/7a_th.jpg" alt=" FIG. 1."></a></p>
+
+<p class="ctr">FIG. 1.</p>
+
+<p class="ctr"><a href="./images/7b.png"><img src=
+"./images/7b_th.jpg" alt=" FIG. 2."></a></p>
+
+<p class="ctr">FIG. 2.</p>
+
+<p>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 <i>a b c d</i>, 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&mdash;Figs. 5 and
+6&mdash;are worked with a closed soda vessel in which a pressure of
+1/2 to 1&frac12; 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.</p>
+
+<p class="ctr"><a href="./images/7c.png"><img src=
+"./images/7c_th.jpg" alt=" FIG. 3."></a></p>
+
+<p class="ctr">FIG. 3.</p>
+
+<p class="ctr"><a href="./images/7d.png"><img src=
+"./images/7d_th.jpg" alt=" FIG. 4."></a></p>
+
+<p class="ctr">FIG. 4.</p>
+
+<p>TABLE.&mdash;100 <i>kilogs. Soda Lye containing 20 parts Water
+with a corresponding boiling point of 220 deg. Cent. absorb Steam
+as follows</i>:</p>
+
+<pre>
++----------------------------------+--------------+---------------+
+|Final pressure in condenser.      |              |               |
++----------------------------------+Pressure in   |Corresponding  |
+|  0    | &frac12; atm. | 1 atm. | 1&frac12; 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   "     |
+|22&frac12; "  | 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   "     |
++-------+--------+--------+--------+--------------+---------------+
+</pre>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/7e.png"><img src=
+"./images/7e_th.jpg" alt=" FIG. 5"></a></p>
+
+<p class="ctr">FIG. 5</p>
+
+<p class="ctr"><a href="./images/7f.png"><img src=
+"./images/7f_th.jpg" alt=" FIG. 6"></a></p>
+
+<p class="ctr">FIG. 6</p>
+
+<p>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<a name="FNanchor_4"></a><a href=
+"#Footnote_4"><sup>4</sup></a> 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:</p>
+
+<p>Wurselen, Dec. 23, 1884.</p>
+
+<p class="ctr"><a href="./images/8a.png"><img src=
+"./images/8a_th.jpg" alt=
+" DIAGRAMS FOR THE CALCULATION OF STRESSES IN BOWSTRING GIRDERS.">
+</a></p>
+
+<p class="ctr">DIAGRAMS FOR THE CALCULATION OF STRESSES IN
+BOWSTRING GIRDERS.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/9a.png"><img src=
+"./images/9a_th.jpg" alt=" FIG. 7."></a></p>
+
+<p class="ctr">FIG. 7.</p>
+
+<p class="ctr"><a href="./images/9b.png"><img src=
+"./images/9b_th.jpg" alt=" FIG. 8."></a></p>
+
+<p class="ctr">FIG. 8.</p>
+
+<p>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>i.e.</i>, 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 4&frac12; to 5 cubic meters soda lye was 6,500
+liters.</p>
+
+<p>Another certificate concerning the tramway engine illustrated in
+Figs. 5 and 6 is of equal interest, and runs as follows:</p>
+
+<p>Aix la Chapelle, Jan. 5, 1885.</p>
+
+<p>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 10&frac12; hours, <i>viz.</i>, 5&frac12; 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</p>
+
+<pre>
+Of about 1 in 30 in 400 meter length.
+   "     1  " 45  " 250    "
+   "     1  " 72  " 350    "
+</pre>
+
+<p>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 8&frac12; 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 10&frac12; 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 10&frac12; hours'
+service, which corresponds to a 6.6 fold evaporation.</p>
+
+<p>(Signed) M.F. GUTERMUTH,</p>
+
+<p>Assistant for Engineering at the Technical High School.</p>
+
+<p>HASELMANN,</p>
+
+<p>Manager of the Aix la Chapelle-Burtscheid Tramway.</p>
+
+<p>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.</p>
+
+<p>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&mdash;if only by converting some of their old
+engines into those of the fireless system&mdash;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.&mdash;<i>E., in The Engineer</i>.</p>
+
+<a name="Footnote_3"></a><a href="#FNanchor_3">[3]</a>
+
+<div class="note">Zeitschrift d. Vereins Deutscher Ingenieur, 1883,
+p. 730; 1884, p. 69.</div>
+
+<a name="Footnote_4"></a><a href="#FNanchor_4">[4]</a>
+
+<div class="note">Z.d.V.D.I., 1884, p. 978</div>
+
+<hr>
+<a name="9"></a>
+
+<h2>SIMPLE METHODS OF CALCULATING STRESSES IN GIRDERS.</h2>
+
+<h3>By CHARLES LEAN, M. Inst. C.E.</h3>
+
+<p><i>Bowstring Girders.</i>&mdash;Having had occasion to get out
+the stresses in girders of the bowstring form, the author was not
+satisfied with the common formul&aelig; 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 formul&aelig; 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:</p>
+
+<p>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&mdash;Fig.
+1&mdash;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=</p>
+
+<pre>
+ _                                                                _
+| Stress caused by diagonals   Length of right   Depth of parallel |
+|      leaning to left.           vertical.       flanged girder.  |
+|                                                                  | +
+|_           15.75            &times;       1/4.5     &times;        10       _|
+ _                                                                _
+| Stress caused by diagonals   Length of ver-    Depth of parallel |
+|     leaning to right.        tical to left.     flanged girder.  |
+|                                                                  |
+|_           24               &times;       1/8       &times;        10       _|
+
+= 65; and the vertical component =
+
+   Horizontal component.            Length of bay.
+
+          65               &times;       1/10   &times; (8.0 - 4.5) = 22.75.
+</pre>
+
+<p>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&mdash;see Fig. 2&mdash;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 formul&aelig;: 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
+formul&aelig; 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:</p>
+
+<pre>
+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.
+    w&sup1;= live load per bay of girder.
+    W = total load per bay of girder = w + w&sup1;.
+
+Then: S/B = N.
+
+Bottom Flange. WNS/8D = maximum stress throughout.          (1)
+
+Top Flange.--In any bay the maximum stress =
+
++ WNS/8D &times; L/B = + WLN&sup2;/8D                                  (2)
+
+<i>Verticals.</i>--The maximum stress = -W.                        (3)
+
+<i>Diagonals.</i>--The maximum stress is
+
+&plusmn; w&sup1;lS/16DB = &plusmn; w&sup1;lN/16D                                    (4)
+</pre>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<pre>
+FIG. 1B.
+_______________________________________________________________________________
+                                            |
+          Top Flange Stresses.              |      Stresses in Diagonals.
+                               Hor.    Ver. |
+                                            |
+C= 31.5  &times; 10/4.5  =         +70.00 = 31.50 |a = 70   -65         =+5.00 = 2.25
+                                            |
+   15.75 &times; 10/4.5  = 35                     |b =  "     "         =-5.00 = 4.00
+                          \                 |
+D                          &gt; +65.00 = 22.75 |c = 65   -58.33-5    =+1.67 = 1.33
+                          /                 |
+   24    &times; 10/8    = 30                     |d =  "      "   "    =-1.67 = 1.75
+                          \                 |
+E                          &gt; +58.33 = 14.58 |e = 58.33-55.83-1.67 =+ .83 =  .88
+                          /                 |
+   29.75 &times; 10/10.5 = 28.33                  |f =   "     "     "  =- .83 = 1.01
+                          \                 |
+F                          &gt; +55.83 =  8.37 |g = 55.83-54.50- .83 =+ .50 =  .59
+                          /                 |
+   33    &times; 10/12   = 27.5                   |h =   "     "     "  =- .50 =  .61
+                          \                 |
+G                          &gt; +54.50 =  2.72 |i = 54.50-53.67- .50 =+ .33 =  .43
+                          /                 |
+   33.75 &times; 10/12.5 = 27                     |j =   "     "     "  =- .33 =  .41
+                          \                 |
+H                          &gt; +53.67 =  2.68 |k = 53.67-53.09- .33 =+ .24 =  .28
+                          /                 |
+   32    &times; 10/12   = 26.67                  |l =   "     "     "  =- .24 =  .24
+                          \                 |
+I                          &gt; +53.09 =  7.97 |m = 53.09-52.67- .24 =+ .18 =  .20
+                          /                 |
+   27.75 &times; 10/10.5 = 26.42                  |n =   "     "     "  =+ .18 =  .16
+                          \                 |
+J                          &gt; +52.67 = 13.17 |o = 52.67-52.36- .18 =+ .13 =  .11
+                          /                 |
+   21    &times; 10/8    = 26.25                  |p =   "     "     "  =- .13 =  .06
+                          \                 |
+K                          &gt; +52.36 = 18.33 |
+                          /                 |
+   11.75 &times; 10/4.5  = 26.11                  |
+                                            |
+L= 23.5  &times; 10/4.5  =         +52.22 = 23.50 |
+____________________________________________|___________________________________
+                                            |
+      <i>Bottom Flange Stresses.</i>        |    <i>Stresses in Verticals.</i>
+                                            |
+                          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              |
+____________________________________________|____________________________________
+</pre>
+
+<p>&mdash;<i>The Engineer.</i></p>
+
+<hr>
+<a name="10"></a>
+
+<h2>A SPRING MOTOR.</h2>
+
+<p>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.</p>
+
+<p>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.&mdash;<i>Phil. Inquirer</i>.</p>
+
+<hr>
+<a name="17"></a>
+
+<h2>CASTING CHILLED CAR WHEELS.</h2>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/10a.png"><img src=
+"./images/10a_th.jpg" alt=" CASTING OF CAR WHEELS."></a></p>
+
+<p class="ctr">CASTING OF CAR WHEELS.</p>
+
+<p>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.&mdash;<i>Jour. Railway App.</i></p>
+
+<hr>
+<a name="18"></a>
+
+<h2>ELECTRICITY AND PRESTIDIGITATION.</h2>
+
+<p>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
+<i>supernatural</i>, because of their powerlessness to find a
+satisfactory explanation of them.</p>
+
+<p class="ctr"><a href="./images/10b.png"><img src=
+"./images/10b_th.jpg" alt=
+" FIG. 1.&mdash;RAPPING AND TALKING TABLE. "></a></p>
+
+<p class="ctr">FIG. 1.&mdash;RAPPING AND TALKING TABLE.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/10c.png"><img src=
+"./images/10c_th.jpg" alt=" FIG. 2.&mdash;ELECTRIC INSECTS.">
+</a></p>
+
+<p class="ctr">FIG. 2.&mdash;ELECTRIC INSECTS.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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, <i>c</i>, which
+is bent at right angles at its upper part, and in front of which is
+placed a small iron disk, <i>b</i>, 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.</p>
+
+<hr>
+<a name="19"></a>
+
+<h2>PORTABLE ELECTRIC SAFETY LAMPS.</h2>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/11a.png"><img src=
+"./images/11a_th.jpg" alt=" FIG. 1.&mdash;ELEVATION (Scale 1/25).">
+</a></p>
+
+<p class="ctr">FIG. 1.&mdash;ELEVATION (Scale 1/25).</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/11b.png"><img src=
+"./images/11b_th.jpg" alt=" FIG. 2.&mdash;PLAN (Scale 1/25).">
+</a></p>
+
+<p class="ctr">FIG. 2.&mdash;PLAN (Scale 1/25).</p>
+
+<p><i>General Description</i>.&mdash;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.</p>
+
+<p class="ctr"><a href="./images/11c.png"><img src=
+"./images/11c_th.jpg" alt=
+" FIG. 3.&mdash;HAND LANTERN (Scale 1/4)."></a></p>
+
+<p class="ctr">FIG. 3.&mdash;HAND LANTERN (Scale 1/4).</p>
+
+<p><i>Maneuver of the Apparatus</i>.&mdash;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.</p>
+
+<p class="ctr"><a href="./images/11d.png"><img src=
+"./images/11d_th.jpg" alt=
+" FIG. 4.&mdash;POLE LANTERN (Scale 1/4)."></a></p>
+
+<p class="ctr">FIG. 4.&mdash;POLE LANTERN (Scale 1/4).</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/11e.png"><img src=
+"./images/11e_th.jpg" alt=" FIG. 5.&mdash;WINDLASS (Scale 1/10).">
+</a></p>
+
+<p class="ctr">FIG. 5.&mdash;WINDLASS (Scale 1/10).</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/11f.png"><img src=
+"./images/11f_th.jpg" alt=
+" FIG. 6.&mdash;LANTERN BOX (Scale 1/10)."></a></p>
+
+<p class="ctr">FIG. 6.&mdash;LANTERN BOX (Scale 1/10).</p>
+
+<p>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.</p>
+
+<p>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.&mdash;<i>Le G&eacute;nie
+Civil</i>.</p>
+
+<hr>
+<p>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.</p>
+
+<hr>
+<a name="20"></a>
+
+<h2>THE ELECTRIC DISCHARGE AND SPARK PHOTOGRAPHED DIRECTLY WITHOUT
+AN OBJECTIVE.</h2>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/11g.png"><img src=
+"./images/11g_th.jpg" alt=" FIG 1."></a></p>
+
+<p class="ctr">FIG 1.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/11h.png"><img src=
+"./images/11h_th.jpg" alt=" FIG 2."></a></p>
+
+<p class="ctr">FIG 2.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/12a.png"><img src=
+"./images/12a_th.jpg" alt=" FIG. 3."></a></p>
+
+<p class="ctr">FIG. 3.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/12b.png"><img src=
+"./images/12b_th.jpg" alt=" FIG. 4."></a></p>
+
+<p class="ctr">FIG. 4.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/12c.png"><img src=
+"./images/12c_th.jpg" alt=" FIG. 5."></a></p>
+
+<p class="ctr">FIG. 5.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/12d.png"><img src=
+"./images/12d_th.jpg" alt=" FIG. 6."></a></p>
+
+<p class="ctr">FIG. 6.</p>
+
+<p>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.&mdash;<i>G. Mareschal, in La Lumiere Electrique.</i></p>
+
+<hr>
+<a name="21"></a>
+
+<h2>THE TRUE CONSTANT OF GRAVITY.</h2>
+
+<p>Many of the readers of this journal may like to participate in
+the discussion of the following proposition. The statement is
+this:</p>
+
+<p>The space through which a body, near the surface of the earth,
+at mean latitude, <i>in vacuo</i>, 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.</p>
+
+<p>[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.]</p>
+
+<p>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 <i>decimal</i> 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, <i>geometrically,
+i.e.</i>, by strict decimalization upon the hour-angle. A
+mathematical reason underlies the proposition.</p>
+
+<pre>
+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
+
+</pre>
+
+<p>So that&mdash;</p>
+
+<pre>
+                                                      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
+</pre>
+
+<p>And so on, in strict <i>decimal</i> relation with the earth's
+semi-polar axis.</p>
+
+<p>A two-fold reason why the constant for latitude 45&deg; 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.</p>
+
+<p>JACOB M. CLARK.</p>
+
+<p>New York, February, 1885.</p>
+
+<hr>
+<a name="22"></a>
+
+<h2>ORIGIN OF THUNDERSTORMS.</h2>
+
+<p>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.</p>
+
+<hr>
+<a name="28"></a>
+
+<h2>IMPROVISED TOYS.</h2>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/13a.png"><img src=
+"./images/13a_th.jpg" alt=
+" FIG. 1.&mdash;Doll made of a Wild Poppy."></a></p>
+
+<p class="ctr">FIG. 1.&mdash;Doll made of a Wild Poppy.</p>
+
+<p>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?</p>
+
+<p class="ctr"><a href="./images/13b.png"><img src=
+"./images/13b_th.jpg" alt=
+" FIG. 2.&mdash;Hygrometric Doll; its Dress Colored with Chloride of Cobalt.">
+</a></p>
+
+<p class="ctr">FIG. 2.&mdash;Hygrometric Doll; its Dress Colored
+with Chloride of Cobalt.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/13c.png"><img src=
+"./images/13c_th.jpg" alt=
+" FIG. 3.&mdash;Old Man made of Lobster's Claws."></a></p>
+
+<p class="ctr">FIG. 3.&mdash;Old Man made of Lobster's Claws.</p>
+
+<p>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!</p>
+
+<p class="ctr"><a href="./images/13d.png"><img src=
+"./images/13d_th.jpg" alt=
+" FIG. 4.&mdash;Crocus Flowering in a Perforated Pot."></a></p>
+
+<p class="ctr">FIG. 4.&mdash;Crocus Flowering in a Perforated
+Pot.</p>
+
+<p>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!</p>
+
+<p class="ctr"><a href="./images/13e.png"><img src=
+"./images/13e_th.jpg" alt=
+" FIG. 5.&mdash;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.">
+</a></p>
+
+<p class="ctr">FIG. 5.&mdash;1. Paper Cross. 2. Method of Making
+the Cross. 3. Rabbits Made of Green Almonds. 4. Basket Made of
+Sedges. 5. Acorn Basket. 6. Fly-cage Made of aa Cork."&gt;</p>
+
+<p>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!</p>
+
+<p class="ctr"><a href="./images/13f.png"><img src=
+"./images/13f_th.jpg" alt=
+" FIG. 6.&mdash;The Lesson in Drawing.&mdash;An Illustrated Five-spot of Hearts.">
+</a></p>
+
+<p class="ctr">FIG. 6.&mdash;The Lesson in Drawing.&mdash;An
+Illustrated Five-spot of Hearts.</p>
+
+<p>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.</p>
+
+<hr>
+<a name="29"></a>
+
+<h2>THE &AElig;OLIAN HARP.</h2>
+
+<p>The &AElig;olian 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.</p>
+
+<p class="ctr"><a href="./images/13g.png"><img src=
+"./images/13g_th.jpg" alt=
+" FIG. 1.&mdash;KIRCHER'S &AElig;OLIAN HARP."></a></p>
+
+<p class="ctr">FIG. 1.&mdash;KIRCHER'S &AElig;OLIAN HARP.</p>
+
+<p>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 &AElig;olian 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.</p>
+
+<p>Without dwelling upon the history of the &AElig;olian harp, we
+may say that in modern times this instrument has been especially
+constructed in England, Scotland, Germany, and Alsace. The
+&AElig;olian harp of the Castle of Baden Baden, and those of the
+four turrets of Strassburg Cathedral are celebrated.</p>
+
+<p class="ctr"><a href="./images/13h.png"><img src=
+"./images/13h_th.jpg" alt=
+" FIG. 2.&mdash;FROST &amp; KASTNER'S IMPROVED &AElig;OLIAN HARP.">
+</a></p>
+
+<p class="ctr">FIG. 2.&mdash;FROST &amp; KASTNER'S IMPROVED
+&AElig;OLIAN HARP.</p>
+
+<p>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 &AElig;olian 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.</p>
+
+<p class="ctr"><a href="./images/14a.png"><img src=
+"./images/14a_th.jpg" alt=
+" FIG. 3.&mdash;&AElig;OLIAN HARP IN THE OLD CASTLE OF BADEN BADEN.">
+</a></p>
+
+<p class="ctr">FIG. 3.&mdash;&AElig;OLIAN HARP IN THE OLD CASTLE OF
+BADEN BADEN.</p>
+
+<p>The celebrated &AElig;olian 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 &AElig;olian 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 &AElig;olian harp has often inspired both writers of prose and
+poetry. Chateaubriand, in <i>Les Natchez</i>, 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.</p>
+
+<p class="ctr"><a href="./images/14b.png"><img src=
+"./images/14b_th.jpg" alt=
+" FIG. 4.&mdash;PLAN OF THE BADEN BADEN INSTRUMENT."></a></p>
+
+<p class="ctr">FIG. 4.&mdash;PLAN OF THE BADEN BADEN
+INSTRUMENT.</p>
+
+<p>Hector Berlioz, in his <i>Voyage Musicale en Italie</i>, has
+given as follows the curious effects that an &AElig;olian 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 &AElig;olian 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
+<i>abandon</i>, and a vague and infinite desire for another
+existence."</p>
+
+<p>An English physician, Dr. J.M. Cox, in his practical
+<i>Observations</i> 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 &AElig;olian harp.
+Other observers narrate that they have heard the efficacy of
+Aeolian sounds spoken of in Scotland for producing sleep.</p>
+
+<p>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.&mdash;<i>La Nature</i>.</p>
+
+<hr>
+<a name="23"></a>
+
+<h2>PHYSICS WITHOUT APPARATUS.</h2>
+
+<h3>MANUFACTURE OF ILLUMINATING GAS.</h3>
+
+<p class="ctr"><a href="./images/14c.png"><img src=
+"./images/14c_th.jpg" alt=
+" FIG. 1.&mdash;PRODUCTION OF ILLUMINATING GAS."></a></p>
+
+<p class="ctr">FIG. 1.&mdash;PRODUCTION OF ILLUMINATING GAS.</p>
+
+<p>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.</p>
+
+<h3>ELASTICITY OF BODIES.</h3>
+
+<p class="ctr"><a href="./images/14d.png"><img src=
+"./images/14d_th.jpg" alt=
+" FIG. 2.&mdash;EXPERIMENT ON THE ELASTICITY OF BODIES."></a></p>
+
+<p class="ctr">FIG. 2.&mdash;EXPERIMENT ON THE ELASTICITY OF
+BODIES.</p>
+
+<p>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.</p>
+
+<hr>
+<a name="24"></a>
+
+<h2>SCIENTIFIC AMUSEMENTS.</h2>
+
+<p><i>The Dance of the Electrified Puppets</i>.&mdash;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&mdash;the dance of the electrified
+puppets.</p>
+
+<p class="ctr"><a href="./images/14e.png"><img src=
+"./images/14e_th.jpg" alt=
+" FIG. 1.&mdash;DANCE OF THE ELECTRIFIED PUPPETS."></a></p>
+
+<p class="ctr">FIG. 1.&mdash;DANCE OF THE ELECTRIFIED PUPPETS.</p>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/14f.png"><img src=
+"./images/14f_th.jpg" alt=" FIG. 2.&mdash;SILHOUETTE PORTRAITS.">
+</a></p>
+
+<p class="ctr">FIG. 2.&mdash;SILHOUETTE PORTRAITS.</p>
+
+<p><i>Silhouette Portraits</i>.&mdash;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.&mdash;<i>La
+Nature</i>.</p>
+
+<hr>
+<a name="30"></a>
+
+<h2>HOW TO BREAK A CORD WITH THE HANDS.</h2>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/15a.png"><img src=
+"./images/15a_th.jpg" alt=
+" MODE OF BREAKING A CORD WITH THE HANDS."></a></p>
+
+<p class="ctr">MODE OF BREAKING A CORD WITH THE HANDS.</p>
+
+<p>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.</p>
+
+<p>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.</p>
+
+<hr>
+<a name="31"></a>
+
+<h2>AN AQUATIC VELOCIPEDE FOR DUCK HUNTING.</h2>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/15b.png"><img src=
+"./images/15b_th.jpg" alt=
+" FIG. 1.&mdash;AN AQUATIC VELOCIPEDE OF 1822."></a></p>
+
+<p class="ctr">FIG. 1.&mdash;AN AQUATIC VELOCIPEDE OF 1822.</p>
+
+<p>The amusing engraving of this velocipede, which is mentioned
+under the name of the <i>aquatic tripod</i>, 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&mdash;one in front, and the other behind. The
+propelling was done by alternately placing the feet on the
+ground.</p>
+
+<p class="ctr"><a href="./images/15c.png"><img src=
+"./images/15c_th.jpg" alt=
+" FIG. 2.&mdash;A TRIAL OF VELOCIPEDES IN 1818."></a></p>
+
+<p class="ctr">FIG. 2.&mdash;A TRIAL OF VELOCIPEDES IN 1818.</p>
+
+<hr>
+<a name="25"></a>
+
+<h2>A SUNSHINE RECORDER.</h2>
+
+<p>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.</p>
+
+<p class="ctr"><a href="./images/15d.png"><img src=
+"./images/15d_th.jpg" alt=" FIG. 1."></a></p>
+
+<p class="ctr">FIG. 1.</p>
+
+<p>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&deg; 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.</p>
+
+<p class="ctr"><a href="./images/15e.png"><img src=
+"./images/15e_th.jpg" alt=" FIG. 2."></a></p>
+
+<p class="ctr">FIG. 2.</p>
+
+<p>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.</p>
+
+<p>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.&mdash;<i>Herbert McLeod, Nature</i>.</p>
+
+<hr>
+<a name="32"></a>
+
+<h2>SKELETON OF A BEAR FOUND IN A CAVE IN STYRIA, AUSTRIA.</h2>
+
+<p>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.</p>
+
+<p>In one of these caverns near Peggau, in Styria, Austria, the
+skeleton of a bear (<i>Ursus Spelaeus</i>) and the skull of another
+bear of the same kind were found, both of which are shown in the
+annexed cut taken from the <i>Illustrirte Zeitung</i>, 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.</p>
+
+<p class="ctr"><a href="./images/16a.png"><img src=
+"./images/16a_th.jpg" alt=
+" SKELETON OF A BEAR FOUND IN A CAVE IN STYRIA, AUSTRIA."></a></p>
+
+<p class="ctr">SKELETON OF A BEAR FOUND IN A CAVE IN STYRIA,
+AUSTRIA.</p>
+
+<p>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.</p>
+
+<hr>
+<a name="5"></a>
+
+<h2>THE HARDNESS OF METALS.</h2>
+
+<p>The German <i>Verein zur Bedf&ouml;rderung des
+Gewerbefleisses</i> offers the following, among other prizes, for
+essays on technical subjects: One thousand marks <i>(&pound;50)</i>
+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 (&pound;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.</p>
+
+<hr>
+<p>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.</p>
+
+<hr>
+<a name="11"></a>
+
+<h2>STEAM YACHTS.</h2>
+
+<p>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 <i>Field</i>
+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 &amp; Co. Her best performance on the run was
+235 knots in 21&frac34; 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.</p>
+
+<hr>
+<p>A catalogue, containing brief notices of many important
+scientific papers heretofore published in the SUPPLEMENT, may be
+had gratis at this office.</p>
+
+<hr>
+<h2>THE SCIENTIFIC AMERICAN SUPPLEMENT.</h2>
+
+<h3>PUBLISHED WEEKLY.</h3>
+
+<h3>Terms of Subscription, $5 a Year.</h3>
+
+<p>Sent by mail, postage prepaid, to subscribers in any part of the
+United States or Canada. Six dollars a year, sent, prepaid, to any
+foreign country.</p>
+
+<p>All the back numbers of THE SUPPLEMENT, from the commencement,
+January 1, 1876, can be had. Price, 10 cents each.</p>
+
+<p>All the back volumes of THE SUPPLEMENT can likewise be supplied.
+Two volumes are issued yearly. Price of each volume, $2.50,
+stitched in paper, or $3.50, bound in stiff covers.</p>
+
+<p>COMBINED RATES&mdash;One copy of SCIENTIFIC AMERICAN and one
+copy of SCIENTIFIC AMERICAN SUPPLEMENT, one year, postpaid,
+$7.00.</p>
+
+<p>A liberal discount to booksellers, news agents, and
+canvassers.</p>
+
+<p><b>MUNN &amp; CO., Publishers,</b></p>
+
+<p><b>361 Broadway, New York, N.Y.</b></p>
+
+<hr>
+<h2>PATENTS.</h2>
+
+<p>In connection with the <b>Scientific American</b>, Messrs. MUNN
+&amp; 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.</p>
+
+<p>A special notice is made in the <b>Scientific American</b> 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 easily effected.</p>
+
+<p>Any person who has made a new discovery or invention can
+ascertain, free of charge, whether a patent can probably be
+obtained, by writing to MUNN &amp; Co.</p>
+
+<p>We also send free our Hand Book about the Patent Laws, Patents,
+Caveats. Trade Marks, their costs, and how procured. Address</p>
+
+<p><b>MUNN &amp; CO., 361 Broadway, New York.</b></p>
+
+<p>Branch Office, cor. F and 7th Sts., Washington, D.C.</p>
+
+<div>*** END OF THE PROJECT GUTENBERG EBOOK 14097 ***</div>
+</body>
+</html>
+
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author	Roger Frank <rfrank@pglaf.org>	2025-10-15 04:43:42 -0700
committer	Roger Frank <rfrank@pglaf.org>	2025-10-15 04:43:42 -0700
commit	5bc3ad02d881f073c48c5d23a83d554dec4dd798 (patch)
tree	7adbf9be55da28421c05435d0537ad2642b21f53 /14097-h