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| author | Roger Frank <rfrank@pglaf.org> | 2025-10-15 04:47:22 -0700 |
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| committer | Roger Frank <rfrank@pglaf.org> | 2025-10-15 04:47:22 -0700 |
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diff --git a/15708-h/15708-h.htm b/15708-h/15708-h.htm new file mode 100644 index 0000000..01d2d23 --- /dev/null +++ b/15708-h/15708-h.htm @@ -0,0 +1,5574 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<html> +<head> +<meta http-equiv="Content-Type" content= +"text/html; charset=ISO-8859-1"> +<title>The Project Gutenberg eBook of Scientific American +Supplement, March 21, 1891</title> +<style type="text/css"> +<!-- +body {margin-left: 15%; margin-right: 15%; background-color: white} +p {text-align: justify;} +img {border: 0;} +h1,h2,h3 {text-align: center;} +.note {margin-left: 2em; margin-right: 2em; margin-bottom: 1em;} +.ind {margin-left: 10%; margin-right: 10%;} +hr {text-align: center; width: 50%;} +.ctr {text-align: center;} +--> +</style> +</head> +<body> + + +<pre> + +The Project Gutenberg EBook of Scientific American Supplement, No. 794, +March 21, 1891, by Various + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Scientific American Supplement, No. 794, March 21, 1891 + +Author: Various + +Release Date: April 25, 2005 [EBook #15708] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN *** + + + + +Produced by Juliet Sutherland and the Online Distributed Proofreading +Team at www.pgdp.net. + + + + + + +</pre> + +<p style="margin-left: -10%; margin-right: -10%; text-align: center;"><a href="./images/title.png"><img src="./images/title_th.png" alt=""></a></p> +<h1>SCIENTIFIC AMERICAN SUPPLEMENT NO. 794</h1> +<h2>NEW YORK, March 21, 1891</h2> +<h4>Scientific American Supplement. Vol. XXXI., No. 794.</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="#ref1"> BOTANY.—New Race of Dwarf Dahlias.—A new and valuable + flowering plant, with portrait of the introducer.—1 illustration.</a></td></tr> + +<tr><td valign="top">II.</td><td><a href="#ref2"> CHEMISTRY.—Carbon in Organic Substances.—By J. MESSINGER.— + An improved method of determining carbon by inorganic + combustions.—1 illustration.</a></td></tr> + +<tr><td valign="top">III.</td><td><a href="#ref3"> CIVIL ENGINEERING.—A New Integrator.—By Prof. KARL + PEARSON. M.A.—An apparatus for use for the engineer in working + up areas, indicator diagrams, etc.—4 illustrations.</a></td></tr> + +<tr><td> </td><td><a href="#ref4">Best Diameter of Car Wheels.—The size of car wheels from the + standpoint of American engineering.—A plea for a moderate sized + wheel.</a></td></tr> + +<tr><td> </td><td><a href="#ref5">Improved Overhead Steam Traveling Crane.—A crane constructed + for use in steel works.—Great power and range.—3 illustrations.</a></td></tr> + +<tr><td> </td><td><a href="#ref6">Some Hints on Spiking Track.—A most practical article for telling + exactly how to conduct the operation on the ground.—1 illustration.</a></td></tr> + +<tr><td valign="top">IV.</td><td><a href="#ref7"> ELECTRICITY.—Electrical Laboratory for Amateurs.—By GEO. + M. HOPKINS.—A simple collection of apparatus for conducting a + complete series of electrical experiments.—17 illustrations.</a></td></tr> + +<tr><td> </td><td><a href="#ref8">The Action of the Silent Discharge on Chlorine.—How an electric + discharge affects chlorine gas.—An important negative result.</a></td></tr> + +<tr><td valign="top">V.</td><td><a href="#ref9"> ETHNOLOGY.—Some Winnebago Arts.—An interesting article + upon the arts of the Winnebago Indians.—A recent paper before + the New York Academy of Sciences.</a></td></tr> +<tr><td valign="top">VI.</td><td><a href="#ref10"> MEDICINE AND HYGIENE.—The Philosophy of Consumption. + —By Dr. J.S. CHRISTISON.—A review of the present theories of + consumption, and the role played in it by its bacillus.</a></td></tr> +<tr><td valign="top">VII.</td><td><a href="#ref11"> MUSIC.—Spacing the Frets on a Banjo Neck.—By Prof. C.W. + MACCORD.—A most practical treatment of this subject, with full + explanations.—1 illustration.</a></td></tr> +<tr><td valign="top">VIII.</td><td><a href="#ref12">ORDNANCE.—High Explosives in Warfare.—By Commander + F.M. BARBER, U.S.N.—An elaborate review of modern explosives + in their applicability to ordnance, etc.</a></td></tr> +<tr><td> </td><td><a href="#ref13">The Experiments at the Annapolis Proving Grounds.—The recent + tests at Annapolis described and illustrated.—Views of the + projectiles, plates, etc.—3 illustrations.</a></td></tr> + +<tr><td valign="top">IX.</td><td><a href="#ref14"> PHYSICS.—Arĉo-Picnometer.—An entirely novel form of hydrometer, + of very extended use and application.—1 illustration.</a></td></tr> +<tr><td valign="top">X.</td><td><a href="#ref15"> TECHNOLOGY.—Fabric for Upholstery Purposes.—Full technical + description of the method of producing a new and characteristic + fabric.—1 illustration.</a></td></tr> +<tr><td> </td><td><a href="#ref16">Gaseous Illuminants.—By Prof. VIVIAN B. LEWES.—Continuation + of this important article, treating of the water gas and special + processes, with analyses.</a></td></tr> +<tr><td> </td><td><a href="#ref17">Glove Making.—Early history of glove making in America.—Its + present aspects and processes.</a></td></tr> + +<tr><td> </td><td><a href="#ref18">Reversible Ingrain or Pro-Brussels Carpet.—An imitation of + Brussels carpet on the Ingrain principle.—Full description of the + process of making.—3 illustrations.</a></td></tr> + +<tr><td> </td><td><a href="#ref19">The Manufacture and Use of Plaster of Paris.—An excellent + treatment of a subject hitherto little written about.—Full particulars + of the manufacturing process. +</a></td></tr> +</table> + +<hr /> + +<h2><a name="ref5"></a><a name="Page_12679"></a>IMPROVED OVERHEAD STEAM TRAVELING +CRANE.</h2> + +<p>We show in Fig. 1 a general view, and in Figs. 2 and 3 a side +elevation and plan of an overhead steam traveling crane, which has +been constructed by Mr. Thomas Smith, of Rodley, near Leeds, for use +in a steel works, to lift, lower, and travel with loads up to 15 tons. +For our engravings and description we are indebted to <i>Industries.</i> +The crane is designed for hoisting and lowering while traveling +transversely or longitudinally, and all the movements are readily +controlled from the cage, which is placed at one end of and underneath +the transverse beams, and from which the load can be readily seen. All +the gear wheels are of steel and have double helical teeth; the shafts +are also of steel, and the principal bearings are adjustable and +bushed with hard gun metal. This crane has a separate pair of engines +for each motion, which are supplied with steam by the multitubular +boiler placed in the cage as shown. The hoisting motions consist of +double purchase gearing, with grooved drum, treble best iron chain +with block and hook, driven by one pair of 8 in. by 12 in. engines. +The transverse traveling motion consists of gearing, chain, and +carriage on four tram wheels, with grooved chain pulleys, driven by +the second pair of 6 in. by 10 in. engines, and the longitudinal +traveling motion driven by the other pair of 8 in. by 12 in. engines. +The transverse beams are wrought iron riveted box girders, firmly +secured to the end carriages, which are mounted on four double flanged +steel-tired wheels, set to suit a 38 foot span.</p> + +<p class="ctr"><a href="./images/1-crane.png"><img src="./images/1-crane_th.png" width="598" height="437" +alt="IMPROVED OVERHEAD TRAVELING CRANE"></a></p> +<p class="ctr">IMPROVED OVERHEAD TRAVELING CRANE.</p> + +<p class="ctr"><img src="./images/1-fig2.png" width="596" height="194" +alt="FIG. 2 SIDE ELEVATION"></p> +<p class="ctr">FIG. 2 SIDE ELEVATION.</p> + +<p class="ctr"><a href="./images/1-fig3.png"><img src="./images/1-fig3_th.png" width="579" height="245" +alt="FIG. 3 PLAN"></a></p> +<p class="ctr">FIG. 3 PLAN.</p> + +<hr /> + +<a name="ref4"></a><h2>BEST DIAMETER +CAR WHEELS.<a name="FN4anchor_1"></a><a href="#FN4_1"><sup>1</sup></a></h2> + +<p>It goes almost without saying that for any given service we want +the best car wheel, and in general it is evident that this is the one +best adapted to the efficient, safe and prompt movement of trains, to +the necessary limitations improved by details of construction, and +also the one most economical in maintenance and manufacture.</p> + +<p>It is our aim this afternoon to look into this question in so far +as the diameter of the wheel affects it, and in doing it we must +consider what liability there is to breakage or derangement of the +parts of the wheel, hot journals, bent axles, the effect of the weight +of the wheel itself, and the effect upon the track and riding of the +car, handling at wrecks and in the shop, the first cost of repairs, +the mileage, methods of manufacture, the service for which the wheel +is intended and the material of which it is made.</p> + +<p>Confining ourselves to freight and passenger service, and to cast +iron and steel wheels in the general acceptation of the term as being +the most interesting, we know that cast iron is not as strong as +wrought iron or steel, that the tendency of a rotating wheel to burst +is directly proportional to its diameter, and that the difficulty of +making a suitable and perfect casting increases with the diameter. +Cast iron, therefore, would receive no attention if it were not for +its far greater cheapness as compared to wrought iron or steel. This +fact makes its use either wholly or in part very desirable for freight +service, and even causes some roads in this country, + +notably the one with which I am connected, to find it profitable to +develop and perfect the cast iron wheel for use in all but special +cases.</p> + +<p>Steel, on the other hand, notwithstanding its great cost, is coming +more and more into favor, and has the great recommendations of +strength and safety. It is also of such a nature that wheels tired +with it run much further before being unfit for further service than +those made of cast iron, and consequently renewals are less frequent. +The inference would seem to be that a combination of steel and cast +iron would effect the desirable safeness with the greatest cheapness; +but up to the present this state of affairs has not yet been realized +to the proper extent, because of the labor and cost necessary to +accomplish this combination and the weakness involved in the manner of +joining the two kinds of material together.</p> + +<p>Taking up the consideration of the diameter of the wheel now, and +allowing that on the score of economy cast iron must be used for +wheels in freight service, we are led to reflect that here heavy loads +are carried, and there is a growing tendency to increase them by +letting the floor of the car down to a level with the draft timbers. +All this makes it desirable to have the + +wheels strong and small to avoid bent axles and broken flanges, to +enable us to build a strong truck, to reduce the dead weight of cars +to a minimum, and have wrecks quickly cleared away. The time has not +yet come when we have to consider seriously hot journals arising from +high speed on freight trains, and a reasonable degree only of easy +riding is required. The effect on the track is, however, a matter of +moment. Judging from the above, I should say that no wheel larger than +one 33 in. in diameter should be used under freight cars. Since +experience in passenger service shows that larger cast iron wheels do +not make greater mileage and cost more per 1,000 miles run, and that +cast iron wheels smaller than 33 in., while sometimes costing less per +1,000 miles run, are more troublesome in the end, it is apparent that +33 in. is the best diameter for the wheels we have to use in freight +service.</p> + +<p>When we take up passenger service we come to a much more difficult +and interesting part of the subject, for here we must consider it in +all its bearings, and meet the complications that varying conditions +of place and service impose. In consequence, I do not believe we can +recommend one diameter for all passenger car wheels although such a +state of simplicity would be most desirable. For instance, in a sandy +country where competition is active, and consequently speed is high +and maintained for a length of time without interruption, I would +scarcely hesitate to recommend the use of cast iron for car wheels, +because steel will wear out so rapidly in such a place that its use +will be unsatisfactory. If then cast iron is used, we will find that +we cannot make with it as large a wheel as we may determine is +desirable when steel is used. And just to follow this line out to its +close I will state here that we find that 36 in. seems to be the +maximum satisfactory diameter for cast iron wheels, because this size +does not give greater mileage than 33 in., costs more per 1,000 miles +run, and seems to be nearer the limit for good foundry results. On the +other hand, a 36 in. wheel rides well and gives immunity from hot +boxes—a most fruitful source of annoyance in sandy districts. It is +also easily applicable where all modern appliances under the car are +found, including good brake rigging. In all passenger service, then, I +would recommend 36 in. as the best diameter for cast iron wheels.</p> + +<p>Next taking up steel wheels, a great deal might be said about the +different makes and patterns, but as the diameter of wheels of this +kind is not limited practically to any extent by the methods of +manufacture, except as to the fastening of the wheel and tire +together, we will note this point only. Tires might be so deeply cut +into for the introduction of a retaining ring that a small wheel would +be unduly weakened after a few turnings.</p> + +<p>On the other hand, when centers and tires are held together by +springing the former into the latter under pressure, it is possible +that a tire of larger diameter might be overstrained. But allowing +that the method of manufacture does not limit the diameter of a steel +wheel as it does a cast iron one, the claim that the larger diameter +is the best is open to debate at least, and, I believe, is proved to +the contrary on several accounts. It is argued that increasing the +diameter of a wheel increases its total mileage in proportion, or even +more. Whether this be so or not, there are two other +<a name="Page_12680" id="Page_12680"></a>very objectionable features that come with an increase in +diameter—the wheel becomes more costly and weighs more, without +giving in all cases a proportionate return. We have to do more work in +starting and stopping, and in lifting the large wheel over the hills, +and when the diameter exceeds a certain figure we have to pay more per +1,000 miles run. I am very firmly convinced that the matter of dead +weight should receive more attention than it does, with a view to +reducing it. The weight of six pairs of 42 in. wheels and axles alone +is 15,000 to 16,000 lb.</p> + +<p>The matter of brakes is coming up for more attention in these days +of high speed, heavy cars and crowded roads, and the total available +braking power, which has hitherto been but partially taken advantage +of, must be fully utilized. I refer to the fact that many of our +wheels in six-wheel trucks have gone unbraked where they should not. +As the height of cars and length of trucks cannot well be increased +for obvious reasons, it is necessary to keep the size of the wheels +within the limits that will enable us to get efficient brakes on all +of them that carry any weight. This is not easy with a 42 in. wheel in +a six-wheel truck, which is usually the kind that requires most +adjustment and repairs after long runs. The Pullman Co. has recognized +this fact, and is now replacing its 42 in. wheel with one 38 in. in +diameter.</p> + +<p>A 42 in. wheel with 4 in. journal has a greater leverage wherewith +to overcome the resistance of journal friction than the 38 in. wheel +with the same journal, and even more than the 36 in. and 33 in. wheels +with 33/4 in. and 31/2 in. journals respectively, but the fact remains +that the same amount of work has to be done in overcoming the friction +in each case, and what may be gained in ease of starting with the +large wheel is lost in time necessary to do it, and in the extra +weight put into motion.</p> + +<p>A large wheel increases the liability to bent axles in curving on +account of greater leverage unless the size and weight of the axle are +increased to correspond, and the wheel itself must be made stronger. A +four or six wheel truck will not retain its squareness and dependent +good riding qualities so well with 42 in. wheels as with 33 in. ones. +Besides the brakes, the pipes for air and steam under the cars +interfere with large wheels, and as a consequence of all this 42 in. +wheels have been replaced by 36 in. ones to some extent in some places +with satisfactory results. On one road in particular so strong is the +inclination away from large wheels that 30 in. is advocated as the +proper size for passenger cars.</p> + +<p>On the other hand, there is no doubt a car wheel may be too small, +for the tires of small wheels probably do not get as much working up +under the rolls, and therefore are not as tough or homogeneous. Small +wheels are more destructive to frogs and rail joints. They revolve +faster at a given speed, and when below a certain size increase the +liability to hot journals if carrying the weight they can bear without +detriment to the rest of the wheel. Speed alone I am not willing to +admit is the most prolific source of hot boxes. The weight per square +inch upon the bearing is a very important factor. I have found by +careful examination of a great many cars that the number of hot boxes +bears a close relation to the weight per square inch on the journal +and the character of lubrication, and is not so much affected by the +size of wheel or speed. These observations were made upon 42 in., 36 +in. and 33 in. wheels in the same trains. We find, furthermore, that +while a 3-3/8 in. journal on a 33 in. wheel is apt to heat under our +passenger coaches, a 33/4 in., even when worn 3-5/8 in., journal on a 36 +in. wheel runs uniformly cool. In 1890 on one division there were +about 180 hot boxes with the small wheel, against 29 with the larger +one, with a preponderance of the latter size in service and cars of +the same weight over them.</p> + +<p>I do not know that there is any more tendency for a large wheel to +slide than a small one under the action of the brakes, but large +wheels wear out more brake shoes than small ones, if there is any +difference in this particular.</p> + +<p>My conclusions are that 42 in. is too large a diameter for steel +wheels in ordinary passenger service, and that 36 in. is right. But as +steel-tired wheels usually become 3 in. smaller in diameter before +wearing out, the wheel should be about 38 in. in diameter when new. +Such a wheel can be easily put under all passenger cars and will not +have become too small when worn out. A great many roads are using 36 +in. wheels, but when their tires have lost 3 in. diameter they have +become 33 in. wheels, which I think too small.</p> + +<p>There are many things I have left unsaid, and I am aware that some +of the members of the club have had most satisfactory service with 42 +in. wheels so far as exemption from all trouble is concerned, and +others have never seen any reason for departing from the most used +size of 33 in.</p> + +<p>One more word about lightness. A wrought iron or cast steel center, +8 or 9 light spokes on a light rim inside a steel tire, makes the +lightest wheel, and one that ought to be in this country, as it is +elsewhere, the cheapest not made of cast iron.</p> + + +<a name="FN4_1"></a><a href="#FN4anchor_1">[1]</a><div class="note">By Samuel Porcher, assistant engineer motive power department, +Pennsylvania Railroad. Read at a regular meeting of the New York +Railroad Club, Feb. 19, 1891.</div> + +<hr /> + +<a name="ref3"></a><h2>A NEW INTEGRATOR.<a name="FN3anchor_1"></a><a href="#FN3_1"><sup>1</sup></a></h2> +<h3>By Professor KARL PEARSON, M.A.</h3> + +<p>As I fear the title of my paper to our Society to-night +contains two misstatements of fact in its three +words, I must commence by correcting it. In the first +place, the instrument to which I propose to draw your +attention to-night is, in the narrow sense of the words, +neither an integrator nor new. The name "integrator" +has been especially applied to a class of instruments +which measure off on a scale attached to them the +magnitude of an area, arc, or other quantity. Such +instruments do not, as a rule, represent their results +graphically, and we may take, as characteristic examples +of them, Amsler's planimeter and some of the +sphere integrating machines.</p> + +<p>An integrator which draws an absolute picture of the +sum or integral is better termed an "integraph." The +distinction is an important and valuable one, for while +the integraph theoretically can do all the work of the +integrator, the latter gives us in niggardly fashion one +narrow answer, <i>et prĉterea nil</i>. The superiority of the +integraph over the integrator cannot be better pointed +out than by a concrete example. The integrator could + +determine by one process, the bending moment, from +the shear curve, at any one chosen point of a beam; +the integraph would, by an equally simple single process, +gives us the bending moment at all points of the +beam.</p> + +<p>In the language of the mathematician, the integrator +gives only that miserly result, a definite integral, +but the integraph yields an indefinite integral, a picture +of the result at all times or all points—a much +greater boon in most mechanical and physical investigations. +Members of our Society as students of University +College have probably become acquainted +with a process termed "drawing the sum curve from +the primitive curve." Many have probably found this +process somewhat wearisome; but this is not an unmixed +evil, as the irksomeness of any manual process +has more than once led to the invention of a valuable +machine by the would-be idler. Thus our innate desire +to take things easy is a real incentive to progress. +It was some such desire as this on my part which led +me, three years ago, to inquire whether a practical instrument +had not been, or could not be, constructed +to draw sum curves. Such an instrument is an integraph, +and the one I have to describe to you to-night +is the outcome of that inquiry. It is something better +than my title, for it is an integraph, and not an integrator.</p> + +<p class="ctr"><a href="./images/3-int.png"><img src="./images/3-int_th.png" width="592" height="402" +alt="A NEW INTEGRATOR"></a></p> +<p class="ctr">A NEW INTEGRATOR.</p> + +<p>Before I turn to its claims to be considered new, I +must first remind you of the importance of an instrument +of this kind to the draughtsman. I put aside its +purely mechanical applications, where it has been, or +can be, attached to the indicators of steam engines, to +dynamometers, dynamos, and a variety of other instruments +where mechanical integration is of value. +These lie entirely outside my field, and I propose +only to refer to a few of the possible services of the +integrator when used by hand, and not attached to a +machine.</p> + +<p>The simple finding of areas we may omit, as the +planimeter will do that equally well. But of purely +graphical processes which the integraph will undertake +for us, I may mention the discovery of centroids, +of moments of inertia (or second moments), of a scale +of logarithms, of the real roots of cubic equations, and +of equations of higher order (with, however, increasing +labor). Further, the calculation of the cost of cutting +and embanking for railways by the method of Bruckner +& Culmann, the solution of a very considerable +number of rather complex differential equations, various +problems in the storage of water, and a great +variety of statistical questions may all be completely +dealt with, or very much simplified by aid of the integraph.</p> + +<p>In graphical statics proper the integraph draws +successively the curves of shear, bending moment +slope, and deflection for simple beams; it does the like +service for continuous beams, after certain analytical +or graphical calculations have first been made; it can +further lighten greatly the graphical work in the treatment +of masonry arches and of metal ribs. In graphical +hydrostatics it finds centers of pressure and gives a +complete solution for the shear and bending moment, +curves in ships, besides curves for their stability. In +graphical dynamics the applications of the integraph +seem still more numerous. It enables us to pass from +curves of acceleration to curves of speed, and from +curves of speed to curves of position. Applied to the +curve of energy of either a particle or the index point +of a rigid body, it enables us by the aid of easy auxiliary +processes to ascertain speeds and curves of action. +In a slightly altered form, that of "inverse summation," +we can pass from curves of action to curves of +position, and deal with a great range of resisted motions, +the analysis of which still puzzles the pure +mathematician; the variations of motion in flywheels, +connecting rods, and innumerable other parts of mechanism, +may all be calculated with much greater ease +by the aid of an integraph. Shortly, it is the fundamental +instrument of graphic dynamics.</p> + +<p>It would be needless to further multiply the instances +of its application; the questions we have rather to ask +are: Can a practical instrument be made which will +serve all these purposes? Has such an instrument +been already put upon the market? If I have to answer +these questions in the negative, it is rather a +doubtful negative, for the instrument I have to show +you to-night goes so far, and suggests so many modifications +and possibilities, which would take it so much +further, that it is very close to bringing the practical +solution to the problem.</p> + +<p>Let me here lay down the conditions which seem +essential to a practical integraph. These are, I think, +the following:</p> + +<p>1. The price must be such that it is within the reach +of the ordinary draughtsman's pocket. The Amsler's +planimeter at £2 10s. or £3 may be said to satisfy this +first condition. The price for the first complex integraph +designed by Coradi was £24 to £30. The modified +form in which I show it to-night is estimated to +cost retail £14. Till an equally efficient instrument +can be produced for £5 I shall not consider the price +practical. If the error of its reading be not sensibly +greater than that of a planimeter, it is certainly worth +double the money.</p> + +<p>2. The instrument must not be liable to get out of +order by fair handling and a reasonable amount of +wear and tear. I cannot speak at present with certainty +as to how far our integraph satisfies this condition; +it is rather too complex to quite win my confidence +in this respect.</p> + +<p>3. It must be capable of being used on the ordinary +drawing board, and of having a fairly wide range on it, +<i>i.e.</i>, it must not be limited to working where the primitive +is at one part only of the board.</p> + +<p>This condition takes out of every day practical +drawing use the integraph invented by Professors +James and Sir William Thomson, in which the sum +curve is drawn on a revolving cylinder. It is essential +that the sum curve should be drawn on the board not +far from the primitive, and that this sum curve can be +summed once or twice again without difficulty. The +time involved in drawing the four sum curves, for example, +required in passing from the load curve to the +deflection curve of a simple beam, if these curves were +drawn on different pieces of paper and had to be shifted +on and off cylinders, would probably be as long as +the ordinary graphical processes. Coradi's integraph +works on an ordinary drawing board, but since there +are nearly 10 inches between the guide point and tracer, +the sum curve is thrown 10 inches behind the + +primitive in each integration. Thus a double summation +requires say 26 inches of board, and it is impossible +to integrate thrice without reproducing the primitive. +The fact that the primitive and sum curve are +not plotted off on the same base is also troublesome +for comparison, and involves scaling of a new base for +each summation. I have endeavored to obviate this +by always drawing the second sum curve on a thin +piece of paper pinned to the board, which can then be +moved back to the position of the first primitive. But +this shifting, of course, involves additional labor, and +is also a source of error.</p> + +<p>I should like to see the trace and guide chariots on +the same line of rails, one below the other, were this +possible without producing the bad effect of a skew, +pull or push.</p> + +<p>4. The practical integraph must not have a greater +maximum error than 2 per cent. The mathematical +calculations, which are correct to five or six places of +decimals, are only a source of danger to the practical +calculator of stresses and strains. They tend to disguise +the important fact that he cannot possibly know +the properties of the material within 2 per cent. error, +and therefore there is not only a waste of time, but a +false feeling of accuracy engendered by human and +mechanical calculation which is over-refined for technical +purposes.</p> + +<p>For comparative purposes I have measured the areas +of circles of 1 inch, 2 inches, and 3 inches radius, the +guide being taken round the circumference by means +of a "control lineal," first with an ordinary Amsler's +planimeter and then with the integraph. I have obtained +the following results:</p> + +<table summary="Calc area" cellpadding=0 border=1 align="center"> +<colgroup span="7"><col align="center"><col span="6" align="right"></colgroup> +<tr><th colspan=3> </th><th ALIGN="center" colspan="4">By integraph.</th></tr> +<tr><th>Radius of circle.<br />in.</th><th>Calculated areas.</th><th>By Planimeter.</th> +<th>Middle.<br /> p=2 in.</th><th>Upper end.<br /> p=2 in.</th><th>Middle.<br /> p=4 in.</th><th>Upper end. <br />p=4 in.</th></tr> +<tr><td> 1 </td><td> 3.14159 </td><td> 3.140 </td><td> 3.140</td><td> 3.138</td><td> 3.120</td><td> 3.120</td></tr> +<tr><td> 2 </td><td> 12.56636 </td><td> 12.55 </td><td>12.36*</td><td>12.546</td><td>12.568</td><td>12.552</td></tr> +<tr><td> 3 </td><td> 28.27431 </td><td> 28.24 </td><td>..</td><td>..</td><td>28.280</td><td>28.288</td></tr> +</table> + +<p class="ctr">* Cross bar had to be moved during tracing.</p> + + +<p>From this it follows that the error of the planimeter +is less than 0.1 per cent. and that of the integraph +about 0.5 per cent. Obviously we could make this +error much less if we excluded small areas measured +with large polar distances, or such polar distances that +the cross bar must be shifted. Excluding such cases, +we see that the accuracy of the integraph scarcely falls +behind that of the planimeter and is quite efficient for +practical purposes. It must be borne in mind that the +above measurements were made with the "control +lineal," an arrangement which carries the guide round +a circle of the exact test area. In most cases the +curve has to be followed by hand, and the error will be +greater—greater probably for the integraph than for +the planimeter, as the former is distinctly hard to guide +well.</p> + +<p>I think, then, we should be safe in saying that the +error of the integraph is not likely to be greater and is +probably less than 2 per cent., so that in this respect +the instrument may be considered a practical one.</p> + +<p>5. A further condition for a good integraph is that +it should have a wide range of polar distances, and +that it should be easily set at those distances.</p> + +<p>One of the conditions I gave to the maker of the instrument +was that it should be able to take all polar +distances from one to ten half-inches. This condition +he can scarcely be said to have fulfilled. With polar +distances of 1/2 inch and 1 inch, the machine works unsatisfactorily, +which indeed might have been foreseen +from the construction of its sliding bars. It works +best from 2.5 inches to 5 inches, and this is the range +to which I think we ought to confine the present type +of instrument. As the last conditions I may note that:</p> + +<p>6. A practical integraph ought to be easy to read.</p> + +<p>7. Draw a good clear curve.</p> + +<p>The scale on the present instrument is very inconvenient, +as it is often almost out of sight; the curve it +draws, on the other hand, I consider very satisfactory, +when the pencil is loaded, say, with a planimeter +weight. On the whole, I think you will agree with +me that this integraph goes a good way, if not the +whole way, toward fulfilling the conditions of a practical +instrument.</p> + +<p>I next turn to its construction and the claim it has +to be considered in any way new. Let me briefly remind +our members of the process by which an element +Q R of the sum curve (Fig. 1) corresponding to the +point P on the primitive is drawn; P M being the mid-ordinate +of L N, a horizontal element, P B is drawn +perpendicular to any vertical line A B; and O A being +a constant distance termed the base or "polar distance," +Q R is drawn between the ordinates of L and +W, parallel to O B. If P' be the point where P M meets +Q R, we note the following relationship of P' to P.</p> + +<p>1. If P moves along a horizontal line, O B remains +unchanged, and, therefore, Q R or P' must move in the +straight line Q R parallel to O B.</p> + +<p>2. If P moves along a vertical line, P' does not +change, but Q R turns round it, remaining parallel to +O B.</p> + +<p class="ctr"><a href="./images/3-figs.png"><img src="./images/3-figs_th.png" width="599" height="366" +alt="FIG. 1, 2, 3."></a></p> +<p class="ctr">FIG. 1, 2, 3.</p> + +<p>Without taking the trouble, as I ought to have done, to inquire +what previous investigations had achieved in this matter, I thought, +three years ago, I could get an apparatus to save me the trouble of +drawing sum curves, made somewhat after the following fashion.</p> + +<p>P (Fig. 2) is the guide or point to be taken round the primitive. +It is attached to a block, D, which works along the bar, B C, which in +its turn moves on the four wheels, e e f f, upon the frame R S U T +fixed upon the drawing board. O A is fixed perpendicular to R U, and +is such that O may be fixed at various points to determine the polar +distance. O B D is a light bar passing freely through B and forming +one side of a parallel ruler of two or more points, g g, h h, i i. +Along i i is a slot and in this works a loaded block containing a +wheel P', whose plane is always parallel to i i. This block also +passes through a slot in D E, an arm at right angles to B C. A little +consideration will show that P', if worked at all, would trace out the +sum curve of P.</p> + +<p>It was only when I showed the rough idea of this to +<a name="Page_12681" id="Page_12681"></a>Professor Kennedy, with the view of ascertaining what would be the +amount of back-lash and friction, that I learned that Mr. Boys had +already invented a very similar integrator. In his model the double +parallel ruler is replaced by two endless strings and pulleys, and the +bar, B C, by a T square.</p> + +<p>Although this integrator was afterward made in a less crude form, I +do not think it has ever been a practical instrument for the +draughtsman. Shortly afterward I came across a work by +Abdank-Abakanowicz, entitled "Les Integraphes," being a study of a +"new kind of mechanical integrator."</p> + +<p>The new kind of integrator was really only an independent version +of Boys' instrument, but in many respects a great improvement. The +real merit will ultimately belong to the scientific instrument maker +who constructs an instrument reasonably cheap and capable of efficient +practical service. Abdank-Abakanowicz's integrator however certainly +went further in the practical direction than any previously +constructed. The drawing board machines, it is true, of rather a +complex nature, were actually exhibited to the Paris Academy, but no +more have been made. The instrument before me was made by Coradi, of +Zurich, on conditions laid down by me, namely, that the cost should +not exceed £14, and that polar distances should range between one and +ten half-inches. The first machine made by Coradi on these lines was, +by a misunderstanding, sold in Germany, but the one I exhibit is the +first, I believe, that has reached England, and to this extent I may, +perhaps, be permitted to call it new. I look upon it rather as a +suggestion upon which a still more practical instrument can be made in +this country than as a perfect model. I believe there would be a wide +sale for such an instrument were it once generally known to exist, +and, what is more to work efficiently. It remains for me to point out +in what the Abdank-Abakanowicz, or, rather, Coradi, integraph differs +from Boys' instrument.</p> + +<p>Two points deserve special attention. In the first place, the fixed +frame is abolished, and the horizontal motion of P (Fig. 3), the guide +point, is produced by putting the whole frame on friction rollers; in +the second place, as a necessary result of the first change, the guide +point carries about with it its own polar system, which renders the +changes in length of "rays" much more manageable. f f, f' f' is a +frame moving on four roughed wheels, e e e e, so that it can only move +in the direction, f', which we may term horizontal. f f and f' f' are +rails guiding the chariots, A and B, from f to f and from f' to f'. Of +these chariots, A contains the guide point, P, to trace out the +primitive with, and B the pencil, P', to draw the sum curve, <i>i.e.</i>, +the tracer. The chariot, B, like Boys' tracer, is heavily loaded. g g +is a horizontal bar rigidly attached to the crossbars, q q and q' q', +of the frame. On g g is a movable pivot, to which h, which determines +the pole, k<sub>0</sub> h being the polar distance. k<sub>0</sub> is +the position of a second point, k, on the chariot, A, when the guide +point, P, is on the initial line, g g. l l is a bar with a long slot +in it, in which work the pivots, h and k; this bar represents the +"ray." A projecting arm k k' has been introduced to enable me to +shorten the polar distance down to 2 in. and under by removing the +pivot, k to k'. m m is a bar attached to the block, n, which runs on l +l, so that m m is always perpendicular to l l. On the chariot, B, is +another bar, m' m', capable of turning round the pivot, d, and always +maintained parallel to + +m m by the rods, m m', m m'. Attached to m' m' is a wheel, w, whose +axis is parallel to m' m'. This wheel, therefore, always moves +perpendicular to m' m', and therefore to m m; hence it moves parallel +to the ray, h k. A pencil, P', attached traces out the sum curve. If +we wish to use the machine as an integrator, we have merely to measure +the vertical distance traversed by P', or the distance B has run along +f' f'. This is done by means of a scale on f f'. If k be brought down +to k<sub>0</sub>, w runs parallel to g g, or P' traces out a +horizontal straight line, which is thus the base line. If k be fixed +as near as possible to k<sub>0</sub>, which is done by means of a +screw in f f at k<sub>0</sub>, the chariot, B, can be run down f' f' +as nearly opposite to k<sub>0</sub> as can be guessed at; a horizontal +line may then be drawn as base line, and the guide point, P, brought +into this line by a clamping screw with which it is provided. The +instrument is then ready for action. There is a brake on one of the +roughed wheels to check or stop the motion of the integraph when +required.</p> + +<p>The instrument works best when the chariots, A and B, are about +opposite to each other; when they are at opposite extremities of f f +and f' f' respectively, the pull at P tends to produce a skewing +couple. If the chariot, B, could be put upon f f and work, if needful, +by a double parallelogram from m m, we should have, excepting the skew +pull, some great practical advantages. We might throw the whole of the +weight of the machine on the one pair of friction wheels, and replace +the other pair by a single wheel, the portion q' f' f' q' of the +machine virtually disappearing. Three wheels, of course, would be a +real improvement. Further, we should have the sum curve and primitive +drawn to the same base line, and the simplification in the number of +parts ought largely to reduce the cost of the instrument.</p> + +<p>To be able to perform "inverse summation" (which in the language of +differential calculus is to find y as a function of x, when we are +given y=f(dy/dx), and not dy/dx=f(x) as usual), we only want a means +of making the plane of the wheel, w, parallel instead of perpendicular +to m' m', and it is easy to design a modification in the construction +which will allow of this change.</p> + +<p>I hope the above description of the integraph may have made its +construction and method of working sufficiently clear. Those of you +who have a taste for mechanical work, and the necessary tools, might, +I think, with some patience, construct a workable integraph. I expect +the pivots would be the hardest part of the work. I hope, some day, +myself to have another instrument made with a more readily changeable +polar distance, with trace and guide points working in the same +vertical, and a wheel permitting of inverse summation. If this project +is ever carried out, I hope I may be permitted to communicate further +particulars to our society.</p> + +<a name="FN3_1"></a><a href="#FN3anchor_1">[1]</a><div class="note">A paper read before the University College Engineering Society on January 22.—<i>Engineering</i>.</div> + +<hr /> + +<p>After some forty years of immersion in the +waters of the pool of Echoschacht, not far from +Hermannstadt, several human bodies have been +brought to the surface in a state of perfect preservation. </p> + +<hr /> + + +<a name="ref6"></a><h2>SOME HINTS ON SPIKING TRACK.</h2> + + +<p>The usual dimensions of track spikes are 51/2 X 9.16 +inches square, their weight about half a pound each. +Their common defects are brittleness and imperfect +points. In spiking track, the most important points +to be attended to are the proper spacing of the ties +and driving the spikes in such a manner that the ties +shall be held in place at right angles to the track and +the rails in true gauge; to insure the latter, the track +gauge should always be used when spiking the gauge +side, the rail being held to proper position by a lining +bar. The gauge should be kept about 6 or 8 in. ahead +of the tie being spiked and should not be lifted until +the spikes are driven home; gauges should be tested +regularly and every morning when they are to be used +all day, so as to insure a true gauge all the time. The +two inner spikes should be set on one side of the tie +and the two outer spikes on the other, as indicated in +the accompanying sketch. This prevents the tie from +slewing around, and thus deranging the gauge of the +track, as well as interfering with the proper spacing +of the ties. The joints and centers should be spiked +first, which will bring the rails to their proper position +on the ties, which in turn will assist intermediate spiking. +Each tie should be carefully gauged as spiked and, +as before indicated, the ties with the broadest faces +being selected for the joints.</p> + +<p>In gauging ties it is very convenient to have measured +off on the handles of the mauls in the hands of the +forward spikers the distance from the outside of the +rail to the end of the tie. This distance will then be +gauged on the tie, when it will be lifted to the rail and +securely spiked; the gauge is then used, and the loose +rail held in place with the lining bar as previously indicated, +loose gauge being given on curves, in accordance +with directions of the engineer, the allowance for +which is about 1/8 in. on a 2° curve, up to about 3/4 in. +on a 12° curve.</p> + +<p>This widening of the gauge should begin on the tangent, +back of the P.C., the full amount of excess over +true gauge being reached by the time the P.C. is +reached and continue all the way around the curve, +running from the P.T. in the same manner as back of +the P.C.</p> + +<p>The spikes should always be driven home straight +and at right angles with the face of the ties. When +the foreman in charge of the track-laying work sees a +spiker, when the spike is nearly home, strike the spike +head laterally, which is done to make it lie snugly to +the rail, he should at once check such imperfect work +and put the man who does it at other work. The foreman +in charge of gang of spikers should be experienced +in this branch of the work, and by weeding out imperfect +workers, can soon get together a first-rate gang of +spikers. But no trouble will be experienced from carelessly +driven spikes, if the tie has the spike holes bored +into it, before laying. This is considered good practice, +but rather expensive.</p> + +<p class="ctr"><img src="./images/3-rail.png" width="400" height="370" +alt="Rail Illustration"></p> + +<p>For boring the holes quickly and accurately, a proper +template should be made, by which the ties are marked +for the borers, who should be provided with boring +machines, by the use of which a hole, square with the +face of the tie is bored. The boring machines should +be so arranged as not to cut the hole beyond the required +depth, which should be slightly less than the +length of the spike. The diameter of the holes should +be about 1-16 of an inch less than the thickness of the +spike. This not only does away with the spike tearing +its way through the timber and thus injuring its fiber +to a great extent and causing it to be much more susceptible +to rot, but it is said to increase the adhesion of +the spike in hard wood ties at least 50 per cent. But +in order that the best results may be obtained, the +spike should be flattened on either side of the sloping +point, which will generally prevent it leaving the +hole.</p> + +<p>The spikers should carefully avoid striking the rail +with their mauls, as such carelessness often produces +fracture, which sometimes causes the rail to break in +two at such points, which is liable to produce derailment +and serious accident. Spike mauls should weigh +not less than nine nor more than ten pounds, and +should be on straight handles, not less than 3 ft. long. +After considerable use, the face of the maul will become +somewhat rounded, and when this takes place it +should be sent to the shop to be redressed. The last +blow on the spike should be only sufficiently hard to +cause its throat to fit snugly on the rail; a harder blow +will often fracture the spike in such a manner as to +cause the head in a short time to break off and leave +the rail unsupported at that point. Foremen should +not allow a spike to be pulled, especially in frosty +weather, until it has been first struck a light blow to +break the rust and loosen its hold in the wood. The +filling of old spike holes with wooden plugs is bad +practice, for the reason that they will cause the spike +in a short time to slip from its place; to fill the holes +with sand is much better, and spikes driven in holes so +filled will hold much more firmly. The best form of +spike I have seen is the curved safety railroad spike; +this spike takes in the tie a position which enables it +to resist the thrust of the rail against it much more +effectually than the ordinary spike can possibly do. I +<a name="Page_12682" id="Page_12682"></a>have seen in good condition, one of these curved spikes +which was said to have been driven eight times. The +cost of the curved safety spike is more than that of the +ordinary spike, but it is better made, holds the track +better, and, I believe, is worth more than the difference +asked for it.—<i>J.A. Hall, on Construction and Maintenance +of Track, before American Society of Civil +Engineers.</i></p> + +<hr /> + +<a name="ref13"></a><h2>THE EXPERIMENTS AT THE ANNAPOLIS +PROVING GROUNDS.</h2> + +<p>The desperate war that has been waging between +the gun and armor plate, ever since the period when +protective plates were first applied to naval constructions, +is familiar to all. In this conflict the advantage +seems to lean toward the side of the gun, the power of +penetration of which can be increased to almost indefinite +limits, at least theoretically, while we quickly +reach the extreme thicknesses of metal that can be +practically employed for the protection of ships.</p> + +<p>So, in recent times, researches have been making +upon the efficacy of armor plating, no longer in its exaggeration +of thickness, but in the intrinsic quality of +the metal of which it is composed. Metallurgists have +applied themselves to the work and have thus brought +out various products, among which the plates called +"compound," of Messrs. Cammell & Co., have obtained +a great notoriety. These plates, formed of a true plating +of steel upon a bed of soft iron, have been much +in vogue in the English navy, and seemed as if they +were to be adopted about everywhere.</p> + +<p>The Creusot works alone, of all competitors, were +able to fight against the general infatuation. Many +comparative experiments had already demonstrated +the superiority of the Creusot "all steel" plates over +the Cammell plates, but Messrs. Schneider & Go. were +not willing to stop here, and finally produced the new +nickel steel plate, which is by far superior to their steel +plates.</p> + +<p>Some comparative trials of these various armor +plates have recently been made by a military commission +of the United States at the Annapolis proving +grounds. Three plates, one a Cammell, the second a +steel, and the third a nickel steel (the two last from +Creusot), were here submitted to firing, under absolutely +identical conditions.</p> + +<p>Our engravings show the proving grounds and the +details of the arrangements adopted for backing the +plates.</p> + +<p>Of the three plates, the Cammell was the thickest +(11 in.) The steel one was 103/4 in. in thickness, and +the nickel steel 101/2 in. The last, therefore, was at a +disadvantage with respect to the two others.</p> + +<p>The plates were arranged tangentially to an arc of a +circle whose center was occupied by the pivot of the +gun, and consequently at right angles with the latter. +The piece employed was a 6 in. gun, 35 calibers in +length. The distance of its muzzle from the plates attacked +was 28 ft.</p> + +<p class="ctr"><img src="./images/4-draw.png" width="512" height="154" +alt="Range Illustration"></p> + + +<p>The charge was 44 lb. of brown prismatic powder. +The projectile was a 100 lb. Holtzer shell. Under these +circumstances, the initial velocity was 2,074 ft. and the +energy at the impact was 9,970,396 ft. lb.</p> + + +<p>A beginning was made by firing four shots at each +plate in the bisectrix of the corners. Then the 6 in. gun +was replaced by an 8 in. one, throwing a 209 lb. Firth +projectile, with an energy at the impact of 20,795,000 +ft. lb.</p> + +<p>Each of the plates then received in its center a final +blow from this projectile.</p> + +<p>Our engraving represents the state of the plates after +this last shot.</p> + + +<p class="ctr"><a href="./images/4-range.png"><img src="./images/4-range_th.png" width="600" height="349" +alt="ARMORED PLATE TESTS AT ANNAPOLIS."></a></p> +<p class="ctr">ARMORED PLATE TESTS AT ANNAPOLIS.</p> + +<p>There is no need of being a great expert in questions +of artillery to discover on what side the superiority +is found, and to see that the Cammell plate, +almost entirely in fragments, is absolutely incapable +of protection, while its two competitors are still in a +state to resist.</p> + +<p>In one of our engravings may be seen, too, the state +of the shells after each of the three shots.</p> + +<p class="ctr"><img src="./images/4-shell.png" width="599" height="323" +alt="Shell Illustatrion"></p> + +<p>The commission immediately and unanimously classified +the three plates in the following order of superiority: +(1) Nickel steel; (2) all steel; (3) compound.</p> + +<p>This triumph of French industry merits mention so +much the more in that it was obtained in a series of +experiments made in a foreign country—that is to say, +under indisputable conditions of impartiality.-<i>L'Illustration.</i></p> + +<hr /> + +<a name="ref12"></a><h2>HIGH EXPLOSIVES IN WARFARE.<a name="FN12anchor_1"></a><a href="#FN12_1"><sup>1</sup></a></h2> + +<h3>By Commander F.M. BARBER, U.S.N.</h3> + + +<p>In commencing my paper this evening I desire to +call your attention to the fact that I am dealing with +a subject which, though not theoretical, is still hardly +practical, for as a matter of fact high explosives cannot +be said to have yet been regularly used in warfare, +and I hope you will pardon me if in consequence my +statements appear in some respects unsatisfactory and +my theories unsound. My subject, however, is no more +obscure than future naval warfare generally. All civilized +nations are spending millions of money for fighting +purposes directly in opposition to the higher feelings +of the better class of their inhabitants. The political +atmosphere of Europe is the cause of this, but its +consequence is the development of theoretical plans of +ships which are no sooner commenced than the rapid +march of mechanical, chemical, and electrical science +shows them to be faulty in some particular feature, +and others are laid down only to be superseded in their +turn.</p> + +<p>None of these crafts are obsolete (to use the popular +expression of the day). All are theoretically better +than any which have stood the test of battle; but each +excels its predecessor in some particular feature. The +use of high explosives is the direct cause of the very +latest transformations in marine architecture, and is +destined to work still greater changes; but it will require +a war between the most civilized nations of the +world, and a long war, to either confirm or condemn +the many theoretical machines and methods of destruction +that modern science has produced. I say a war +between the most civilized nations, since it is only they +that can supply the educated intellect that is necessary + +to both attack and defense. Under other circumstances +false conclusions as to weapons and results are +certain to be drawn.</p> + +<p>At the bombardment of Alexandria, the English +armorclads, with their rifled guns, were not nearly as +efficient against the feeble chalk fortifications as our +wooden ships would have been with smooth bore guns. +On the other hand I saw on shore after the bombardment +hundreds of torpedoes and miles of cable that the +Egyptians did not understand how to use. The French +war with China was equally unsatisfactory from a military +point of view. The Chinese at Foochow were annihilated +because the French opened fire first, and the +only shell that penetrated a French ironclad was filled +with lamp black instead of powder. The national riots +that we are accustomed to hear of in South America +are likewise of little instructive value; they buy their +weapons of more civilized people, but there is always +something fatally defective about the tactics pursued +in using them. It may be said in general terms that +in these days of extreme power in fighting machines, +the greater the efficiency the less the simplicity and +the more knowledge required in the care of the weapons. +When powder was merely powder the advice of +the old adage to "trust in God and keep your powder +dry" was ample to maintain the efficiency of the powder +for all purposes; but nowadays if you keep your +powder dry you will burst your gun, and if you keep +your gun-cotton dry you are liable to blow up your +ship.</p> + +<p>It is rather difficult to-day to define what high explosives +are, in contradistinction to gunpowder. Thirty +years ago we could say that powder was a mechanical +mixture and the others were chemical compounds; +but of late years this difference has disappeared.</p> + +<p>The dynamical difference, however, still remains. +Gunpowder in its most efficient form is a slow-burning +composition, which exerts a relatively low pressure and +continues it for a long time and to a great distance. +High explosives, on the contrary, in their most efficient +form, are extremely quick-burning substances, which +exert an enormous pressure within a limited radius. +Ordinary black gunpowder consists of a mechanical +mixture of seventy-five per cent. of saltpeter, fifteen +per cent of charcoal, and ten per cent. of sulphur. +The most important of the high explosives are formed +by the action of nitric acid upon organic substances or +other hydrocarbons, the compound radical NO<sub>2</sub> being +substituted for a portion of the hydrogen in the substance. +The bodies thus formed are in a condition of +unstable equilibrium; but if well made from good material, +they become stable in their instability, very +much like Prince Rupert's drops, those little glass pellets +which endure almost any amount of rough usage; +but once cracked, fly into infinitesimal fragments.</p> + +<p>The power exerted by these nitro-substitution products +is due to the fact that they detonate, <i>i.e.</i>, they +are instantaneously converted into colorless gas at a +very high temperature, and in addition they have almost +no solid residue. Nitro-glycerine actually leaves +none at all, while gunpowder leaves sixty-eight per +cent. The first departure in gunpowder from the old-time +constituents of black powder just mentioned was +for the purpose of obtaining less pressure and slower +<a name="Page_12683" id="Page_12683"></a>combustion than could be produced by mere granulating +or caking. This was accomplished by using +underburned charcoal, together with sugar and about +one and one-half per cent. of water. This is the brown +powder most generally used at present and with satisfactory +results; but the abstraction of its moisture increases +its rapidity of combustion to a dangerous degree, +besides which the underburned charcoal is itself +unstable.</p> + +<p>The next change demanded is smokelessness, and to +accomplish it recourse is had to the high explosive +field, mechanically mixing various substances with +them to reduce and regulate their rapidity of action. +Just now some form of gun-cotton is most in use mixed +with nitrate of ammonia, camphor and other articles. +The tendency of these mixtures is to absorb moisture, +and the gun-cotton in them to decompose, and there is +no smokeless powder which can to-day be considered +successful. Such a powder, however, will undoubtedly +be an accomplished fact in the near future. Military +men seem to be a great deal at variance as to its value +in the field, but there can be no doubt of its value for +naval purposes; it is a necessity forced upon us by the +development of torpedo warfare.</p> + +<p>First came the simple torpedo, at the end of an ordinary +boat's spar. Then came the special torpedo +boat with its great speed, then the revolving cannon +and rapid-fire gun to meet the torpedo boat. At present +the possible rapidity of fire is much greater than +can be utilized, on account of the smoke; hence the +necessity of smokeless powder. Smokelessness is, however, +principally a martial demand that has been made +upon the science of explosives and has attracted public +attention on that account. The commercial demands +for various other properties have been much greater +than the military, and between gunpowder near one +end of the line in point of power and nitro-glycerine +near the other, there are now over 350 different explosives +manufactured, and most of these have been invented +within the last twenty years.</p> + +<p>The simplest application of high explosives in warfare +is in connection with torpedoes, since within the +same bulk a much more efficient substance can be obtained +than gunpowder, and with reasonable care +there is very little danger of premature explosions by +reason of accidental shocks.</p> + +<p>Torpedoes were made by the Chinese many years ago, +they were tried in our war of independence, and also +by the Russians during the Crimean war; but the first +practical and successful use of them as a recognized +weapon was during our war of secession, when thirty-seven +vessels were either sunk or seriously injured by +them. Gunpowder was used in these torpedoes, though +it is stated that attempts were made to use other substances +without success. Since that time all maritime +nations have made a close study of the subject and +have adopted various high explosives, according to the +results of their experiments. In general terms it may +be stated that explosive chemical compounds have +been found more suitable than explosive mixtures, because +of the uniformity of direction in which they exert +their pressure, and from the fact that water does +not injure them. Mixtures may be very powerful, but +they are erratic and require tight cases. In the United +States we use dynamite for harbor mines. It is composed +of seventy-five per cent. nitro-glycerine and +twenty-five per cent. silica; but blasting gelatine and +forcite gelatine will probably be adopted, when they +can be satisfactorily manufactured here, as they are +more powerful. The former is composed of ninety-two +per cent. of nitro-glycerine and eight per cent. of gun-cotton, +and the latter of ninety-five per cent. of nitro-gelatine +and five per cent. unnitrated cellulose.</p> + +<p>For naval use we have adopted gun-cotton as being +the most convenient. In Europe gun-cotton is generally +used for both fixed mines and movable torpedoes; +Russia, Austria, and Italy use blasting gelatine +also.</p> + +<p>In actual warfare but little experience has been had. +Two Peruvian vessels were sunk by dynamite in the +Chili-Peruvian war, one Turk by means of gun-cotton +during the Turco-Russian war of 1877, and two Chinese +by gun-cotton in the Franco-Chinese war of 1884.</p> + +<p>In making experiments to determine the relative +strength of the different explosives under water, very +curious and puzzling results have been obtained. +Nitro-glycerine being the simplest and most complete +in its chemical decomposition, and apparently the +most powerful in air, it was natural to suppose that it +would be the same in submarine work, but it was +found by Gen. Abbot, at Willets Point, after repeated +experiments, as shown in his report of 1881, that it was +not so powerful in its effect by twenty per cent. as +dynamite No. 1, although the dynamite contained +twenty-five per cent. of an absolutely inert substance. +His idea was that it was too quick in its action, and, +since water is slightly compressible, a minute fraction +of time is required in the development of the full force +of the explosive. Gen. Abbot's results for intensity of +action per unit of weight of the most important substances +is as follows:</p> + + +<table align="center" border="1" cellpadding="10" cellspacing="2" summary=""> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><td>Blasting gelatine</td><td>142</td></tr> +<tr><td>Forcite gelatine</td><td>133</td></tr> +<tr><td>Dynamite No 1</td><td> 100</td></tr> +<tr><td>Gun-cotton, wet</td><td>87</td></tr> +<tr><td>Nitro-glycerine</td><td>81</td></tr> +<tr><td>Gunpowder</td><td>20 to 50</td></tr></table> + + +<p>Col. Bucknill, of the Royal Engineers, in his publication +of 1888, gives the following:</p> + +<table align="center" border="1" cellpadding="10" cellspacing="2" summary=""> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><td>Blasting gelatine</td><td>142</td></tr> +<tr><td>Forcite gelatine </td><td> 133</td></tr> +<tr><td>Dynamite No. 1</td><td> 100</td></tr> +<tr><td>Gun-cotton, dry</td><td>100</td></tr> +<tr><td>Gun-cotton, dry</td><td> 80</td></tr> +<tr><td>Gunpowder</td><td>25</td></tr> +</table> + +<p>In both tables dynamite No. 1 is assumed as the +standard of comparison. Col. Bucknill states that his +gun-cotton results differ from Gen. Abbot's, because +he experimented with much larger quantities, viz., +500-pound charges. Gen. Abbot's experiments led him +to believe that an instantaneous mean pressure of +6,500 pounds per square inch would give a fatal blow +to the double bottom of a modern armorclad, and he +developed a formula which gives this blow with blasting +gelatine at the following distances under water, +viz.: + +<table align="center" border="1" cellpadding="10" cellspacing="2" summary=""> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><th> </th><th>Pounds</th></tr> +<tr><td>At 5 feet </td><td> 4</td></tr> +<tr><td> At 10 feet </td><td> 17</td></tr> +<tr><td> At 20 feet </td><td> 67</td></tr> +<tr><td> At 30 feet </td><td> 160</td></tr> +<tr><td> At 40 feet </td><td> 311</td></tr> +</table> + +<p>Col. Bucknill's experiments caused him to believe +that a pressure of 12,000 pounds per square inch is required, +and his formula, which is somewhat different +from Abbot's, gives widely different results at close +quarters, but they approach each other as the distance +increases.</p> + +<p>His results are as follows:</p> + +<table align="center" border="1" cellpadding="10" cellspacing="2" summary=""> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><th> </th><th>Pounds</th></tr> +<tr><td>At 5 feet </td><td> 231/2</td></tr> +<tr><td> At 10 feet </td><td> 75</td></tr> +<tr><td> At 20 feet </td><td> 177</td></tr> +<tr><td> At 30 feet </td><td> 274</td></tr> +<tr><td> At 40 feet </td><td> 369</td></tr> +</table> + +<p>Regarding the comparative effects of gunpowder and the high +explosives, I think Gen. Abbot's estimate of a varying value for +powder is more admissible than the fixed value assigned by Col. +Bucknill. Gunpowder gives a push and detonating compounds a shock; as +the quantities increase, the push reaches farther than the shock. +According to Gen. Abbot, 100 pounds of dynamite No. 1 will have a +destructive horizontal range of 16.3 feet, while the same amount of +gunpowder will only have a range of 3.3 feet. Five hundred pounds of +dynamite, however, will have a horizontal range of 35 feet, and 500 +pounds of gunpowder will have 19.5 feet; the ratio has diminished from +five to two. Whether 6,500 pounds or 12,000 pounds per square inch is +necessary to crush the bottom of an armorclad will depend largely upon +how far apart the frames of the ship are spaced and what other bracing +is supplied, as well as many local circumstances. It is difficult to +judge exactly of these matters. Some four years ago the Italian +government adopted treble bottoms for their heaviest ships as a result +of experiments with seventy-five pounds of gun-cotton (the charge of +an ordinary Whitehead locomotive torpedo) against a caisson which was +a <i>fac-simile</i> of a portion of the proposed ships. Only two of the +bottoms were broken through, and when the space between the two inner +bottoms was filled with coal, only the outer bottom was broken. +According to the formulĉ of either Abbot or Bucknill, there should +have been a local pressure of at least 300,000 pounds per square inch +on the outer skin, and yet judicious interior arrangements rendered it +harmless to the target. It would not, however, be safe to conclude +that the torpedo was thus vanquished; the immediate result was simply +to create a demand for larger locomotive torpedoes for local +application, and but little light was thrown upon the results which +might be anticipated from a large mine at a greater distance, whose +radius of explosive effect would embrace a larger portion of the ship, +and especially if the ship were nearly over the torpedo. The local +effect of a detonation is different from the transmitted shock. +Experiments in England have shown that 500 pounds of gun-cotton at +forty feet below any ship will sink her, and at a horizontal distance +of 100 feet, damage to the interior pipes and machinery is to be +expected.</p> + +<p>The fact that the high explosives are so much heavier +than gunpowder has an important bearing on the size +of the containing case. Their sp. gr. is as follows:</p> + +<table align="center" border="1" cellpadding="10" cellspacing="0" summary=""> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><th> </th><th>Pounds</th></tr> +<tr><td> Nitro-glycerine</td><td>1.6</td></tr> +<tr><td> Blasting gelatine</td><td>1.45</td></tr> +<tr><td> Forcite gelatine </td><td>1.51</td></tr> +<tr><td> Dynamite No. 1</td><td>1.6</td></tr> +<tr><td> Wet gun-cotton</td><td>1.32</td></tr> +<tr><td> Dry gun-cotton</td><td>1.06</td></tr> +<tr><td> Gunpowder</td><td>0.9</td></tr> +</table> + +<p>Their relative efficiency under water per cubic foot, +according to Bucknill, is as follows:</p> + +<table align="center" border="1" cellpadding="10" cellspacing="0" summary=""> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><th> </th><th>Pounds</th></tr> +<tr><td> Blasting gelatine</td><td>1.38</td></tr> +<tr><td> Forcite gelatine</td><td>1.27</td></tr> +<tr><td> Dynamite No. 1</td><td>1.00</td></tr> +<tr><td> Dry gun-cotton</td><td>0.66</td></tr> +<tr><td> Wet gun-cotton</td><td>0.66</td></tr> +<tr><td> Gunpowder</td><td>0.14</td></tr> +</table> + +<p>The wet gun-cotton has twenty-five per cent. of +added water.</p> + +<p>Mines for harbor defense are of two kinds—buoyant and ground. The +buoyant are usually spherical, and contain from 400 to 500 pounds of +explosive. They bring the charge near to the ship's bottom, but are +difficult to manage in a tideway, and can be easily found by dragging. +The ground mines can be made of any size and are not easily found by +dragging, but are of little value in very deep water. They are either +cylindrical or hemispherical in shape, and contain from 500 to 1,500 +pounds of explosive in from thirty to eighty feet of water. Mines of +any kind are exceedingly difficult to render efficient when the water +is over 100 feet deep. On account of the tendency of all high +explosives to detonate by influence or sympathy, and the liability of +the cases to collapse by great exterior pressure, harbor mines are +separated a certain distance, according as they are buoyant or ground, +and according to the nature of the explosive.</p> + +<p>Five hundred pounds buoyant gun-cotton mines require 320 feet +spacing.</p> + +<p>Five hundred pounds buoyant blasting gelatine mines require 450 +feet spacing.</p> + +<p>Six hundred pounds ground gun-cotton mines require 180 feet +spacing.</p> + +<p>Six hundred pounds ground blasting gelatine mines require 230 feet +spacing.</p> + +<p>Of torpedoes, other than those described, we have several modern +varieties; submarine projectiles, submarine rockets, automobile and +controllable locomotive torpedoes. The first two varieties, though +feasible, are not developed and have not yet advanced beyond the +experimental stage. Of the automobile, we have the Whitehead, +Swartzkopf and Howell. The first two are propelled by means of +compressed air and an engine; the last by the stored-up energy of a +heavy fly-wheel. Generally speaking, they are cigar-shaped crafts, +from 10 to 18 feet long and 15 to 17 inches in diameter, capable of +carrying from 75 to 250 pounds of explosive at a rate of 25 to 30 +knots for 400 yards, at any depth at which they may be set. Of the +controllable locomotive torpedoes, the three representative + +types are the Patrick, Sims and Brennan. They are in general terms +cigar boats, about 40 feet long and 2 feet in diameter, carrying +charges of 400 pounds of explosive. The Patrick and Sims are +maintained at a constant depth under water by means of a float. The +Brennan has diving rudders like a Whitehead or a Howell. The Patrick +is driven by means of carbonic acid gas through an engine, and is +controlled by an electric wire from shore. The Sims is driven by +electricity from a dynamo on shore through a cable to an electric +engine in the torpedo. The Brennan is driven and controlled by means +of two fine steel wires wound on reels in the torpedo, the reels being +geared to the propeller shafts. The wires are led to corresponding +reels on shore, and these are rapidly revolved by means of an engine. +A brake on each shore reel controls the torpedo. The speed of all +these torpedoes is about 19 knots, and their effective range one +mile.</p> + +<p>A Whitehead was successfully used in the Turco-Russian war of 1877. +The Turkish vessel previously mentioned was sunk by one.</p> + +<p>Blasting gelatine, dynamite and gun-cotton are capable of many +applications to engineering purposes on shore in time of war, and in +most cases they are better than powder. They received the serious +attention of French engineers during the siege of Paris, and were +employed in the various sorties which were made from the city, in +throwing down walls, bursting guns, etc. An explosive for such +purposes, and indeed for most military uses, should satisfy the +following conditions:</p> + +<blockquote> +<p>(1) Very shattering in its effects.</p> + +<p>(2) Insensible to shocks of projectiles.</p> + +<p>(3) Plastic.</p> + +<p>(4) Easy and safe to manipulate.</p> + +<p>(5) Easy to insert a fuse.</p> + +<p>(6) Great stability at all natural temperatures and +when used in wet localities. +</blockquote> + +<p>Neither blasting gelatine, dynamite nor gun-cotton +fulfills all these conditions; but they satisfy many of +them and are more powerful than other substances. +For the destruction of walls, trees, rails, bridges, etc., +it is simply necessary to attach to them small bags of +explosive, which are ignited by means of blasters' fuse +and a cap of fulminate of mercury, or by an electric +fuse.</p> + +<p>We now come to the application of high explosives +to warfare in the shape of bursting charges for shells. +This is the latest phase of the problem, and it is undoubtedly +fraught with the most important consequences +to both attack and defense. Difficult as it +has been to obtain an exact estimate of the force of +different explosives under water, the problem is far +greater out of the water and under the ordinary conditions +of shell fire; the principal obstacle being in the +fact that it is physically impossible to control the force +of large quantities in order to measure it, and small +quantities give irregular results. Theoretically, the +matter has been accomplished by Berthelot, the head +of the French government "Commission of Explosives," +by calculating the volume of gas produced, +heat developed, etc.; and this method is excellent for +obtaining a fair idea of the specific pressure of any +new explosive that may be brought forward, and determining +whether it is worth while to investigate it +further; but the explosives differ so much from each +other in point of sensitiveness, weight, physical condition, +velocity of explosive wave, influence of temperature +and humidity, that we cannot determine from +mere theoretical considerations all that we would like +to know. Various methods of arriving at comparative +values have been tried, but the figures are very +variable, as will be seen by the following tables. +Berthelot's commission, some ten years ago, exploded +ten to thirty grammes of each in 300 pound blocks +of lead and measured the increased size of the hole thus +made. The relative result was:</p> + +<table align="center" border="1" cellpadding="10" cellspacing="2" summary=""> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><td>No. 1 dynamite</td><td>1.0</td></tr> +<tr><td>Dry gun-cotton</td><td>1.17</td></tr> +<tr><td>Nitro-glycerine</td><td>1.20</td></tr> +</table> + +<p>Powder blew out and could not be measured.</p> + +<p>Mr. R.C. Williams, at the Boston Institute of Technology, +in the winter of 1888 and 1889, tried the same method, but +used six grammes in forty-five pound blocks +of lead. He obtained a relative result of—</p> + +<table align="center" border="1" cellpadding="10" cellspacing="2" summary=""> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><td>No. 1 dynamite</td><td>1.0</td></tr> +<tr><td>Dry gun-cotton</td><td>1.37</td></tr> +<tr><td>Nitro-glycerine</td><td>2.51</td></tr> +<tr><td>Explosive gelatine</td><td>2.57</td></tr> +<tr><td>Forcite gelatine</td><td>2.7</td></tr> +<tr><td>Warm nitro-glycerine</td><td> 2.7</td></tr> +<tr><td>Gunpowder</td><td>0.1</td></tr> +</table> + +<p>The powder gave great trouble in this case, also, by +blowing out.</p> + +<p>M. Chalon, a French engineer, obtained some years +ago, with a small mortar, firing a projectile of thirty +kilos and using a charge of ten grammes of each explosives, +the following ranges:</p> + +<table align="center" border="1" cellpadding="10" cellspacing="2" summary=""> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><th></th><th>Meters.</th></tr> +<tr><td>Blasting powder</td><td>2.6</td></tr> +<tr><td>No. 1 dynamite</td><td>31.4</td></tr> +<tr><td>Forcite of 75 per cent. N.G.</td><td>43.6</td></tr> +<tr><td>Blasting gelatine</td><td>45.0</td></tr> + +</table> + +<p>Roux and Sarran obtained by experiments in bursting +small bomb shells the following comparative +strengths of ranges:</p> + +<table align="center" border="1" cellpadding="10" cellspacing="2" summary=""> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><td>Powder</td><td>1.0</td></tr> +<tr><td>Gun-cotton</td><td>6.5</td></tr> +<tr><td>Nitro-glycerine</td><td>10.0</td></tr> +</table> + +<p>In actual blasting work the results vary altogether +with the nature of the material encountered, and with +the result that is desired to be accomplished, viz., +throwing out, shattering, or mere displacement.</p> + +<p>Chalon gives for quarrying:</p> + +<table align="center" border="1" cellpadding="10" cellspacing="2" summary=""> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><td>Powder</td><td> 1</td></tr> +<tr><td>Dynamite No. 2, containing 50 per cent. nitro-glycerine</td><td>3</td></tr> +</table> + +<p>For open blasting:</p> + +<table align="center" border="1" cellpadding="10" cellspacing="2" summary=""> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><td>Dynamite No. 3, containing 30 per cent. N.G.</td><td>1.0</td></tr> +<tr><td>Dynamite No. 1, containing 75 per cent. N.G.</td><td>2.5</td></tr> +<tr><td>Blasting gelatine</td><td>3.5</td></tr> +</table> + + +<p>For tunneling:<a name="Page_12684" id="Page_12684"></a></p> + +<table align="center" border="1" cellpadding="10" cellspacing="2" summary=""> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><td>Dynamite No. 3, containing 30 per cent. N.G</td><td>1</td></tr> +<tr><td>Dynamite No. 1, containing 75 per cent. N.G</td><td>3</td></tr> +<tr><td>Explosive gelatine</td><td>19</td></tr> +</table> + +<p>Finally Berthelot's theoretical calculations give a +specific pressure of—</p> + +<table align="center" border="1" cellpadding="10" cellspacing="2" summary=""> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><td>Powder</td><td>1</td></tr> +<tr><td>Dynamite</td><td>13</td></tr> +<tr><td>Gun-cotton</td><td>14</td></tr> +<tr><td>Nitro-glycerine</td><td>16</td></tr> +<tr><td>Blasting gelatine</td><td>17</td></tr> +</table> + +<p>It will be observed that the practical results vary +largely from the theoretical values, but they seem to +indicate that gun-cotton and No. 1 dynamite are +very nearly equal to each other, and that in the +nitro-glycerine compounds, except where gun-cotton +is added, the force appears to be nearly in proportion +to the nitro-glycerine contained. From the foregoing +it seems fair to estimate roughly the values of bursting +charges of shells as follows:</p> + +<table align="center" border="1" cellpadding="10" cellspacing="2" summary=""> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><td>Powder</td><td>1</td></tr> +<tr><td>Gun-cotton and dynamite</td><td>6 to 10</td></tr> +<tr><td>Nitro-glycerine</td><td>13 to 15</td></tr> +<tr><td>Blasting gelatine</td><td>15 to 17</td></tr> +</table> + +<p>Attention has been turned in Europe for more than +thirty years toward firing high explosives in shells; but +it is only within very late years that results have been +reached which are claimed as satisfactory, and it is +exceedingly difficult to obtain reliable accounts even of +these. Dynamite was fired in Sweden in 1867 in small +quantities, and a few years later it was fired in France. +But two difficulties soon presented themselves. If the +quantity of nitro-glycerine in dynamite was small, it +could be fired in ordinary shells, but the effect was no +better than with gunpowder. If the dynamite was +stronger in nitro-glycerine, it took but a small quantity +to burst the gun.</p> + +<p>As early as 1864, dry gun-cotton was safely fired in +shells in small quantities, but when a sufficient quantity +to fill the shell cavity was used, the gun burst. +Some few years ago it was found that if the gun-cotton +was either wet or soaked in paraffin, it could be fired +with safety from powder guns in ordinary shells, provided +the quantity was small in proportion to the total +weight of the shell—say five or six per cent. But a +new difficulty arises from the fact that it breaks the +shell up into very small pieces, and it is an unsettled +question among artillerists whether more damage is +done to an enemy by breaking a shell into comparatively +large pieces and dispersing them a long distance +with a bursting charge of powder, which has a propulsive +force, or by breaking it with a detonating compound +into fine pieces, which are not driven nearly so +far. When used against troops there is also the objection +to the high explosive shell that it makes scarcely +any smoke in bursting, and smoke at this point is useful +to the artillerist in rectifying his aim.</p> + +<p>In the matter of shells for piercing armor, however, +there are no two opinions regarding the nature of the +bursting charge. To pierce modern armor at all a shell +must be made of forged steel, so thick that the capacity +of the cavity for the bursting charge is reduced to one-fourth +or one-fifth of what it is in the common shell; +the result is that a charge of powder is frequently not +powerful enough to burst the shell at all; it simply +blows the plug out of the filling hole in the rear. In +addition it is found that in passing through armor, the +heat generated is so great that the powder is prematurely +ignited.</p> + +<p>If then we can fill the small cavity in the shell with +an explosive which will not ignite prematurely, and yet +will burst the shell properly after it has passed through +the armor, the problem will be solved. Wet or paraffined +gun-cotton can be made sluggish enough to +satisfy the first condition; but at present the difficulty +is to make it explode at all. The more sluggish the +gun-cotton, the more powerful must be the fuse exploders +to detonate it, and such exploders are themselves +liable to premature ignition in passing through the armor.</p> + +<p>The Italians and Germans claim to have accomplished +the desired result up to a thickness of five inches of +armor; gun-cotton and fuse both working well. But +the English authorities say that no one has yet +accomplished it. The Austrians claim to have succeeded +in this direction within the last year with a new explosive +called ecrastite (supposed to be blasting gelatine +combined with sulphate or hydrochlorate of ammonia, +and claimed to be one and one-half times as +powerful as dynamite).</p> + +<p>With a gun of 8.24 inches caliber and an armor-piercing +shell weighing 206.6 pounds, containing a bursting +charge of 15.88 pounds of ecrastite, they are said to +have perforated two plates four inches thick, and entered +a third four-inch plate where the shell exploded. +There is a weak point in this account in the fact that +the powder capacity of the shell is said to be 4.4 pounds.</p> + +<p>This amount is approximately correct, judging from +our own eight-inch armor-piercing shell, but if this is +true, there could not have been more than nine pounds +of ecrastite in the shell instead of sixteen, or else there +is an exceedingly small proportion of blasting gelatine +in ecrastite, and if that is the case it is not one and +one-half times as powerful as dynamite. If it is weak +stuff, it is probably insensitive, and even if it were +strong, one swallow does not make a summer. The +English fired quantities of blasting gelatine from a +two-inch Nordenfeldt gun in 1884, but when they +tried it in a seven-inch gun, in 1885, they burst the +gun at once.</p> + +<p>I have only analyzed this Austrian case, because the +statement is taken from this year's annual report of +the Office of Naval Intelligence, which is an excellent +authority, and to illustrate the fact that of the thousands +of accounts, which we see in foreign and domestic +newspapers, concerning the successful use of high +explosives in shells, fully ninety per cent. are totally +unreliable. In many cases they are in the nature of a +prospectus from the inventors of explosives or methods +of firing, who are aware of the fact that it is almost +impossible to dispute any statements that they may +choose to make regarding the power of their new compounds, +and thinking, as most of them do, that power +alone is required.</p> + + +<p>Referring to the qualities that I have previously +cited as being required in a high explosive for military +purposes, it is sooner or later found that nearly all the +novelties proposed lack some of the essentials and +soon disappear from the advertising world only to be +succeeded by others. The most common defect is lack +of keeping qualities. They will either absorb moisture +or will evaporate; or further chemical action will +go on among the constituents, making them dangerously +sensitive or completely inert, or they will separate +mechanically according to their specific gravities.</p> + +<p>For further clearness on the subject of the shell +charges which have so far been discussed, the following +table is added of weight and sizes of shells for +United States naval guns, with their bursting charges +of powder:</p> + +<pre> + 6-inch com. cast steel shell 31/2 to 4 cal. long, wt. 100 lb., charge 6 lb. + 8 " " " " " 250 " 141/2 lb. +10 " " " " " 500 " 27 " +12 " " " " " 850 " 45 " +</pre> + +<p class="ctr">ARMOR-PIERCING FORGED STEEL SHELL.</p> + +<pre> + 6-inch, 3 calibers long, weight 100 lb, charge 11/2 lb. + 8 " " " 250 " 3 " + 10 " " " 500 " 51/2 " + 12 " " " 850 " 11 " +</pre> + +<p>The chief efficiency of small quantities of high explosives +having reduced itself to the case of armor-piercing +projectiles, it next became evident that there +was an entirely new field for high explosives into which +powder had entered but little, and this was the introduction +of huge torpedo shells, which did nor rely for +their efficiency upon the dispersion of the pieces of the +shell, but upon the devastating force of the bursting +charge itself upon everything within the radius of its +explosive effect. It is in this field that we may look +for the most remarkable results, and it is here that the +absolute power of the explosive thrown is of the utmost +importance, provided that it can be safely used. +Attention was at once turned in Europe to the manufacture +of large projectiles with great capacity for +bursting charges, and it has resulted in the production +of a class of shells 41/2 to 6 calibers long, with walls +only O.4 of an inch thick. (If they are made thinner, +they will swell and jam in the gun when fired.)</p> + +<p>These shells are used in long guns up to 6 and 81/2 +inches caliber, and in mortars up to 11.2 inches. They +are made from disks of steel, 3 to 4 feet in diameter +and 1 inch thick, and are forced into shape by hydraulic +presses. The base is usually screwed in, but some +of the German shell are made in two halves which screw +together. The Italians were the first in this new field +of investigation, but the Germans soon followed, and +after trying various materials were at length reasonably +successful with gun-cotton soaked in paraffin. +Their 8.4 inch mortar shells of 5 calibers contain 42 +pounds; those of 6 calibers contain 57 pounds; and the +11.2 inch mortar shells of 5 calibers contain 110 pounds.</p> + +<p>The projectile velocity used with the mortars is +about 800 f.s. The effect of these shells against ordinary +masonry and earth fortifications is very great. +The charge of forty-two pounds has broken through a +masonry vault of three feet four inches thick, covered +with two feet eight inches of cement and with three +to five feet of earth over all. The shell containing +fifty-seven pounds, at a range of two and one-half +miles, broke through a similar vault covered with ten +feet of earth; but with seventeen feet of earth the +vault resisted. In 1883, experiments at Kummersdorf +showed that a shell containing the fifty-seven pound +charge would excavate in sand a crater sixteen feet in +diameter and eight feet deep, with a capacity of twenty-two +cubic yards. The Italians have had similar experiences; +but it is notable that in both Germany and +Italy several guns and mortars have burst. The velocity +in the guns is not believed to exceed 1,200 to +1,300 f.s., and it is not thought that the quantity of +gun-cotton is as great in the gun shells as in the mortars. +I have lately been informed on good authority +that the use of gun-cotton shells has been abandoned +in the German navy as too dangerous.</p> + +<p>The French, in their investigations in this field, found +gun-cotton too inconvenient, and decided upon melenite. +This substance has probably attracted more attention +in the military world than all others combined, on +account of the fabulous qualities that have been ascribed +to it. Its composition was for a long time entirely a +secret; but it is now thought to consist principally of +picric acid, which is formed by the action of nitric +acid upon phenol or phenyillic alcohol, a constituent +of coal tar. The actual nature of melenite is not +positively known, as the French government, after buying +it from the inventor, Turpin, are said to have added +other articles and improved it. This is probable, +since French experiments in firing against a partially +armored vessel, the Bellequense, developed an enormous +destructive effect, while the English, who afterward +bought it, conducted similar experiments against the +Resistance, and obtained no better results than with +powder. The proof that the Bellequense experiments +were deemed of great value by the French lies in the +fact that they immediately laid down a frigate—Dupuy +de Lome—in which four-inch armor is used, not +only on the side, but about the gun stations, to protect +the men; this thickness having been found sufficient +to keep out melenite shell. In most armorclads, the +armor is very heavy about the vitals, but the guns are +frequently much exposed.</p> + +<p>The best authenticated composition for melenite +consists of picric acid, gun cotton and gum arabic, and +lately it is stated that the French have added cresilite +to it. Cresilite is another product of coal tar. Melenite +is normally only three times as strong as gunpowder; +but it is said to owe its destructive qualities in +shells to the powerful character of the exploder which +ignites it. It has been known for some years that all +explosives (including gunpowder) are capable of two +orders of explosion according as they are merely ignited +or excited by a weak fuse or as they are powerfully +shocked by a more vigorous excitant. Fulminate of +mercury has been found most serviceable for the latter +purpose. With melenite the French have reproduced +all the results that the Germans have effected with +gun-cotton and have found that a shell containing 119 +pounds of it will penetrate nearly ten feet of solid cement, +but will not penetrate armored turrets six to +eight inches thick. The French claim that melenite +has an advantage over gun-cotton in not being so dangerous +to handle and being insensible to shock or friction, + +and they have obtained a velocity of 1,300 f.s. +with the 88 inch mortar and claim to have obtained +2,000 f.s. in long guns up to 62 inch caliber. However +this may be, they are known to have had severe accidents +at the manufactory at Belfort and at least one +56 inch gun was burst at the Bellequense experiments +in firing a sixty-six pound shell containing twenty-eight +pounds of melenite. The French are said to +have large quantities of melenite shells in store, but +they are not issued to service.</p> + +<p>Probably one reason why we have so many conflicting +yet positive accounts of great successes in Europe +with torpedo shells is because each nation wishes its +neighbors to think that it is prepared for all eventualities, +and they are obliged to keep on hand large quantities +of some explosive, whether they have confidence +in it or not. Fortunately we are not so situated, but +singularly enough what we have done in the field of +high explosive projection has been accomplished by +private enterprise, and we have attacked the problem +at exactly the opposite point from which European +nations have undertaken it. While they have assumed +that the powder gun with its powerful and relatively +irregular pressures was a necessity and have endeavored +to modify the explosive to suit it, we have taken +the explosive as we have found it, and have adapted +the gun to the explosive. At present the prominent +weapon in this new field is the pneumatic gun, but it +is obvious that steam, carbonic acid gas, ammonia or +any other moderate and regulatable pressure can be +used as well as compressed air; it is merely a question +of mechanical convenience.</p> + +<p>In throwing small quantities of certain high explosives, +powder guns can be used satisfactorily, but when +large quantities are required, the mechanical system +of guns possess numerous advantages. All the high +explosives are subject to premature detonation by +shock; each of them is supposed to have its own peculiar +shock to which it is sensitive; but what this shock +may be is at present unknown. We do know, however, +that premature explosions in guns are more liable +to occur when the charge in the shell is large than when +it is small. This is due to the fact that when the gun +is fired, the inertia of the charge in the shell is overcome +by a pressure proportional to the mass and acceleration, +which pressure is communicated to the shell charge by +the rear surface of the cavity, and the pressure per +unit of mass will vary inversely as this surface. If, +then, the quantity of explosive in the shell forms a +large proportion of the total weight of the shell, we +approach in powder guns a condition of shock to it +which is always dangerous and frequently fatal. The +pressure behind the projectile varies from twelve to +fifteen tons per square inch, but it is liable to rise to +seventeen and eighteen tons, and in the present state of +the manufacture of gunpowder we cannot in ordinary +guns regulate it nearer than that. It is not a matter +of so much importance so far as the guns are concerned, +when using ordinary projectiles, as the gun +will endure a pressure of from twenty-five to thirty +tons per square inch; but with high explosives in the +shell it is a vitally serious matter. From all I can learn +regarding European practice, it appears that not only +are the explosives made sluggish, but the quantity seldom +exceeds thirty per cent. of the weight of the shell, +and the velocities, notwithstanding, are kept very low. +In the pneumatic gun the velocity is low also, but so is +the pressure in the gun. The pressure in the firing +reservoir is kept at the relatively low figure of 1,000 +pounds per square inch or less, and the air is admitted +to the chamber of the gun by a balance valve which +cuts off just the quantity of air (within a very few +pounds) that is required to make the shot. The gun +is long, and advantage is taken of the expansion of the +air. In no case can the pressure rise in the gun beyond +that in the reservoir.</p> + +<p>Up to the present time there have been no accidents +in using the most powerful explosives in their natural +state, and in quantities over fifty per cent. of the +weight of the projectile. I have seen projectiles +weighing 950 pounds, and containing 500 pounds of +explosives (300 pounds of the blasting gelatine and 200 +pounds of No. 1 dynamite) thrown nearly a mile and +exploded after disappearing under water. According +to Gen. Abbot's formula such a projectile would have +sunk any armorclad floating within forty-seven feet of +where it struck. Apparently there is no limit to the +percentage of explosive that can be placed in the shell +except the mechanical one of having the walls thick +enough to prevent being crushed by the shock of discharge. +In the large projectiles a transverse diaphragm +is introduced to strengthen the walls and to +subdivide the charge.</p> + +<p>The development of the pneumatic gun has been attended +with some other important discoveries, which +may be of interest. It is well known that mortar fire +is very inaccurate, except at fixed long distances, in +consequence of the high angle, the slowness of flight +of the projectile, the variability of the powder pressure, +and the inability to change the elevation and the +charge of powder rapidly. In the pneumatic gun, the +complete control of the pressure remedies the most important +of the mortar's defects and makes the fire accurate +from long ranges down to within a few yards of +the gun. It is obvious that the pressure can be usefully +controlled in two ways: (1) by keeping the elevation +of the gun fixed and using a valve that can be set +to cut off any quantity of air, according to the range +desired; (2) by keeping the pressure in the reservoir +constant, and using a valve which will cut off the same +quantity of air every time, changing the elevation of +the gun according to the distance. Another important +discovery consists in the application of subcalibered +projectiles for obtaining increased range.</p> + +<p>The gun is smooth-bored and a full-sized projectile is +a cylinder with hemispherical ends, to the rear of which +is attached a shaft having metal vanes placed at an +angle, which causes the projectile to revolve round its +longer axis during flight. A subcalibered projectile, +however, being of less diameter than the bore of the +gun, has the vanes on its exterior, and is held in the +axis of the gun by means of gas checks which drop off +as the projectile leaves the muzzle. The shock to the +explosive is, of course, greater than in the full-sized +projectile, but the increase can be calculated, and so +far a dangerous limit has not been reached. From +the fifteen-inch gun with a pressure of 1,000 pounds +per square inch and a velocity of about 800 f.s., a +range of 4,000 yards has been obtained at an elevation +of 30° 20, with a ten-inch subcalibered projectile, about +<a name="Page_12685" id="Page_12685"></a>eight calibers long and weighing 500 pounds. This +projectile will contain 220 pounds of blasting gelatine. +With improved full-sized projectiles weighing 1,000 +pounds, a range of 2,500 yards will doubtless be obtained.</p> + +<p>At elevations below 15° these long projectiles are +liable to ricochet, and what is now wanted is a projectile +which will stay under water at all angles +of fall and will run parallel to the surface like a +locomotive torpedo. Such a projectile has yet to be +invented; but I have seen a linked shell, which has been +experimented with from a nine-inch powder gun, that +partially meets this condition. It is made of several +sections united by means of rope or electric wire in +lengths of 100 to 150 feet. When fired all sections remain +together for some distance; the rear section then first +begins to separate; then the next, and so on. It is +primarily intended to envelop an enemy's vessel, and +to remedy the present uncertainty of elevation in a +gun mounted in a pitching boat; but it is found that +when it strikes the water in its lengthened out condition, +it will neither dive nor ricochet, but will continue +for some distance just under the surface until all momentum +is lost, when it will sink. This projectile is at +present crude, and has never been tried loaded, but it +will probably be developed into something useful in +time.</p> + +<p>I have confined my remarks in the foregoing discussion +principally to such methods of using high explosives +in shells as have proved themselves successful beyond +an experimental degree, and practically they reduce +themselves to two, viz., using a sluggish explosive +in small quantities from an ordinary powder gun, and +using any explosive from a pneumatic or other mechanical +gun. Naturally, the success of the latter +method will soon induce the manufacture of powders +having an abnormally low maximum pressure. There is +undoubtedly a field for the use of such powders in connection +with an air space in the gun to still further regulate +the pressure; but nothing of this sort has yet +been attempted. Many methods of padding the shell +have been devised for reducing the shock in powder +guns, but the variability of the powder pressure is too +great to have yet rendered any such method successful. +A method was patented by Gruson in Germany of filling +a shell with the two harmless constituents of an +explosive and having them unite and explode by means +of a fulminate fuse on striking an object. He used for +the constituents nitric acid and dinitro-benzine, and +was quite successful; but the system has not met with +favor, on account of the inconvenience. The explosive +was about four times as powerful as gunpowder.</p> + +<p>That the advantage of using the most powerful explosives +is a real one can be easily shown. The eight +inch pneumatic gun in New York harbor, with a projectile +containing fifty pounds of blasting gelatine and +five pounds of dynamite, easily sunk a schooner at 1,864 +yards range from the torpedo effect of the shell falling +alongside it.</p> + +<p>This same shell, if filled with gunpowder, would +have contained but twenty-five pounds, and have had +but one-ninth the power.</p> + +<p>The principal European nations are now building +armored turrets sunk in enormous masses of cement, +as a result of their experiences with gun-cotton and +melenite. The fifteen inch pneumatic projectile, +which I described as being capable of sinking an +armorclad at forty-seven feet from where it struck, +would have been capable of penetrating fifty feet of +cement had it struck upon a fortification. It was not +only a much larger quantity of high explosive than +Europeans have experimented with, but the explosive +itself is probably more than twice as strong as their +gun-cotton and five or six times as strong as their +melenite. In the plans of Gen. Brialmont, one of the +most eminent of European engineers, he allows in his +fortifications about ten feet of cement over casements, +magazines, etc. It is evident that this is insufficient +for dynamite shells such as I have described.</p> + +<p>At Fort Wagner, a sand work built during our war, +Gen. Gillmore estimated that he threw one pound of +metal for every 3.27 pounds of sand removed. He fired +over 122,230 pounds of metal, and one night's work +would have repaired the damage. The new fifteen +inch pneumatic shell will contain 600 pounds of blasting +gelatine, and judging from the German experiments +at Kummsdorf, which I have cited, one of these +fifteen inch shells would throw out a prodigious quantity +of sand; either 500 pounds to one of shell, or 2,000 +pounds to one of shell, according as the estimate of +Gen. Abbot or of Capt. Zalinski is used. The former +considers that the radius of destructive effect increases +as the square root of the charge; the latter that the +area of destructive effect for this kind of work is directly +proportional to the charge.</p> + +<p>The effect of the high explosives upon horizontal +armor is very great; but we have yet to learn how to +make it shatter vertical armor. No fact about high +explosives is more curious than this, and there is no +theory to account for it satisfactorily. As previously +stated, the French have found that four inches of vertical +armor is ample to keep out the largest melenite +shells, and experiments at Annapolis, in 1884, showed +that masses of dynamite No. 1, weighing from seventy-five +to 100 pounds, could be detonated with impunity +when hung against a vertical target composed of a +dozen one inch iron plates bolted together.</p> + +<p>In conclusion, I may say that in this country we are +prone to think that the perfection of the methods of +throwing high explosives in shell is vastly in favor of +an unprotected nation like ourselves, because we could +easily make it very uncomfortable for any vessels that +might attempt to bombard our sea coast cities.</p> + +<p>This is true as far as it goes, but unfortunately the +use of high explosives will not stop there. I lately had +explained to me the details of a system which is certainly +not impossible for damaging New York from the +sea by means of dynamite balloons. The inventor +simply proposed to take advantage of the sea breeze +which blows toward New York every summer's afternoon +and evening. Without ever coming in sight of +land, he could locate his vessel in such a position that +his balloons would float directly over the city and let +fall a ton or two of dynamite by means of a clock work +attachment. The inventor had all the minor details +very plausibly worked out, such as locating by means +of pilot balloons the air currents at the proper height +for the large balloons, automatic arrangements for +keeping the balloon at the proper height after it was +let go from the vessel, and so on. His scheme is nothing + +but the idea of the drifting or current torpedo, +which was so popular during our war, transferred to +the upper air. An automatic flying machine would be +one step farther than this inventor's idea, and would +be an exact parallel in the air to the much dreaded +locomotive water torpedo of to-day. There seems to +be no limit to the possibilities of high explosives when +intelligently applied to the warfare of the future, and +the advantage will always be on the side of the nation +that is best prepared to use them.</p> + +<a name="FN12_1"></a><a href="#FN12anchor_1">[1]</a><div class="note">A lecture delivered before the Franklin Institute, Philadelphia, November 28, 1890. From the <i>Journal</i> of the Institute.</div> + +<hr /> + +<a name="ref19"></a><h2>THE MANUFACTURE AND USE OF +PLASTER OF PARIS.</h2> + +<p>It has long been a familiar fact that gypsum yields +on baking a material which possesses the power of setting +with water to a firm mass, this setting being accomplished +much more quickly than is the case with +mortar.</p> + +<p>The explanation of the setting of plaster was first +given by Lavoisier, who pointed out that gypsum is +an hydrated salt, and that the set plaster is in fact +gypsum reformed, the change brought about by baking +being merely loss of water of crystallization. The +beds of gypsum of most importance both formerly and +at the present time in the plaster manufacture occur +in the neighborhood of Paris in the lower tertiary formation. +Different beds differ (1) in respect of character +and quantity of admixed materials and (2) in the structure +of the gypsum itself. With regard to the first +point, some deposits contain a notable proportion of +carbonate of lime, a fact which under certain circumstances +may considerably influence the character of +the plaster. In the matter of structure two principal +varieties occur (1) granular and (2) fibrous. Further, +hardness of the granular kind varies considerably. +These differences of structure in the original material +appear to exercise an influence on the properties of the +plaster. Thus according to Payen the plaster formed +from the granular variety sets more gradually than +that derived from the fibrous, and forms a denser mass. +The softer kinds of the granular gypsum are those +principally used in the production of plaster for the +moulds of potteries.</p> + +<p>In the old fashioned process which is still employed +for making the common kinds of plaster, the material +is exposed to the direct action of flame. Large lumps +are placed in the lower part of the furnace, above them +smaller lumps, and, after the heating has been carried +on for some time, finely divided material is filled in at +the top. The outer portion of the larger lumps is +always overburnt, and in the upper part of the furnace +the presence of shining crystalline particles generally +indicates the fact that some gypsum has remained unchanged. +Provided that the amount of unburnt and +overburnt material does not exceed about 30 per cent. +of the total, the plaster is suitable for many applications.</p> + +<p>It was early observed that set plaster could be revivified +by a second baking, but attempts in this direction +were not uniformly successful, it being found that the +dehydrated substance in some cases refused to set with +water. It behaved in fact similarly to the natural anhydrous +calcium sulphate which is unaffected by water. +These failures were found to be due to the employment +of too high a temperature, and such plaster was termed +<i>dead burnt</i>. Although this fact was ascertained long +ago, yet ignorance of what had already been done has +probably been the cause of many disappointments in +attempts at revivification which have been made from +time to time by persons unacquainted with the history +of the subject.</p> + +<p>The view generally adopted with regard to the theory +of these processes is that plaster consists of anhydrous +calcium sulphate, CaSO<sub>4</sub>,in a condition probably +amorphous, different from that of natural crystallized +CaSO<sub>4</sub>, known to mineralogists under the name of anhydrite. +By the influence of a high temperature it +appears probable that a molecular change is gradually +induced with production of a crystalline structure, and +probably an increase of specific gravity, resulting in +the artificial reproduction of the mineral anhydrite. +No determination appears to have been published of +the specific gravity of plaster prepared by complete +baking at a low temperature. The theory is, however, +confirmed by the results obtained by workers on the +subject of mineralogical synthesis, who have shown +that the material which has been produced at high +temperatures has the specific gravity and other physical +properties of the mineral anhydrite.</p> + +<p>It was formerly supposed that plaster prepared by +baking at a temperature above 300 degrees loses completely +its power of setting. Later observations, however, +as those of Landrin, negative this view. Between +300 degrees and 400 degrees Landrin obtained plasters +setting almost instantaneously when mixed with a +small amount of water. When the temperature employed +approached 400 degrees, the set plaster was +softer, but the setting still took place quickly. These +observations appear to show that the change to anhydrite +is a very gradual process at temperatures below +a red heat.</p> + +<p>Reference has been made to the differences in (1) time +of setting of plaster and (2) in hardness of the resulting +material. Both of these properties are affected by +the mode of baking. The hardest material is frequently +obtained from the quick-setting plasters, but for +certain purposes this rapidity in setting is of great +practical inconvenience. Thus the moulder in pottery +work must have leisure to fill in every detail of a design +often complicated and intricate before the material +with which he is working becomes intractable. Thus +for many of the more refined purposes to which plaster +is applied, extreme hardness in the set plaster is of less +vital importance than a convenient period of setting. +On the other hand, plasters which set very slowly give +as a rule too soft a material, as well as being inconvenient +in use. Plasters which hit off the happy medium +are alone suitable for the work of the potter. The +finer varieties of plaster prepared especially for use in +potteries are obtained by a treatment which differs in +many respects from that described above for the +commoner kinds. In the first place, the direct contact +of fuel or even flame is avoided, since this reduces +some of the sulphate to sulphide of calcium, the presence +of which is in many respects objectionable. +Secondly, it is necessary that there should be a better +control over the temperature, since, as has been seen, +if the heating be carried too far the plaster, if not partially + +dead burnt, will set too quickly for the particular +purpose to which it is to be put.</p> + +<p>The arrangement employed in France is known as +the <i>four a boulanger</i>, or baker's furnace. The temperature +attained in the furnace itself never exceeds low +redness. The material preferred is the softer kind of +the granular variety of gypsum. This is put in in pieces +of about 21/2 inches in thickness. After the baking +several lumps are broken up and examined to see that +there are no shining crystalline particles, which would +indicate that some of the gypsum had remained unchanged. +Before use the plaster is ground very fine. +This point is of considerable practical importance. +The consistency attained should be such that the material +may be rubbed between the finger and thumb +without any feeling of grittiness. Should there be +particles of a size to be characterized as "grit," these +will after use appear at the surface of the mould, with +the result that the mould will have to be abandoned +long before it is really worn out, <i>i.e.</i>, before the details +have lost their sharpness.</p> + +<p>It is manifestly of considerable practical importance +to understand the conditions which determine the time +of the setting up of plaster. According to Payen, the +rapidity of setting, provided the plaster has dehydrated +at a temperature sufficiently low, depends entirely +on the structure of gypsum employed. Thus, according +to him, the fibrous kinds gives a plaster setting almost +instantaneously. The water, he says, penetrates the +material freely, setting takes places almost simultaneously +throughout the mass. The hydration of each +particle is accompanied by an expansion, and under +the conditions specified, this expansion being unresisted +takes place to the maximum extent, with the result +of leaving cavities between the crystals, and producing +a set plaster of less coherence and density. On +the other hand, where granular crystalline gypsum has +been used, setting begins at the surface of each group +of crystals before the water has penetrated to the interior; +the hydration is in consequence more gradual, +and resistance being offered to the expansion of the +inner parts, a harder and denser material is obtained. +That this expansion contains an element of truth is +indicated by the practice of employing the granular +crystalline variety for the preparation of moulding +plaster. The explanation appears, however, to be inadequate +in several respects, especially in view of the +fact that plasters for moulding are reduced to a fine +state of division before use. It seems as if this treatment +must, in great part at any rate, break up the +crystalline aggregates.</p> + +<p>In order to discover a more satisfactory explanation, +let us examine the results of the chemical analysis of +plasters used in commerce. One is struck by the large +percentage of water they usually contain. Thus, four +samples of ordinary plaster analyzed by Landrin have +an average of 90.17 per cent. of CaSO4 and 7.5 per +cent. of water, while two samples of best plaster contained +89.8 per cent. of CaSO4 and 7.93 per cent. of +water. These numbers do not add up to 100, the difference +being due to silica and other impurities of the +original gypsum, amounting altogether to about 3 per +cent.</p> + +<p>It might be suggested that the reason why these +plasters set more slowly than completely dehydrated +plaster is owing simply to the fact that they contain, +apparently, some unaltered gypsum, which serves to +<i>dilute</i> the action. Were this so, a similar result, as far +as time of setting is concerned, should be obtained +with a plaster containing a corresponding quantity of +dead-burnt material. This, however, is not found to +be the case. The time of setting appears, then, to be +connected in some special and peculiar manner with +the retention of water by the burnt plaster.</p> + +<p>The following explanation of this connection is offered, +an explanation only tentative at present, owing to +want of experimental data.</p> + +<p>The following substances are known:</p> + +<blockquote> +<p>Gypsum, and set plaster, CaSO4 + 2 H<sub>2</sub> O, containing +20.93 per cent. of water.</p> + +<p>Plaster completely burned at moderate temperature, +CaSO4, probably amorphous.</p> + +<p>Anhydrite and dead-burned plaster, CaSO4, crystalline.</p> + +<p>Selenitic deposit from boilers, 2 CaSO4 + H<sub>2</sub> O, or +CaSO4 + 1/2 H<sub>2</sub> O, containing 6.2 per cent. of water. +</blockquote> + +<p>The circumstance that the hot calcium sulphate +can crystallize with 1/4 its normal amount of water indicates +that for this proportion of water it has a greater +attraction than for the other 3/4. Having a similar +bearing is the fact that when burned at lower temperatures, +gypsum only loses the last portions of water +with extreme slowness.</p> + +<p>Now, if it be the case that anhydrous calcium sulphate +has a greater attraction for the first half molecule +of water, then the operation of hydration will +proceed very rapidly at first, more slowly afterward. +Many such cases are known, <i>e.g.</i>, that of copper sulphate. +Conversely, if only 3/4 of the water of hydration +be expelled during the baking of gypsum, the material +obtained should hydrate itself more slowly. For our +present purpose it will be convenient to recalculate the +numbers given by Landrin (<i>vide supra</i>) so as to make +the calcium sulphate and water add up to 100. This +treatment of the numbers gives a mean result for the +six analyses of 7.68 per cent. of water, the amounts +not varying by more than 1 per cent.</p> + +<p>It will be seen that the dehydration has never passed +the composition corresponding to 2 CaSO4 + H<sub>2</sub>O; +indeed, the material approximates more nearly to the +composition 3 CaSO4 + H<sub>2</sub>O. It appears probable, +therefore, that in the successful preparation of plaster +the whole, or nearly the whole, of the gypsum is +changed, but that this change does not result in the +production of CaSO4, or of a mixture of CaSO4 and +CaSO4 + 2 H<sub>2</sub> O, but of a lower hydrate of calcium +sulphate.</p> + +<p>In the case of the analyses, given by Landrin, of fine +plaster for potteries, the percentages of water (8.14 and +8.08) correspond closely to that of a hydrate, 3 CaSO4 ++ 2 H<sub>2</sub>O, which would contain 8.1 per cent. of water.</p> + +<p>Some surprise may have been excited by the fact +that the well known method of revivifying hydrated +calcium sulphate has recently formed the subject of a +patent (Eng. pat., No. 15,406).</p> + +<p>The method described in the specification consists in +reducing the materials (waste moulds, etc.) to small +lumps, and baking between the temperatures of 95° +and 300°. It is mentioned that the whole of the water +must not be expelled. This is no doubt correct, but it +<a name="Page_12686" id="Page_12686"></a>must be effected by regulating the <i>time</i> of baking, since +by prolonging the operation all the water of crystallization +can be expelled far below 300°. To secure even +baking the mass is kept stirred by mechanical stirrers, +a necessary precaution, since the operation is to be +carried out in an ordinary kiln. The process is stopped +when a portion of the plaster is found to set in the +required time, a method of regulation which will probably +be found to work well in practice.—<i>Chem. Trade +Jour.</i></p> + +<hr /> + +<a name="ref11"></a><h2>SPACING THE FRETS ON A BANJO NECK.</h2> + +<h3>By Prof. C.W. MacCord.</h3> + +<p>The amateur performer on the banjo, if he be of a +mechanical turn, is often tempted to exercise his skill +by making an instrument for himself; and the temptation +is the greater because he can confine himself to +the essentials. The excellence of a banjo in respect to +power and tone depends mainly upon the rim and the +neck, that is, supposing the parchment head to be of +proper quality; but then the preparation of the heads +is a business of itself, and the amateur is no more expected +to make the head than to make the strings. So +again, all the minor accessories, such as pegs and tail +pieces, brackets and bridges, are kept in stock for his +benefit, and he may justly claim all the credit if his +efforts in connection with the two principal parts first +mentioned result in the production of a superior instrument. +Among these ready-made items is a "fret +wire" of peculiar section, furnished with a flange ready +for insertion into fine saw cuts across the neck, which +much facilitates his work.</p> + +<p>Of course, the correctness of the notes depends entirely +upon the accuracy with which the frets are spaced, +and the accompanying diagram exhibits a convenient +method of determining the spaces by graphic means.</p> + +<p class="ctr"><img src="./images/8-banjo.png" width="546" height="399" +alt="SPACING FOR BANJO FRETS."></p> +<p class="ctr">SPACING FOR BANJO FRETS.</p> + +<p>It is to be understood that when the distance from +the "nut," N, to the bridge, B, has been determined, +the first fret is to be placed at 1/18 of that distance from +the nut, the distance from the first to the second is to +be 1/18 of the remainder, and so on. To determine these +distances by computation, then, is a simple enough +arithmetical exercise; but it is exceedingly tedious, +since the denominators of the fractions involved increase +with great rapidity; being successive powers of +the comparatively large number 18, they soon become +enormous.</p> + +<p>In the large diagram, the distance, A C, on the horizontal +line corresponds to the distance, N B, on the +instrument. At A erect a vertical line, and mark upon +it a point B such that B C shall be exactly eighteen +times any convenient unit, B I. In the illustration B +C is 26 inches, and B I is 11/2 inches, so that B C is 27 +inches in length. About C as a center describe the +arcs, B L, I K, and through I draw a vertical line, cutting +B L in D; draw the radius D C, cutting the inner +arc, I K, in J, through J draw another vertical, cutting +B L in E, and so on.</p> + +<p>In the triangles, A B C, 1 D C, 2 E C, we have B I = +D J = E F = 1/18 of the hypotenuse in each case, therefore +the bases, A C, 1 C, 2 C, are divided in the same +proportion, as required, at the points 1, 2, 3. And we +might extend the arcs, B L, I K, and repeat the above + +operation until all the frets were located. But should +that be done, the diagram might become inconveniently +large, and some of the intersections might not be +reliably determined. In order to avoid this, the spacing +of the outer arc may be stopped at any convenient +division, as L. The vertical by which that point is determined +cuts B C at B', and through B' a new arc, B' +L', is described. Through the points in which this arc +cuts the radial lines already drawn, a new series of verticals +is passed, which will divide another portion of A +C as required, and by repeating this process the spacing +of the whole neck may be effected by a diagram of +reasonable size.</p> + +<hr /> + +<a name="ref17"></a><h2>GLOVE MAKING.</h2> + +<p>Glove making is almost a century old in this country, +having been begun in the neighborhood of Gloversville +and Johnstown, N.Y., about 1803. Until 1862 +the manufacture of gloves in Fulton County, although +even then the chief manufacturing industry, was of +comparatively small importance. Gloversville and +Johnstown were then quiet villages of from three to +four thousand people. The flourishing establishments +of to-day, or such of them as then existed, were small +and comparatively unimportant. In 1862 the stimulating +influence of a high protective tariff showed +itself in the increased business at Gloversville, Johnstown, +and the adjoining hamlet, Kingsboro. These +became at once the leading sources of supply for the +home market gloves of a medium grade. The quality +of the product has steadily improved, and the variety +has been increased, until now American-made gloves +are steadily driving out the foreign gloves. The skill +of American glovers is equal to that of foreign glove +makers, and in some respects—notably in the quality +of the stitching, and, in some grades, the shape—the +American gloves are the best. Foreign expert workmen +have been drawn over here from the great glove +centers of Europe, so that the greatest skill has been +secured here. The annual value of the glove industry +in Fulton County has reached about $7,000,000.</p> + +<p>One hundred and seventy-five glove makers and +20,000 people in Fulton County draw their subsistence +directly from glove making. Some of the firms have +a business reaching from $100,000 to $500,000 yearly. +The majority, however, have small shops, and do a +small but profitable business. Most of the work in +Fulton County, as abroad, is done at the homes of the +workers. The streets of Gloversville and Johnstown +are lined with pretty and tasteful homes, in which the +hum of the sewing machine is constantly heard during +the working hours of the day, but the workers are exceptionally +fortunate in being able while earning good +wages to enjoy all the comforts and surroundings of +home, and in being practically their own masters and +mistresses.</p> + +<p>Before the leather can be cut and sewed into the +handsome articles that are sold over the counters of +the retail dry goods houses and furnishing goods stores +as gloves, the skins from which they are made must be +specially prepared. The two important points in this +preparation are the removal of the albuminous portion +of the skin and the retention and chemical changing + +of the gelatinous part, so that it shall become pliable, +elastic, and resist decomposition.</p> + +<p>There are various methods which produce these results, +and they are technically known as tanning, +alum dressing, oil dressing, and Indian dressing. Each +method produces a leather distinctly different from +that produced by any other. All the preliminary processes +of these various methods are alike in principle, +although they vary somewhat in detail. The object +in all is to remove the hair from the hide, separate the +fleshy and albuminous matter, and leave only the gelatinous, +which alone is susceptible to the chemical action +and can be transformed by it into leather.</p> + +<p>When the skins are received in the factory they are +thoroughly soaked to open out the texture and prepare +them for the removal of the hair. Then the skins are +placed in vats of lime water, where, for two or three +weeks, the lime works into the flesh and albuminous +matter, and loosens the hair. The skins having thus +been properly softened, the dirty but picturesque operation +of beaming for removing the hair ensues. Before +each beamer, as the workman is called, is an inclined +semi-cylindrical slab of wood covered with zinc. +The skin is first spread upon this, and the broad, +curved beam of the knife glides across it from end to +end, scraping and removing all the loosened hair, the +scarf skin, and the small portion of animal matter adhering +to the skin.</p> + +<p>After the unhairing, kid skins must be fermented in +a drench of bran, whose purpose is to completely decompose +the remaining albuminous matter, and also to +remove all traces of the lime. The operation is extremely +delicate. While the gelatine is not so sensitive +to the decomposing action of the ferment, nevertheless +great care is required to prevent overfermentation +and resulting damage to the texture of the skin. +It is impossible for even the most experienced to tell +just how long the fermentation should continue. +Sometimes the work is done in two or three hours, +and sometimes it requires as many days. Incessant +watchfulness both day and night is required to detect +the critical moment. With the less delicate skins this +bran bath is not necessary. Lime and acid solutions +accomplish the same purpose. When the gelatine +matter is all removed the skins are ready for the actual +curative process.</p> + +<p>Oil dressing or Indian dressing—which merely differ +in application, but are founded upon the same principle—is +the most simple method of curing skins. The +principle of each is the soaking of the gelatine fibers +of the skin with oil, the union of the latter and the +gelatine appearing in the form of oxide, and resulting +in the insoluble, undecomposable, pliant, and tough +material known to the commercial world as leather. +The first step in the oil dressing, after the skins have +been duly soaked to render them porous and absorptive, +is to cover them with fish oil and place them in +the stocks or fulling machines—huge wooden hammers +with notched faces working in iron cases—where they +are beaten and turned, and subjected to a uniform +pressure until the oil is gradually absorbed. After +taking them out, hanging them up, and stretching +them, the oil and fulling process is repeated according +to the thickness of the skin, and until every part of it +<a name="Page_12687" id="Page_12687"></a>is full of oil. After this the skins are dried in a mild +heat that causes the oxidization of the oil. This being +completed, all the superfluous oil is removed by putting +the skins in an alkali bath. Then the curing process +is complete.</p> + +<p>With the preparation of kid leather alum is the +astringent curative agent. Its operation is accompanied +by that of others whose purpose is to secure +elasticity and pliability, and mainly to preserve that +beautiful texture which makes kid leather superior to +all others. These assistants in the process are eggs, +flour, and salt. They are combined into what is called +a custard. A proper quantity of the custard and a +number of skins having been put together in a dash +wheel, where they are thrown about for some time, the +open pores of the skin absorb the custard freely, and +become swelled by the chemical union of the custard +and the skin. In trade parlance this swelling is known +as "plumping." This having progressed satisfactorily, +the skins are folded together with the fleshy side outward, +and are dried by a gentle heat.</p> + +<p>They are now cured, but they are yet hard and +rough. Another objectionable feature is that they +are of unequal thickness. Breaking and staking, as +they are called, are now resorted to, to make the skins +soft, pliable, and of even texture, removing the superfluous +chemicals with which they become charged, and +the stiffness by manipulating the fibers. Much trained +skill and dexterity, especially in knee and arm staking, +are required in the stretching, which is the essential +feature of these operations. Breaking is first resorted +to. The break beam, which is armed at each end with +a knife edge, oscillates up and down. In a frame beneath +it the operator stretches the dried and stiff skin. +The break beam comes down upon the skin, stretches +and softens it, and removes much surplus custard. The +operator presents a new surface to each stroke of the +break beam, and in a very short space of time the entire +skin is rendered soft and pliable.</p> + +<p>Further manipulation upon the arm or knee stake—of +which a dull, semicircular knife blade, supported +upon a suitable standard upon the floor or upon a +beam about opposite the worker's elbow is the main +feature—is required. The skin must be drawn across +this knife blade with a considerable application of +force so as to reduce the unduly thick parts, stretch +the skin and secure a uniform thickness suitable for +gloves. Much dexterity, especially in the case of fine +skins, is required in this operation to avoid cutting or +tearing. The operator places the fleshy side of the +skin over the knife, grasps the two ends of the skin, +and placing his knee upon it and slowly drawing the +skin across the knife edge, he brings his weight to bear +upon it. If the operator is skilled and experienced the +skin yields quickly, when needed, to the strain applied +and a uniform texture is secured. The operation of +transforming the skin into leather is now finished, but +age is necessary to secure perfect pliability and softness. +The skins are, therefore, laid away to let the +slow chemical operation going on within them be +completed.</p> + +<p>The visitor can now watch the further processes of +manufacture by visiting the dye rooms. Skins which +have already been aged are immersed in dye vats, +where the delicate colors are imparted to them. The +same care is not required in obtaining the ordinary +range of dark colors, for these are "brushed" on, the +skin being spread upon a glass slab and the dye being +painted on with a brush. After they are dyed the +skins are sometimes somewhat hard, and in some classes +have to be staked again in order to restore their +pliability. The finishing touches to a kid skin are secured +by rubbing the grain side over with a size, which +imparts a gloss. The experience of Gloversville manufacturers +with "buck" gloves has enabled them to impart +a special finish to a skin which is very popular +under the title of "Mocha." This is the same as suede +finish, which is produced in other countries by shaving +off the grain side of the skin at an early stage of its +progress. The Gloversville method is much better, +however, and has more perfect results. Here the grain +is removed, and the velvet finish secured by buffing +the surface on an emery wheel. The surface of the +leather is cut away in minute particles by this process, +and the result is an exceedingly even and velvety texture, +superior to that obtained by other methods. +European manufacturers do not approach the Americans +in this respect.</p> + +<p>The leathermaker leaves off and the glovemaker +begins.</p> + +<p>A marble slab lies before the cutter on a table, and +every particle of dirt or other inequality is removed +before "doling." The skin is spread, flesh side up, +upon the slab, and the cutter goes over it with a broad +bladed chisel or knife, shaving down inequalities and +removing all the porous portions. The dexterity with +which this is done makes the operation appear extremely +simple, but any but a skilled and experienced +operative would almost surely cut through the skin. +The most delicate part of the glovemaker's art, in +which exact judgment is required, comes in preparing +the "tranks" or slips, from which the separate gloves +are cut. The trank must be so cut as to have just +enough leather to make a glove of a certain size and +number. The operation would be easy enough if the +material were hard and stiff, and if the elasticity were +uniform, but this is rarely the case.</p> + +<p>To accomplish this operation the trank must be +firmly stretched in one direction, and while so stretched +a "redell" stamps the proper dimensions in the other +direction, to which the leather is trimmed. Upon the +nicety with which this operation is performed depends +the question of whether the finished glove will stretch +evenly or too much or too little in one direction or +the other. After this the trank or outline of the glove +must be cut out. In olden times of glove manufacture +an outline was traced upon the leather and the pattern +was cut with shears. Modern invention has produced +dies and presses which are universally used. The steel +die has the outline of a double glove, including the +opening for the thumb piece. The die rests upon the +bed of the press. Several tranks are laid upon it, the +lever is drawn, and in a moment the blanks are cut out +clean and smooth. The gussets, facings, etc., are cut +from the waste leather in the thumb opening at the +same operation. Similar dies are used in the cutting +of the thumb pieces and fourchettes or strips forming +the sides of the fingers.</p> + +<p>The pieces now go to the great sewing rooms of the +factory, where are long rows of busy sewing girls. If + +the manufacturer of years ago could revisit the scenes +of his earthly toil, and wander through the sewing +rooms of a modern factory, he would doubtless be +greatly amazed at the sight presented there. In his +day such a thing was unknown. The glove was then +held in position by a hand clamp, while the sewing +girl pushed the needle in and out, making an overseam. +All this is done now in an infinitely more rapid +manner by machine, and with resulting seams that +are more regular and strong than those made by the +hand sewer. The overseam sewers earn large wages, +and their places are much coveted. Overlapping +seams are produced on the pique machine, which is a +most ingenious mechanism. The essential feature of +this machine is a long steel finger with a shuttle and +bobbin working within, and the finger of the glove is +drawn upon this steel finger, permitting the seam to +be sewn through and through. The visitor to the factory +can see also the minor operations of embroidering, +lining—in finished gloves—sewing the facing, sewing +the buttonholes, putting on the buttons, and trimming +with various kinds of thread. Before the gloves are +ready for the boxes one more operation remains. The +gloves are somewhat unsightly as they come from the +sewers' hands, and must be made trim and neat. To +secure these desirable results the gloves are taken to +the "laying-off" room.</p> + +<p>In this are long tables with a long row of brass hands +projecting at an acute angle. These are filled with +steam and are too hot to touch. These steam tables +by ingenious devices are so arranged that it is impossible +to burn the glove or stiffen the leather by too +much heat, a common defect in ordinary methods. The +operation of the "laying-off" room is finished with +surprising quickness. Before each table stands an +operator, who slips a glove over each frame, draws it +down to shape, and after a moment's exposure to the +warmth removes it, smooth, shapely, and ready for the +box. The frames upon which the gloves are drawn +are long and narrow for fine gloves and short and +stubby for common ones. Then the glove is taken to +the stock room, where there are endless shelves and +bins to testify to the chief drawback to glove making, +the necessity for innumerable patterns.—<i>The Mercer.</i></p> + +<hr /> + +<a name="ref15"></a><h2>FABRIC FOR UPHOLSTERY PURPOSES.</h2> + +<p>The object of this invention is to produce a firm, +solid, dust-resisting, and durable woven cloth, composed, +preferably, entirely of cotton, but it may be of a +cotton warp combined with a linen or other weft, and +is particularly applicable for covering the seats and +cushions of railway and other carriages, for upholstering +purposes, for bed ticking, and for various other +uses. To effect this object, a cotton warp and, preferably, +a cotton weft also are employed, or a linen, +worsted, or other weft may be used. Both the yarns +for warp and weft may be either dull or polished, according +to the appearance and finish of cloth desired. +The fabric is woven in a plain loom, and the ends are +drawn through say eight heald shafts, but four, +sixteen, or thirty-two heald shafts might be employed. +When eight heald shafts are employed, the warp is +drawn as follows: The 1st warp end in the first heald +shaft, the 2d warp end in the second heald shaft, and +so on, the remaining six warp ends being drawn +in, in consecutive order, through the remaining six +heald shafts; the 9th warp end is drawn in through +the first heald shaft, and so on, the drawing in of the +other ends being repeated as above. The order of the +shedding is as follows: 1st change. The 1st and 3d +heald shafts fall, the rest remaining up. 2d change. +The 5th and 7th shafts fall, and the 1st and 3d rise. +3d change. The 2d and 4th shafts fall, and the 5th +and 7th rise. 4th change. The 6th and 8th shafts fall, +and the 2d and 4th shafts rise. The result is that each +weft thread, a, passes under six warp threads, b, and +over two warp threads, in the manner illustrated by +the accompanying diagram. In drawing in, when four +heald shafts are employed, the 1st warp end is drawn +in through the 1st heald shaft, the 2d through the +2d shaft, the 3d through the 1st, the 4th through the 2d, +the 5th through the 3d, the 6th through the 4th, the +7th through the 3d, and 8th through the 4th shaft, and +repeating with the 9th end through the 1st shaft. In +shedding, the 1st heald shaft is lowered, then the 3d, +then the 2d, and then 4th. The result, in this case, is +still the same, viz., that each weft thread passes under +six warp ends and over two warp ends. Although a +cotton warp is spoken of in some cases, worsted or other +yarn can be added to the cotton warp to obtain a +variation in the pattern or design.—<i>Jour. of Fabrics.</i></p> + +<p class="ctr"><img src="./images/9-weave.png" width="400" height="407" +alt="Fabric Weave Illustration."></p> + + +<hr /> + +<a name="ref18"></a><h2>REVERSIBLE INGRAIN OR PRO-BRUSSELS CARPET.</h2> + +<p>The object of this invention is to manufacture, in a +cheap fabric, a closer imitation of Brussels carpets. As +is well known, an ordinary Brussels carpet is made +with a pattern on one side only, but according to this +invention, it is intended to produce a pattern on both +sides of the ingrain or pro-Brussels carpet, so that it +will be reversible. In manufacturing a reversible carpet +of this class according to the present invention, the +pattern is formed by means of the warp and weft combined, +and any suitable ingrain warp operated by the +harness or jacquard of the loom may be used. In combination +with ingrain warp, a fine catching or binding +warp, operated by the gear or jacquard harness of the + +loom, is employed, such fine catching warp being used +to bind the weft into the fabric, therefore, if the fabric +be woven two-ply, the ingrain warps are thrown on +both the under and upper surfaces of the fabric, as +well as in between the weft, according to the pattern +being woven, by which means four colors are shown on +both sides of the fabric, two being produced by the +weft, and two by the ingrain warps. More than four +colors, however, can be produced upon each side by +multiplying the number of colored wefts and warps +employed. If the fabric woven be a three-ply, with +the addition of the ingrain warps thrown on each face +of the fabric, then five or more colors would be imparted +to the carpet, as any number of colors can be +used to form a given pattern, by planting or arranging +the colors in the warp, and the remaining colors by the +wefts, and so on. The ingrain warp thread, therefore, +together with the weft, used as stated above, produces +an effective pattern on both sides of the carpet; +consequently, it becomes reversible, and this can be +accomplished whether the carpet woven be two, three, or +other number of ply. By reference to the accompanying +sheets of drawings, this invention will be better +understood. Fig. 1 is an enlarged cross section of an +improved carpet, a three-ply, that is to say, it is a carpet +wherein three shuttles are employed, each carrying +a differently colored weft; a represents the weft threads +which may be composed of any suitable fiber, b and c +are cotton or other fine warp threads, which are employed +for binding the weft together, while d and e +represent the ingrain or woolen warp, where it will be +seen that each ingrain warp, besides lying between +the weft, is thrown on both sides of the fabric, for the +purpose of forming figures thereon. It will, therefore, +be seen that a carpet made according to Fig. 1 will +show five colors—three colors produced by the weft +and two colors produced by the ingrain warp. Fig. 2 +represents a carpet made with two-ply, in which case +only four colors will be produced, two by the weft and +two by the ingrain warp. It is, consequently, obvious +that a carpet made in the manner above described will +have a corresponding pattern or figure on both its +sides, allowing it to be used on both sides. Fig. 3 also +shows a two-ply carpet, but, in this case, six colors are +produced, <i>i.e.</i>, two colors by the weft and four by the +ingrain warp, marked d, dı, e, and eı, the warp being +so manipulated by the harness as to make the carpet +reversible, and having a corresponding pattern or figure +on both sides.—<i>Journal of Fabrics.</i></p> + +<p class="ctr"><img src="./images/9-rolls.png" width="453" height="260" +alt="Thread Twist Illustration."></p> + + +<hr /> + +<a name="ref14"></a><h2>ARĈO-PICNOMETER.</h2> + +<p>A modified arĉometer has been recently patented +by Aug. Eichhorn, in Dresden, Germany (Deutsches +Reichs-Patent, No. 49,683), which will prove a great +boon to chemists, distillers, physicians, etc., as it +affords an easy means of determining the specific +gravity of liquids, especially such of which only small +quantities can be conveniently obtained.</p> + +<p>With the ordinary arĉometers, as hitherto constructed, +a considerable quantity of the test fluid is +required, and an elaborate calculation necessary for +each determination. In the new arĉo-picnometer +these drawbacks are ingeniously avoided, so that the +specific gravity of any liquid can be quickly and easily +obtained with astonishing accuracy.</p> + +<p>The new and important feature of this instrument consists +in a glass bulb, c—see accompanying sketch—which +is filled with the liquid whose gravity is to be +determined. Thus, instead of floating the entire apparatus +in the test fluid, only a very small quantity of +the latter is required, an advantage which can hardly +be overestimated, considering how difficult it is in +many instances to procure the necessary supply.</p> + + +<p class="ctr"><img src="./images/9-valve.png" width="281" height="395" +alt="Device Illustration."></p> + + +<p>The glass bulb, c, when filled with the test fluid, is +closed by means of an accurately fitting glass stopper, +d, and the instrument is then placed in a glass cylinder +filled with distilled water of 17.5 deg. temperature +(Centigrade). The gravity is then at once shown on the +divided scale in the tube, a. The lower bulb, f, contains +some mercury; e is a small glass knob, which +serves to maintain the balance, while b is an empty +glass bulb (floater).</p> + +<p>These instruments are admirably adapted for determining +the gravity of alcohol, petroleum, benzine, +and every kind of oil, also for testing beer, milk, vinegar, +grape juice, lye, glycerine, urine, etc.</p> + +<p>As the process is an exceedingly simple one and free +<a name="Page_12688" id="Page_12688"></a>from the drawbacks of the arĉometer, we are justified +in concluding that the arĉo-picnometer will soon be in +general use.</p> + +<p style="text-align: right;">H. HENSOLDT, Ph.D.</p> + +<p>Petrographical Laboratory, School of Mines, +Columbia College.</p> + +<hr /> + +<h3>[Continued from SUPPLEMENT, No. 793, page 12669.]</h3> + +<a name="ref16"></a><h2>GASEOUS ILLUMINANTS.<a name="FN16anchor_1"></a><a href="#FN16_1"><sup>1</sup></a></h2> + +<h3>By Prof. VIVIAN B LEWES.</h3> + +<h3>IV.</h3> + +<p>Mr. Frank Livesey, in the concluding sentence of +a paper read before the Southern District Association +of Gas Managers and Engineers during the past month, +on "A Ready Means of Enriching Coal Gas," speaking +of enrichment by gasolene by the Maxim-Clarke process, +said "it should, in many cases, take the place of +cannel, to be replaced in its turn, probably, by a water +gas carbureted to 20 or 25 candle power." And now, +having fully reviewed the methods either in use or +proposed for the enrichment of gas, we will pass on to +this, the probable cannel of the future.</p> + +<p>Discovered by Fontana, in 1780, and first worked by +Ibbetson, in England, in 1824, water gas has added a +voluminous chapter to the patent records of England, +France, and America, no less than sixty patents being +taken out between 1824 and 1858, in which the action +of steam on incandescent carbon was the basis for the +production of an inflammable gas.</p> + +<p>Up to the latter date the attempts to make and utilize +water gas all met with failure; but about this time +the subject began to be taken up in America, and the +principle of the regenerator, enunciated by Siemens +in 1856, having been pressed into service in the +water-gas generator under the name of fixing chambers or +superheaters, we find water gas gradually approaching +the successful development to which it has attained in +the United States during the last ten years. Having +now, by the aid of American skill, been brought into +practical form, it is once more attempting to gain a +foothold in Western Europe—the land of its birth.</p> + +<p>When carbon is acted upon at high temperatures by +steam, the first action which takes place is the decomposition +of the water vapor, the hydrogen being liberated, +while the oxygen unites with the carbon to +form carbon dioxide:</p> + + +<table align="center" summary=""> +<tr><td> Carbon.</td><td> Water.</td></tr> +<tr><td> C<sub> </sub> + </td><td>2H<sub>2</sub>O = CO<sub>2</sub> + 4H<sub>2</sub></td></tr> +</table> + +<p>And the carbon dioxide so produced interacts with +more red-hot carbon, forming the lower oxide—carbon +monoxide:</p> + +<p class="ctr">CO<sub>2</sub> + C<sub> </sub> = 2CO<sub> </sub></p> + +<p>So that the completed reaction may be looked upon as +yielding a mixture of equal volumes of hydrogen and +carbon monoxide, both of them inflammable but non-luminous +flames. This decomposition, however, is rarely +completed, and a certain proportion of carbon dioxide +is invariably to be found in the water gas, which, in +practice, generally consists of a mixture of about this +composition:</p> + +<table align="center" cellspacing=3 summary="Water Gas"> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><th colspan="2"> WATER GAS.</th></tr> +<tr><td>Hydrogen</td><td>48.31</td></tr> +<tr><td>Carbon monoxide</td><td>35.93</td></tr> +<tr><td>Carbon dioxide</td><td>4.25</td></tr> +<tr><td>Nitrogen</td><td>8.75</td></tr> +<tr><td> Methane</td><td>1.05</td></tr> +<tr><td> Sulphureted hydrogen</td><td> 1.20</td></tr> +<tr><td>Oxygen</td><td>0.51</td></tr> +<tr><td> </td><td>———</td></tr> +<tr><td> </td><td> 100.00</td></tr> +</table> + +<p>The above is an analysis of water gas made from ordinary gas coke +in a Van Steenbergh generator.</p> + +<p>The ratio of carbon monoxide and carbon dioxide present entirely +depends upon the temperature of the generator, and the kind of +carbonaceous matter employed. With a hard, dense anthracite coal, for +instance, it is quite possible to attain a temperature at which there +is practically no carbon dioxide produced, while with an ordinary form +of generator and a loose fuel like coke, a large proportion of carbon +dioxide is generally to be found.</p> + +<p>The sulphureted hydrogen in the analysis quoted is, of course, due +to the high amount of sulphur to be found in the gas coke, and is +practically absent from water gas made with anthracite, while the +nitrogen is due to the method of manufacture, the coke being, in the +first instance, raised to incandescence by an air blast, which leaves +the generator and pipes full of a mixture of nitrogen and carbon +monoxide (producer gas), which is carried over by the first portions +of water gas into the holder. The water gas so made has no photometric +value, its constituents being perfectly non-luminous, and attempts to +use it as an illuminant have all taken the form of incandescent +burners, in which thin mantles or combs of highly refractory metallic +oxides have been heated to incandescence. In carbureted water gas this +gas is only used as the carrier of illuminating hydrocarbon gases, +made by decomposing various grades of hydrocarbon oils into permanent +gases by heat.</p> + +<p>Many forms of generator have been used in the United States for the +production of water gas, which, after or during manufacture, is mixed +with the vapors and permanent gases obtained by cracking various +grades of paraffin oil, and "fixing" them by subjecting them to a high +temperature; and in considering the subject of enrichment of coal gas +by carbureted water gas, I shall be forced, by the limited time at my +disposal, to confine myself to the most successful of these processes, +or those which are already undergoing trial in this country.</p> + +<p>In considering these methods, we find they can be divided into two +classes:</p> + +<p>1. Continuous processes, in which the heat necessary +to bring about the interaction of the carbon and steam +is obtained by performing the operation in retorts +externally heated in a furnace; and</p> + +<p>2. Intermittent processes, in which carbon is first +heated to incandescence by an air blast, and then, the +air blast being cut off, superheated steam is blown in +until the temperature is reduced to a point at which +the carbon begins to fail in its action, when the air is +again admitted to bring the fuel up to the required +temperature, the process consisting of alternate formation + +of producer gas with rise of temperature, and of +water gas with lowering of the temperature.</p> + +<p>Of the first class of generator, none, as far as I know, +have as yet been practically successful, the nearest approach +to this system being the "Meeze," in which +fire clay retorts in an ordinary setting are employed. +In the center of each retort is a pipe leading nearly to +the rear end of the retort, and containing baffle plates. +Through this a jet of superheated steam and hydrocarbon +vapor is injected, and the mixture passes the +length of the inner tube, and then back through the +retort itself—which is also fitted with baffle plates—to +the front of the retort, whence the fixed gases escape by +the stand pipe to the hydraulic main, and the rich gas +thus formed is used either to enrich coal gas or is +mixed with water gas made in a separate generator. +In some forms the water gas is passed with the oil +through the retort. In such a process, the complete +breaking down of some of the heavy hydrocarbons +takes place, and the superheated steam, acting on the +carbon so liberated, forms water gas which bears the +lower hydrocarbons formed with it; but inasmuch as +oil is not an economical source of carbon for the production +of water gas, this would probably make the +cost of production higher than necessary. This system +has been extensively tried, and indeed used to a certain +extent, but the results have not been altogether +satisfactory, one of the troubles which have had to be +contended with being choking of the retorts.</p> + +<p>Of the intermittent processes, the one most in use in +America is the "Lowe," in which the coke or anthracite +is heated to incandescence in a generator lined +with firebrick, by an air blast, the heated products of +combustion as they leave the generator and enter the +superheaters being supplied with more air, which +causes the combustion of the carbon monoxide present +in the producer gas, and heats up the firebrick "baffles" +with which the superheater is filled. When the necessary +temperature of fuel and superheater has been +reached, the air blasts are cut off, and steam is blown +through the generator, forming water gas, which +meets the enriching oil at the top of the first superheater, +called the 'carbureter,' and carries the vapors +with it through the main superheater, where the +"fixing" of the hydrocarbons takes place.</p> + +<p>The chief advantage of this apparatus is that the +enormous superheating space enables a lower temperature +to be used for the "fixing." This does away, +to a certain extent, with the too great breaking down +of the hydrocarbons, and consequent deposition of +carbon. This form of apparatus has just found its +way to this country, and I describe it as being the one +most used in the States, and the type upon which, +practically, all water gas plant with superheaters has +been founded.</p> + +<p>The Springer apparatus, which is under trial by one +of the large gas companies, differs from the Lowe +merely in construction. In this apparatus the superheater +is directly above the generator; and there is +only one superheating chamber instead of two. The +air blast is admitted at the bottom, and the producer +gases heat the superheater in the usual way, and when +the required temperature is reached, the steam is +blown in at the top of the generator, and is made to +pass through the incandescent fuel, the water gas being +led from the bottom of the apparatus to the top, +where it enters at the summit of the superheater, +meets the oil, and passes down with it through the +chamber, the finished gas escaping at the middle of +the apparatus.</p> + +<p>This same idea of making the air blast pass up +through the fuel, while in the subsequent operation +the steam passes down, is also to be found in the +Loomis plant, and is a distinct advantage, as the fuel +is at its hottest where the blast has entered, and, in +order to keep down the percentage of carbon dioxide, +it is important that the fuel through which the water +gas last passes should be as hot as possible, to insure +its reduction to carbon monoxide.</p> + +<p>The Flannery apparatus is again but a slight modification +of the Lowe plant, the chief difference being +that, as the gas leaves the generator, the oil is fed into +it, and, with the gas, passes through a <img src="./images/d.png" alt="D" />-shaped retort +tube, which is arranged round three sides of the +top of the generator; and in this the oil is volatilized, +and passes, with the gas, to the bottom of the superheater, +in which the vapors are converted into permanent +gases.</p> + +<p>The Van Steenbergh plant, with which I have been +experimenting for some time, stands apart from all +other forms of carbureted water gas plant, in that the +upper layer of the fuel itself forms the superheater, +and that no second part of any kind is needed for the +fixation of the hydrocarbons, an arrangement which +reduces the apparatus to the simplest form, and leaves +no part which can choke or get out of order, an advantage +which will not be underrated by any one who +has had experience of these plants. While, however, +this enormous advantage is gained, there is also the +drawback that the apparatus is not fitted for use with +crude oils of heavy specific gravity, such as can be +dealt with in the big external superheaters of the +Lowe class of water gas plant, but the lighter grades +of oil must be used in it for carbureting purposes.</p> + +<p>I am not sure in my own mind that this, which appears +at first a disadvantage, is altogether one, as, in +the first place, the lighter grades of oil, if judged by +the amount of carbureting power which they have, +are cheaper per candle power, added to the gas, than +the crude oils, while their use entirely does away with +the formation of pitch and carbon in the pipes and +purifying apparatus—a factor of the greatest importance +to the gas manufacturer.</p> + +<p>The fact that light oils give a higher carburation +per gallon than heavy crude oil is due to the fact that +the latter have to be heated to a higher temperature +to convert them into permanent gas, and this causes +an over-cracking of the most valuable illuminating +constituents; and this trouble cannot be avoided, as, +if a lower temperature is employed, easily condensible +vapors are the result, which, by their condensation in +the pipes, give rise to much trouble.</p> + +<p>The simplicity of the apparatus is a factor which +causes a great saving of time and expense, as it reduces +to a minimum the risk of stoppages for repairs, +while the initial cost of the apparatus is, of course, +low, and the expense of keeping in order practically +<i>nil</i>.</p> + +<p>When I first made the acquaintance of this form of +plant, a few years ago, the promoters were confident + +that nothing could be used in it but American anthracite, +of the kind they had been in the habit of using +in America, and a light naphtha of about 0.689 specific +gravity, known commercially as 76 deg Baume.</p> + +<p>A few weeks' work with the apparatus, however, +quickly showed that, with a slightly increased blow, +and a rather higher column of fuel, gas coke could be +used just as well as anthracite, and that by increasing +the column of fuel, a lower grade of oil could be employed; +so that during a considerable portion of the +experimental work nothing but gas coke from the +Horseferry Road Works and a petroleum of a specific +gravity of about 0.709 were employed.</p> + +<p>Having had control of the apparatus for several +months, and, with the aid of a reliable assistant, having +checked everything that went in and came out of +the generator, I am in a position to state authoritatively +that, using ordinary gas coke and a petroleum of +specific gravity ranging from 0.689 to 0.709, 1,000 cubic +feet of gas, having an illuminating power of twenty-two +candles, can be made with an expenditure of 28 to +32 lb. of coke and 21/2 gallons of petroleum. The most +important factors, <i>i.e.</i>, the quantity of petroleum and +the illuminating value of the gas, have also been +checked and corroborated by Mr. Heisch and Mr. Leicester +Greville.</p> + + +<table align="center" cellspacing="5" cellpadding="5" summary="Water Gas"> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><td align="center" colspan="2">Total gas made = 8,700 cubic feet.</td></tr> +<tr><td>Time taken: Blowing.</td><td>1 hour.</td></tr> +<tr><td>Time taken: Making.</td><td>50 minutes.</td></tr> +<tr><td>Fuel used: Gas coke.</td><td>270 lb. = 31 lb. per 1,000 c.f.</td></tr> +<tr><td>Fuel used: Naphtha, sp. gr. 0.709.</td><td>34 gals. = 2.7 gals. per 1,000 c.f.</td></tr> +<tr><td align="center" colspan="2">Illuminating power of gas = 21.9 candles.</td></tr> +</table> + +<p>I must admit that these results far exceeded my expectations, +although they only confirmed the figures +claimed by the patentee; and there are not wanting +indications that, when worked on a large scale and +continuously, they might be even still further lowered, +as it is impossible to obtain the most economical results +when making less than 10,000 cubic feet of the +gas, as the proper temperature of the walls of the +generator are not obtained until after several makes; +and it is only after about 8,000 cubic feet of gas has +been made that the best conditions are fulfilled.</p> + +<p>It will enable a sounder judgment to be formed of +the working of the process if the complete experimental +figures for a make of gas be taken.</p> + +<table align="center" cellspacing=3 summary="Water Gas"> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><th colspan="2">COMPOSITION OF THE GAS.</th></tr> +<tr><td>Hydrogen.</td><td>46.75</td></tr> +<tr><td>Olefines.</td><td>7.59</td></tr> +<tr><td>Ethane.</td><td> 6.82</td></tr> +<tr><td>Methane.</td><td>11.27</td></tr> +<tr><td>Carbon monoxide.</td><td>11.65</td></tr> +<tr><td>Carbon dioxide.</td><td>0.50</td></tr> +<tr><td>Oxygen.</td><td>0.17</td></tr> +<tr><td>Nitrogen. </td><td>8.25</td></tr> +<tr><td> </td><td>———</td></tr> +<tr><td> </td><td>100.00</td></tr> +</table> +<br /> +<table align="center" cellspacing=3 summary="Unpurified Gas"> +<colgroup><col align="left"><col align="right"></colgroup> +<tr><th colspan="2">UNPURIFIED GAS CONTAINED</th></tr> +<tr><td>Carbon dioxide.</td><td>2.32 per cent.</td></tr> +<tr><td>Sulphureted hydrogen.</td><td>2.84 per cent.</td></tr> +<tr><td>Total sulphur per 100 cu. ft.</td><td>= 6.67 per cent</td></tr> +<tr><td>Ammonia. </td><td> nil</td></tr> +<tr><td>Bisulphide of carbon. </td><td> nil</td></tr> +</table> +<br /> +<table align="center" cellspacing=3 summary="Unpurified Gas"> +<colgroup><col align="left"><col span="3" align="right"></colgroup> +<tr><td> </td><td>Gas produced </td><td>Naphtha used</td></tr> +<tr><td colspan="2"> </td><td>Gals.</td><td> Pts.</td></tr> +<tr><td>1st. Make. </td><td> 3,600 cu. ft.</td><td> 10</td><td> 7</td></tr> +<tr><td>2d. Make. </td><td> 2,800 cu. ft.</td><td> 7 </td><td> 6</td></tr> +<tr><td>3d. Make. </td><td> 2,300 cu. ft. </td><td> 5</td><td> 3</td></tr> +<tr><td> </td><td>——</td><td>—</td><td>—</td></tr> +<tr><td> </td><td> 8,700 </td><td> 24 </td><td> 0</td></tr> +</table> + + +<p>The last portion of the table shows the economy +which arises as the whole apparatus gets properly +heated. Thus the first make used 3 gallons naphtha +per 1,000 cubic feet, the second 2 gallons 6 pints per +1,000 cubic feet, and the third 2 gallons 4 pints per +1,000 cubic feet, and it is, therefore, not unreasonable +to suppose that in a continuous make these figures +could be kept up, if not actually reduced still lower.</p> + +<p>In introducing the oil it is not injected, but is simply +allowed to flow in by gravity, at a point about half +way up the column of fuel, the taps for its admission +being placed at intervals around the circumference of +the generator, and oil at first begins to flow down the +inside wall of the generator, but being vaporized by +the heat, the vapor is borne up by the rush of steam +and water gas, and is cracked to a permanent gas in the +upper layer of fuel. This I think is the secret of not +being able to use heavier grades of oil, these being sufficiently +non-volatile to trickle down the side into the +fire box at the bottom, and so to escape volatilization. +I have tried to steam-inject the oil, but have not found +that it yields any better results.</p> + +<p>One of the first things that strikes any one on seeing +a make of gas by this system is the enormous rapidity +of generation. Mr. Leicester Greville, who is chemist to +the Commercial Gas Company, in reporting on the +process, says, "The make of gas was at the rate of +about 86,000 cubic feet in 24 hours. A remarkable result, +taking into consideration the size of the apparatus." +It is quite possible, with the small apparatus, to +make 100,000 cubic feet in 24 hours; indeed the run for +which the figures are given are over this estimate; +and it must be borne in mind that this rapidity of +make gives the gas manager complete control over any +such sudden strains as result from fog or other unexpected +demands on the gas-producing power of his +works; while a still more important point is that +it does away with the necessity of keeping an enormous +bulk of gas ready to meet any such emergency, and +so renders unnecessary the enormous gasholders, which +add so much to the expense of a works, and take up so +much room.</p> + +<p>Perhaps the greatest objection to water gas in the public mind is +the dread of its poisonous properties, due to the carbon monoxide +which it contains; but if we come to consider the evidence before us +on the increase of accidents due to this cause, we are struck by the +poor case which the opponents of water gas are able to make out. No +one can for a moment doubt the fact that carbon monoxide is one of the +deadliest of poisons. It acts by diffusing through the air cells of +the lungs, and forming, with the coloring matter of the blood +corpuscles, a definite compound, which prevents them carrying on their +normal function of taking up oxygen and distributing it throughout the +body, to carry on that marvelous process of slow combustion which not +only gives warmth to the body, but also removes the waste tissue used +up by every action, be it +<a name="Page_12689" id="Page_12689"></a>voluntary or involuntary, and by hindering this, it at once stops +life.</p> + +<p>All researches on this subject point to the fact that something +under one per cent. only of carbon monoxide in air renders it fatal to +animal life, and this at first seems an insuperable objection to the +use of water gas, and has, indeed, influenced the authorities in +several towns, notably Paris, to forbid its introduction for domestic +consumption. Let us, however, carefully examine the subject, and see, +by the aid of actual figures, what the risk amounts to compared with +the risks of ordinary coal gas.</p> + +<p>Many experiments have been made with the view of determining the +percentage of carbon monoxide in air which is fatal to human or, +rather, animal life, and the most reliable as well as the latest +results are those obtained by Dr. Stevenson, of Guy's Hospital, in +consequence of the two deaths which took place at the Leeds forge from +inhaling uncarbureted water gas containing 40 per cent. of carbon +monoxide. He found that one per cent. visibly affected a mouse in one +and a half minutes, and in one hour and three quarters killed it, +while one-tenth of a per cent. was highly injurious. Let us, for the +sake of argument, take this last figure 0.1 per cent. as being a fatal +quantity, so as to be well within the mark.</p> + +<p>In ordinary carbureted water gas as supplied by the superheater +processes, such as the Lowe, Springer, etc., the usual percentage of +carbon monoxide is 26 per cent., but in the Van Steenbergh gas—for +certain chemical reasons to be discussed later on—it is generally +about 18 per cent., and rarely rises to 20 per cent. An ordinary +bedroom will be say 12 ft. X 15 ft. X 10 ft., and will therefore +contain 1,800 cubic feet of air, and such a room would be lighted by a +single bats-wing burner consuming not more than four cubic feet of gas +per hour. Suppose now the inmate of that room retires to bed in such a +condition of mental aberration that he prefers to blow out the gas +rather than take the ordinary course of turning it off—a process, by +the way, of putting out gas which is decidedly easier in theory than +in practice, especially in his presumed mental condition—you would +have in one hour the 1,800 cubic feet of gas in the room mixed with +four fifths of a cubic foot of carbon monoxide—the carbureted water +gas being supposed to contain 20 per cent.—or 0.04 per cent. In such +a room, however, if the doors and windows were absolutely air tight, +and there was no fireplace, diffusion through the walls would change +the entire air once an hour, so that the percentage would not rise +above 0.04; while in any ordinary room imperfect workmanship and an +open chimney would change it four times in the hour, reducing the +percentage to 0.01, a quantity which the most inveterate enemy of +water gas could not claim would do more than produce a bad headache, +an ailment quite as likely to have been caused by the same factor that +brought about the blowing out of the gas.</p> + +<p>Moreover, we are now talking about the use of carbureted water gas +as an enricher of coal gas, and not as an illuminant to be consumed +<i>per se.</i> and we may calculate that it would be probably used to +enrich a 16-candle coal gas up to 17.5 candle power. To do this 25 per +cent. of 22 candle power carbureted water gas would have to be mixed +with it, and taking the percentage of carbon monoxide in London gas at +5 per cent.—a very fair average figure—and 18 per cent. as the +amount present in the Van Steenbergh gas, we have 8.25 per cent. of +carbon monoxide in the gas as sent out—a percentage hardly exceeding +that which is found in the rich cannel gas supplied to such towns as +Glasgow, where I am not aware of an unusual number of deaths occurring +from carbon monoxide poisoning.</p> + +<p>The carbureted water gas has a smell every bit as strong as coal +gas, and a leak would be detected with equal facility by the nose; and +I think you will agree with me that the cry raised against the use of +carbureted water gas, for this reason, is one of the same character +that hampered the introduction of coal gas itself at the commencement +of this century.</p> + +<p>We must now turn to the chemical actions which are taking place in +the generator of the water gas plant, and these are more complex in +the case of the Van Steenbergh plant than in those of the Lowe type, +and, for that reason, yield a gas of more satisfactory +composition.</p> + +<p>Taking gas as made by the Lowe or Springer process, and contrasting +it with the Van Steenbergh gas, we are at once struck by several +marked differences.</p> + +<p>In the first place the hydrogen is far higher and the marsh gas or +methane lower in the Van Steenbergh than in the Lowe process, this +being due to the sharper cracking that takes place in the short column +of cherry red coke, as compared with the lower temperature employed +for a longer space of time in the Lowe superheater. Next we notice a +difference of 10 per cent. in the carbon monoxide, which is greatly +reduced in the Steenbergh generator by the carbon monoxide and marsh +gas reacting on each other as they pass over the red hot surface of +coke with formation of acetylene, which adds to the illuminants, this +action also reducing the quantity of marsh gas present.</p> + +<table align="center" cellspacing=3 cellpadding=2 summary="Lowe/Van Steen Gas"> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><th> </th><th> Lowe gas.</th><th align="center"> Van Steenbergh gas.</th></tr> +<tr><td> Hydrogen</td><td> 27.14</td><td> 46.75</td></tr> +<tr><td> Marsh gas</td><td> 25.35 </td><td> 11.27</td></tr> +<tr><td> Carbon monoxide</td><td> 26.84 </td><td> 18.65</td></tr> +<tr><td> Illuminants.</td><td>14.63 </td><td> 7.59</td></tr> +<tr><td> Ethane</td><td> — </td><td> 6.82</td></tr> +<tr><td> Carbon dioxide</td><td> 3.02 </td><td>0.50</td></tr> +<tr><td> Oxygen</td><td> 0.15</td><td> 0.17</td></tr> +<tr><td> Nitrogen.</td><td> 2.87</td><td>8.25</td></tr> +<tr><td> </td><td>——</td><td>——</td></tr> +<tr><td> </td><td>100.00</td><td>100.00</td></tr> +</table> + +<p>In the illuminants, if we add the higher members of the methane +series present to the olefines, we see they are about equal in each +gas, while the low percentage of nitrogen in the Lowe gas is due to +more careful working, and could easily be attained with the Van +Steenbergh plant by allowing the first portion of water gas to wash +out the producer gas before the hopper on top is closed.</p> + +<p>The cracking of the naphtha by the red hot coke is undoubtedly a +great advantage, for, as I have pointed out, the cracking of rushing +petroleum is an exothermic reaction, so that the coke at the top of +the generator gets hotter and hotter, and it is no unusual thing to +see the coke at the beginning of the make cherry red + +at the bottom and dull red at the top, while at the end of the make it +is almost black at the bottom and cherry red at the top, in this way +attaining the same advantage in working that the Springer and Loomis +do by their down blast, that is, having the fuel at its hottest where +the gas finally leaves it, so as to reduce the quantity of carbon +dioxide, and so lessen the expense of purification.</p> + +<p>It will be well now to turn for a few moments to the gas obtained +by cracking the light petroleum oils by themselves. The Russian and +American petroleum differ so widely in composition that it was +necessary to see in what way the gases obtained from them differed; +and to do this, equal quantities of American naphtha and a Russian +naphtha were cracked, by passing through an iron tube filled with +coke, and in each case heated to a cherry red heat, the gases being +measured, and then analyzed, with the following results:</p> + +<table align="center" cellspacing=3 cellpadding=2 summary=""> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><th> </th><th> American.</th><th> Russian.</th></tr> +<tr><td>No. of cubic feet per gallon.</td><td>72</td><td>104</td></tr> +<tr><td></td><td>——</td><td>——</td></tr> +<tr><td>Hydrogen</td><td> 26.0</td><td>45.3</td></tr> +<tr><td>Methane</td><td> 41.6</td><td>22.3</td></tr> +<tr><td>Ethane</td><td> 12.5</td><td>13.9</td></tr> +<tr><td>Olefines</td><td> 14.1</td><td>11.6</td></tr> +<tr><td>Carbon monoxide</td><td> 3.3</td><td>3.5</td></tr> +<tr><td>Carbon dioxide</td><td> 1.7</td><td>2.3</td></tr> +<tr><td>Oxygen</td><td> 0.8</td><td>1.1</td></tr> +<tr><td>Nitrogen</td><td> Nil.</td><td>Nil.</td></tr> +<tr><td></td><td>——</td><td>——</td></tr> +<tr><td></td><td>100.0</td><td>l00.0</td></tr> +</table> + +<p>Showing that, if the Russian oil is a little lower in +illuminants, it quite makes up by extra volume, but it +seemed to me to deposit a much larger proportion of +carbon.</p> + +<p>Taking 21/2 gallons of American naphtha, it would +give roughly 180 cubic feet of gas of the above composition, +while the remaining gas would be the ordinary +water gas. Taking the analysis of this as given, and +calculating from it what would be the composition of a +mixture of it with the naphtha gas, we obtain:</p> + +<table align="center" cellspacing=3 cellpadding=2 summary=""> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><th> </th><th> Calculated.</th><th>Actual.</th></tr> +<tr><td>Hydrogen</td><td> 47.09</td><td>42.09</td></tr> +<tr><td>Methane</td><td> 5.48</td><td>11.27</td></tr> +<tr><td>Olefines</td><td> 2.53</td><td>7.59</td></tr> +<tr><td>Ethane</td><td> 2.17</td><td>6.32</td></tr> +<tr><td>Carbon monoxide</td><td> 30.07</td><td>18.65</td></tr> +<tr><td>Carbon dioxide</td><td> 3.78</td><td>2.32</td></tr> +<tr><td>Oxygen</td><td> 0.56</td><td>0.17</td></tr> +<tr><td>Nitrogen</td><td> 7.17</td><td>8.25</td></tr> +<tr><td>Sulphureted hydrogen</td><td> 1.15</td><td>2.84</td></tr> +<tr><td></td><td>——</td><td>——</td></tr> +<tr><td></td><td>100.00</td><td>100.00</td></tr> +</table> + +<p>Showing how great the effect is of the diluents in the +water gas in preventing the overcracking of the hydrocarbons, +as shown by the increase in the percentage of +them present in the finished gas; while the enormous +reduction in the amount of carbon monoxide present is +due to the interaction between it and the paraffin hydrocarbons +in the presence of red-hot carbon, a point +which makes the Van Steenbergh apparatus enormously +superior to any of the superheater forms of plant.</p> + +<p>After all said and done, however, the reactions taking +place, although they have an intense fascination for +the chemist, are not the factors which the gas manager +deems the most important, the cost of any given process +being the test by which it must stand or fall; and +it will be well now to consider, as far as it is possible, +the expense of enriching coal gas by the various methods +I have brought before you.</p> + +<p>In order to be well above the prescribed limit of illuminating +power at all parts of an extended service, the +gas at the works must be sent out at an illuminating +power of 17.5 candles and we may, I think, fairly take +it that 16 candle coal gas, as made by the big London +companies, costs, as nearly as can be, 1s. per 1,000 cubic +feet in the holder, and the question we have now to +solve is the cost of enriching it from 16 to 17.5 candle +power. When this is done by cannel, the cost is 2.6 +pence per candle power, so that the extra 11/2 would +cost 4d. per 1,000.</p> + +<p>Carbureting by the vapors of gasoline by the Maxim-Clarke +process costs 13/4d. per 1,000, so that the extra +candle power would mean an expenditure of 2.62d. +Unfortunately I have no figures upon which to calculate +the cost of producing such a gas by the Dinsmore +process, but with the three important water gas enrichers +we can deal.</p> + +<p>Using Russian fuel oil, which can be obtained in bulk +in London at 3d. per gallon, the proprietors of the +Springer plant guarantee 51/2 candle power per 1,000 +cubic feet of gas per gallon used, so that, to produce a +22 candle gas, 4 gallons would be used. The cost per +1,000 cubic feet may be roughly tabulated, as the coke +used amounts to about 40 lb.</p> + +<table align="center" cellspacing=3 cellpadding=2 summary=""> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td></td><td>s.</td><td>d.</td></tr> +<tr><td>Oil</td><td> 1</td><td>0</td></tr> +<tr><td>Coke</td><td> 0</td><td>3</td></tr> +<tr><td>Labor and purification</td><td> 0</td><td>2</td></tr> +<tr><td>Charge on plant</td><td> 0</td><td>1</td></tr> +<tr><td></td><td colspan="2">——————</td></tr> +<tr><td></td><td>1</td><td>6</td></tr> +</table> + +<p>Twenty five per cent. of 12-candle gas when mixed +with 75 per cent. of the 16-candle gas gives the required +17.5 candle gas, which would therefore cost 1s. 11/2d., +or the enrichment would have cost 11/2d.</p> + +<p>By the Lowe process, an increase of 5.3-candle power +is guaranteed for the consumption of a gallon of the +same oil, so that the cost would be a shade higher, all +other factors remaining the same, while with the Van +Steenbergh process both grade of oil and consumption +of fuel vary from either of these processes. In order to +obtain a thousand cubic feet of 22-candle gas, two and +a half gallons of the lighter grade oil would be consumed, +and I am informed that there is now no difficulty +in obtaining oil of the right grade in London in +bulk at 4d. per gallon, which would make the cost:</p> + +<table align="center" cellspacing="3" cellpadding="2" summary=""> +<colgroup><col align="left"><col span="2" align="right"></colgroup> +<tr><td></td><td>s.</td><td>d.</td></tr> +<tr><td>Two and a half gallons of oil</td><td> 0</td><td>10</td></tr> +<tr><td>Thirty pounds of coke</td><td> 0</td><td>21/4</td></tr> +<tr><td>Labor and purification</td><td> 0</td><td>2</td></tr> +<tr><td>Charge on plant</td><td> 0</td><td>03/4</td></tr> +<tr><td></td><td colspan="2">——————</td></tr> +<tr><td></td><td>1</td><td>3</td></tr> +</table> + + +<p>And the enriched coal gas would, therefore, cost 1s. 3/4d. +per thousand, the extra 11/2-candle power having +been gained at an expense of 3/4d. or 1/2d. per candle.</p> + +<p>Tabulating these results we have—Cost of enriching +a 16-candle gas up to 17.5 candle power per 1,000 cubic +feet by cannel coal, 4d.; by Maxim-Clarke process, +2-6/10d.; by Lowe or Springer water gas, 11/2d.; by Van +Steenbergh water gas, 3/4d.</p> + +<p>In reviewing this important subject, and bringing a +wide range of experimental work to bear upon it, I +have, as far as is possible, divested my mind of bias +toward any particular process, and I can honestly +claim that the fact of the Van Steenbergh process showing +such great superiority is due to the force of carefully +obtained experimental figures, corroborated by +an experienced and widely known gas chemist, and by +the chief gas examiner of the city.</p> + +<p>In adopting any new method, the mind of the gas +manager must to a great extent be influenced by the +circumstances of the times, and the enormous importance +of the labor question is a main factor at the present +moment; with masters and men living in a strained +condition which may at any moment break into +open warfare, the adoption of such water gas processes +would relieve the manager of a burden which is growing +almost too heavy to be borne.</p> + +<p>Combining, as such processes do, the maximum rate +of production with the minimum amount of labor, they +practically solve the labor question. Requiring only +one-tenth the number of retort house hands that are +at present employed, the carbureted water gas can be +used for enrichment until troubles arise, and then the +gas can be used pure and simple, with a hardly perceptible +increase in expense, while the rapidity of make will +also give the gas manager an important ally in the +hour of fog, or in case of any other unexpected strain +on his resources.</p> + +<p>One of the first questions asked by the practical gas +maker will be: "What guarantee can you give that as +soon as we have erected plant, and got used to the new +process of manufacture, a sudden rise in the price of +oil will not take place, and leave us in worse plight +than we were before?" and the only answer to this is +that, as far as it is possible to judge anything, this +event is not likely to take place in our time. A year +ago the prospects of the oil trade looked black, as the +output of American oil was in the hands of a powerful +ring, who seemed likely also to obtain control of the +Russian supplies; but, fortunately, this was averted, +and, at the present moment, the Russian pipe lines are +flooding the market with an abundant supply, which +those best able to judge tell us is practically inexhaustible, +so that prices may be expected to have a downward +rather than an upward tendency. But even +should a huge monopoly be created, I think I have +found a source of light at home which will hold its own +against any foreign illuminant in the market.</p> + +<p>For a long time I have felt that in this country we +had sources of light and power which only needed development, +and the discovery of the right way to use +them, in order to give an entirely new complexion to +the question of carbureting; and now by the aid of +the engineering skill and technical knowledge of Mr. +Staveley, of Baghill, near Pontefract, I think it is +found.</p> + +<p>At three or four of the Scotch iron works the Furnace +Gases Co. are paying a yearly rental for the right +of collecting the smoke and gases from the blast furnaces. +These are passed through several miles of +wrought iron tubing, diminishing in size from 6 feet +down to about 18 inches; and as the gases cool, so there +is deposited a considerable yield of oil.</p> + +<p>At Messrs. Dixon's, at Glasgow, which is the smallest +of these installations, they pump and collect about 60,000,000 +cubic feet of furnace gas per day; and recover, +on an average, 25,000 gallons of furnace oils per week, +using the residual gases, consisting chiefly of carbon +monoxide, as fuel for distilling and other purposes, +while a considerable yield of sulphate of ammonia is +also obtained. In the same way a small percentage of +the coke ovens are fitted with condensing gear, and +produce a considerable yield of oil, for which, however, +there is a very limited market, the chief use being for +lucigen and other lamps of the same description, and +for pickling timber for railway sleepers, etc.; the result +being that, four years ago, it could be obtained in +any quantity at 1/2d. per gallon, while since that it has +been as high as 21/2d. a gallon, but is now about 2d., +and shows a falling tendency. Make a market for this +product, and the supply will be practically unlimited, +as every blast furnace and coke oven in the kingdom +will put up plant for the recovery of the oil, and as +with the limited plant now at work it would be perfectly +easy to obtain 4,000,000 or 5,000,000 gallons per +annum, an extension of the recovery process would +mean a supply sufficiently large to meet all demands.</p> + +<p>Many gas managers have, from time to time, tried if +they could not use some of their creosote for gas producing, +but on heating it in retorts, etc., they have found +the result has generally been a copious deposit of carbon, +and a gas which has possessed little or no illuminating +value. Now, the furnace and coke oven oils +are in composition somewhat akin to the creosote oil, +so that at first sight it does not seem a hopeful field for +search after a good carbureter, but the furnace oils +have several points in which they differ from the coal +tar products. In the first place, they contain a certain +percentage of paraffin oil, and in the next, do not contain +much naphthalene, in which the coal tar oil is +especially rich, and which would be a distinct drawback +to their use.</p> + +<p>The furnace oil as condensed contains about 30 to 50 +per cent. of water, and in any case this has to be removed +by distilling; and Mr. Staveley has patented a +process by which the distillation is continued after the +water has gone off, and by condensing in a fractionating +column of special construction, he is able to remove +all the paraffin oil, a considerable quantity of cresol, a +small quantity of phenol, and about 10 per cent. of +pyridine bases, leaving the remainder of the oil in a +better condition, and more valuable for pickling timber, +which is its chief use.</p> + +<p>If the mixed oil so obtained, which we may call +"phenoloid oil," is cracked by itself, no very striking +result is obtained, the 40 percent. of paraffin present +cracking in the usual way, and yielding a certain +amount of illuminants, but if this oil be cracked in the +presence of carbon, and be made to pass over and +through a body of carbon heated to a dull red heat, +then it is converted largely into benzene, the most +<a name="Page_12690" id="Page_12690"></a>valuable of the illuminants, and also being the one to +which coal gas owes the largest proportion of its illuminating +power, it is manifestly the right one to use in +order to enrich it.</p> + +<p>On cracking the phenoloid oil, the paraffins yield +ethane, propane, and marsh gas, etc., in the usual way, +while the phenol interacts with the carbon to form +benzene—</p> + +<table align="center" cellspacing="3" cellpadding="2" summary=""> +<colgroup><col align="left"><col align="center"><col align="right"></colgroup> +<tr><th align="center">Phenol.</th><th></th><th align="center">Benzene.</th></tr> +<tr><td>C<sub>6</sub>H<sub>5</sub>HO + C</td><td> =<sub> </sub></td><td> C<sub>6</sub>H<sub>6</sub> + CO.</td></tr> +</table> + +<p>And in the same way the cresol first breaks down to +toluene in the presence of the carbon, and this in turn +is broken down by the heat to benzene.</p> + +<p>A great advantage of this oil is that the flashing +point is 110, and so is well above the limit, thus doing +away with the dangers and troubles inseparable from +the storage of light naphtha in bulk.</p> + +<p>In using this oil as an enricher, it must be cracked in +the presence of carbon, and it is of the greatest importance +that the temperature should not be too high, as +the benzene is easily broken down to simpler hydrocarbons +of far lower illuminating value. This fact is +very clearly brought out by a series of experiments I +have made, in which the phenoloid oil was cracked by +passing it through an iron tube packed with coke and +heated to various temperatures, the hydrocarbons being +much more easily broken up under these conditions +than if mixed with diluents, such as water gas:</p> + +<table align="center" cellspacing="3" cellpadding="2" summary=""> +<colgroup><col align="left"><col align="right" span="3"></colgroup> +<tr><th colspan="4" align="center">RESULTS OBTAINED ON CRACKING PHENOLOID OIL.</th></tr> +<tr><td colspan="4"> </td></tr> +<tr><td> </td><td align="center">I.</td><td align="center">II.</td><td align="center">III.</td></tr> + +<tr><td>Temperature.</td><td>600° C.</td><td>800° C.</td><td>1,000° C.</td></tr> +<tr><td>Volume of gas per gallon.</td><td>41.6 c.f.</td><td>76.8 c.f.</td><td>121.6 c.f.</td></tr> +<tr><td colspan="4"> </td></tr> +<tr><td colspan="4" align="center">COMPOSITION OF THE GAS.</td></tr> +<tr><td>Hydrogen.</td><td>34.0</td><td>36.0</td><td>37.0</td></tr> +<tr><td>Methane.</td><td>20.0</td><td>26.0</td><td>49.0</td></tr> +<tr><td>Olefines.</td><td>11.0</td><td>5.0</td><td>Nil.</td></tr> +<tr><td>Ethane.</td><td>16.0</td><td>9.0</td><td>Nil.</td></tr> +<tr><td>Carbon monoxide.</td><td>13.0</td><td>15.0</td><td>12.0</td></tr> +<tr><td>Carbon dioxide.</td><td>2.0</td><td>4.0</td><td>2.0</td></tr> +<tr><td>Oxygen.</td><td>2.0</td><td>1.0</td><td>Nil.</td></tr> +<tr><td>Nitrogen.</td><td>2.0</td><td>4.0</td><td>Nil.</td></tr> +</table> + +<p>This analysis shows that if the temperature is allowed +to reach a cherry red, complete decomposition of the +illuminating hydrocarbons is taking place, and a gas +of practically no illuminating value results. The power +of regulating the temperature and the body of carbon +as a cracking medium in the Van Steenbergh +water gas plant especially fits it for using this oil, and +removes the objections which could have been urged +against the lighter naphthas.</p> + +<p>This oil is at present not in the market, but given a +demand, it can be produced in four months, at the +latest, in very large quantities, as the apparatus is very +easy and cheap to erect, and the crude material can be +plentifully obtained.</p> + +<p>If this oil becomes, as I think it will, an important +factor in the illumination of the future, it will mark as +important an era in the history of our industries as +any which the century has seen, as, by using it, you +are giving smoke a commercial value, and this will do +what the Society of Arts and the County Council have +failed in—that is, to give us an improved atmosphere. +If I were lecturing on an imaginary "Hygeia," I +should point out that the smoke of London contains +large quantities of these oils, and they, by coating the +drops of mist on which they condense, give the fog +that haunts our streets that peculiar richness which is +so irritating and injurious to the system, and, further, +by preventing the water from being again easily taken +up by the air, prolong the duration of the fog. Make +this oil a marketable commodity, and another twenty +years will see London without a chimney; underground +shafts will be run alongside the sewers; into these +shafts by means of a down draught all the products of +combustion from our fires will be sucked by local +pumping stations, and the oil condensing in the tubes +will serve in turn to illuminate our streets, instead of +performing its former function of turning day into +night and ruining our health; but as I am not at all +sure of the engineering possibilities of such a scheme, +I will leave its discovery to some other abler prophet +than myself.</p> + +<p class="ctr">(<i>To be continued</i>.)</p> + +<a name="FN16_1"></a><a href="#FN16anchor_1">[1]</a><div class="note"> Lectures recently delivered before the Society of Arts, London. From the <i>Journal</i> of the Society.</div> + + + +<hr /> + +<a name="ref7"></a><h2>ELECTRICAL LABORATORY FOR BEGINNERS.</h2> + +<h3>By GEO. M. HOPKINS.</h3> + +<p>It is only when theory and practice, study and experiment, +go hand in hand that any true progress is +made in the sciences. A head full of theory is of little +value without practice, and although the student may +apply himself with all his energies for years, his time +will, to a great extent, have been spent in vain, unless +he by experiment rivets the ideas he gains by his +study.</p> + +<p>In the study of electricity, for example, let the student +try to remember the position a magnetic needle +will take when placed below or above a conductor +carrying a current which flows in a known direction. +Without experiment there are nine chances of forgetting +to one of remembering; but let the student try +the experiment, and he will ever afterward be able to +determine the direction in which the current is flowing +by the position taken by the needle relative to the conductor.</p> + +<p>In the matter of ampere turns, as another example, +it is quite simple to assert that a ten ampere current +carried once around a soft iron bar produces the same +result as a one ampere current carried ten times around +the bar, but how much more strongly is this fact +stamped upon the memory when its truth is established +by experiment?</p> + +<p>Reading about a fact, or commiting to memory the +literature of a subject, is desirable and even necessary, +but knowledge of this character partakes more of the +nature of faith than that gained by actual experience.</p> + +<p>Let the reader learn first all that can be learned by +the aid of this simple apparatus, then branch out to +allied things, making each step as thorough as possible, +and before long he will be congratulating himself on +having gained at least an elementary knowledge of +electricity.</p> + +<p>Very little can be done in the way of electrical experiment +without an electrical generator of some sort, + +and nothing at present known can excel a battery for +this purpose. Although not the most desirable battery +for all purposes, that shown in Fig. 1 is the most +desirable for the amateur who desires a strong current +for a short time. It is formed of two plates, a, of +carbon arranged on opposite sides of an amalgamated +plate, b, of zinc, and separated from the zinc by strips +of wood. Bars of wood are placed outside of the +carbon plates, and the four bars are fastened together +by two common wood screws, thus clamping all the +bars and the zinc and carbon plates securely in the +position of use.</p> + + +<p class="ctr"><img src="./images/12-battery.png" width="245" height="392" +alt="FIG. 1.—SIMPLE BATTERY."></p> +<p class="ctr">FIG. 1.—SIMPLE BATTERY.</p> + + +<p>Between the zinc plate and the wooden bar adjoining +it is inserted a strip of copper, c, for leading away +the current from the zinc pole of the battery, and between +the carbon plates and the wooden bars is inserted +a doubled strip of copper, d, forming a connection +between the two carbon plates, and at the same +time serving as a conductor for conveying away the +current from the carbon pole of the battery. This element +is to be plunged into a tumbler of sufficient +depth to allow the wooden bars to rest on the upper +edge of the tumbler, while the lower ends of the +plates are one-half or three-quarters inch above the +tumbler bottom.</p> + +<h3>THE SOLUTION.</h3> + +<p>In the tumbler is placed a solution consisting of two-thirds +of a tumblerful of water, two ounces of bichromate +of potash, and two ounces of sulphuric acid. +The bichromate of potash should be dissolved first, +then the acid should be slowly and carefully added. +As the solution heats, it is well to prepare it in an +earthen vessel, which is not liable to break. These +materials should be used with great caution, as they +are poisonous, and the solution is very corrosive, destroying +almost everything with which it comes in contact. +With proper care, however, there is no danger +in using the solution. It gives off no poisonous vapors. +Of course it is advisable to make the solution in +quantities of a gallon or so when convenient.</p> + +<p>The battery compound known as the C and C battery +compound, sold in tin cans at most electric stores, is +very convenient. It is only necessary to place two or +three ounces of it in the tumbler and add the amount +of water above mentioned, stirring the solution with a +glass or rubber rod until the crystals are dissolved.</p> + +<p>A caution is necessary here. If only a portion of the +contents of the can are to be dissolved, it will be +necessary to place the remainder in a glass or earthen +jar, as it will absorb moisture and rapidly eat its way +through the can.</p> + +<p>The zinc plates should be amalgamated by plunging +them into the bichromate solution, then sprinkling on + +a minute quantity of mercury, rubbing it about by +means of a swab, until the entire exposed surface is +covered with mercury.</p> + +<h3>CONVENTIONAL SIGN FOR THE BATTERY AND +GALVANOMETER.</h3> + +<p>In making electrical diagrams it is necessary to frequently +represent a battery. It requires too much +time to make a sketch or drawing of a battery. Besides +this, the drawing of any particular kind of +battery might be misleading. A sign representing +the galvanic battery has been universally +adopted. It consists of a long, thin mark or dash, +representing the carbon electrode, and a shorter, +thick mark representing the zinc electrode, thus:<img src="./images/12-mini1.png" align="right" +width="35" height="94" alt="Battery Symbol"> <br clear="all"> +Where more cells are required, this +sign is repeated once for each cell, thus: <img src="./images/12-mini2.png" align="right" +width="90" height="99" alt="Battery Symbol 2"><br clear="all" /> +The galvanometer +is represented thus:<img src="./images/12-mini3.png" align="right" +width="119" height="69" alt="Galvanometer Symbol"><br clear="all" /></p> + +<p>By the use of the battery and a few articles such as may be found +anywhere, in addition to the pieces shown in Fig. 2, all the +experiments here described may be performed. As these pieces are shown +half size in the diagrams, Fig. 2, and about full size in the +perspective views, it will be unnecessary to give dimensions. The +bobbins, A A, are wound with No. 24 double cotton-covered magnet wire, +the terminals being soldered to eyes formed of pieces of spring wire +bent so as to form helical coils of two turns each, with the ends +inserted in holes drilled in heads of the spools. These coiled wires +answer a good purpose in making electrical connections. The magnet +frame, B, consisting of the cores and the yoke formed integrally of a +single soft gray iron casting, is adapted to receive the bobbins, A A, +to form an electro-magnet. The yoke of the magnet is provided with a +thumb-screw, e, for securing the magnet to the motor frame, C. The +latter is furnished with a base piece, f, a slotted standard for +receiving the clamping screw, e, of the magnet, and the standards, g, +in which is journaled the armature, h, on a wire extending through +both the standards and the armature.</p> + +<p>The armature, h, consists of an oblong rectangular soft iron frame +having at one end a small pulley and at the other end an elliptical +boss, i, which is arranged obliquely to form in conjunction with the +spring, j, a circuit closer and opener, which closes the circuit twice +during each revolution of the armature, just as one of its side bars +is approaching the poles of the magnet and breaks it as the bar comes +opposite the poles of the magnet.</p> + +<p>The spring, j, is bent into a loop and its lower end is inserted in +a wooden plug driven into a hole in the base piece, f.</p> + +<p>In the upper part of Fig. 2 are shown two telegraph instruments +less the bobbins. Each instrument (Fig. 14) consists of a wooden base, +k, a right angled soft iron bar, l, having the central part of its +upper end brought to an obtuse angle, an armature, m, fitted loosely +to the angled end of the bar, a notched brass standard, n, for +limiting the movement of the armature, a retractile spring for lifting +the armature, a spring key, o, pivotally secured to the base by a +common wood screw, and a contact point projecting from the base under +the key.</p> + +<p>Besides these there is a D shaped block, to answer as a frame to +the galvanometer, a common pocket compass, E, fitted to a circular +cavity in the top of the block, D, a permanent U magnet, F, a bundle +of soft iron wires, G, and two copper strips, H.</p> + +<p class="ctr"><a href="./images/12-app.png"><img src="./images/12-app_th.png" width="452" height="398" +alt="Apparatus Drawings"></a></p> + + +<h3>DECOMPOSITION OF WATER.</h3> + +<p>To illustrate the decomposition of water, connect the +copper strips, H H, to the poles of the battery by +means of wires, as shown in Fig. 3, and insert them in +a tumbler of water acidulated with a few drops of sulphuric +acid. Instantly bubbles will rise from the copper +strips, showing that gas is being disengaged from +the water. The strip connected with the carbon plate +will disengage oxygen, while the strip connected with +the zinc plate will disengage hydrogen.</p> + +<p class="ctr"><img src="./images/13-fig3.png" width="356" height="395" +alt="FIG. 3.—DECOMPOSITION OF WATER."></p> +<p class="ctr">FIG. 3.—DECOMPOSITION OF WATER.</p> + +<h3>SOLENOID.</h3> + +<p>By connecting one of the coils, A, with the battery +<a name="Page_12691" id="Page_12691"></a>by means of the wires, the action of a helix or solenoid +is shown. When so connected, the helix will draw up +with itself a barrel pen, or any light iron or steel +object. (See Fig. 4.) This is not a true solenoid, but it +is generally known by that name. In a true solenoid +one of the terminals is passed back through the center +of the coil.</p> + +<p class="ctr"><img src="./images/13-fig4.png" width="336" height="392" +alt="FIG. 4.—SOLENOID."></p> +<p class="ctr">FIG. 4.—SOLENOID.</p> + +<h3>MAGNETIZATION OF STEEL.</h3> + +<p>By inserting in the solenoid a knitting needle, or any +bar of hardened or tempered steel, and sending a current +through the coil, the steel will become permanently +magnetized.</p> + +<h3>ELECTROMAGNET.</h3> + +<p>By placing the two coils, A, upon the magnet frame, +B, and connecting one terminal of each with the battery, +the remaining terminals being connected together, +as shown in Fig. 5, an electromagnet is formed +which will lift several pounds.</p> + +<p class="ctr"><img src="./images/13-fig5.png" width="470" height="396" +alt="FIG. 5.—ELECTROMAGNET."></p> +<p class="ctr">FIG. 5.—ELECTROMAGNET.</p> + + +<h3>ELECTRIC MOTOR.</h3> + +<p>By placing the magnet thus formed upon the motor +base, C, in front of the armature, h, as shown in Fig. +6, and connecting one terminal of the magnet with the +battery and the other with the clamping screw, e, of +the magnet, and by connecting the commutator spring, +j, with the remaining pole of the battery, the motor +will be made to rotate rapidly.</p> + +<p class="ctr"><img src="./images/13-fig6.png" width="546" height="394" +alt="FIG. 6.—MOTOR."></p> +<p class="ctr">FIG. 6.—MOTOR.</p> + +<h3>COMPASS AND MAGNETIC EXPERIMENTS.</h3> + +<p>By placing one end of the bar magnetized by the +solenoid near the compass contained by the cabinet +(Fig. 7) it will be seen that one end of the compass +needle is attracted. When the opposite end of the bar +is presented to the same end of the needle, that end of +the needle will be repelled and the opposite one attracted, +showing that like poles repel each other while +unlike poles attract.</p> + +<p class="ctr"><img src="./images/13-fig7.png" width="508" height="397" +alt="FIG. 7.—MAGNETIC EXPERIMENT."></p> +<p class="ctr">FIG. 7.—MAGNETIC EXPERIMENT.</p> + +<h3>GALVANOMETER.</h3> + +<p>By placing one of the coils, A, in the block, D, then +placing in the cavity in the top of the block the compass, +with the line marked N S arranged at right +angles to the axis of the coil, a serviceable galvanometer +will be formed (Fig. 8). By turning the galvanometer +so that the needle will point north and south +without the current passing, with N underneath one +end of the needle, and then connecting the poles of +the battery with the terminals of this galvanometer, a +deflection of the compass needle will be produced, the +direction of which depends upon the direction of the +current.</p> + +<p class="ctr"><img src="./images/13-fig8.png" width="599" height="323" +alt="FIG. 8.—GALVANOMETER."></p> +<p class="ctr">FIG. 8.—GALVANOMETER.</p> + +<h3>EXPERIMENTS SHOWING THE EFFECTS OF +RESISTANCE.</h3> + +<p>By placing the galvanometer in the circuit of the +battery, as shown in Fig. 9, and noting the deflection +of the needle, it will be ascertained that a certain +amount of current is flowing. Now, by placing in the +circuit, in addition to the galvanometer, the remaining +coil of the magnet, thus introducing considerable +resistance, the current will be diminished, as shown by +a smaller deflection of the needle.</p> + +<p class="ctr"><img src="./images/13-fig9.png" width="505" height="400" +alt="FIG. 9.—EFFECT OF RESISTANCE."></p> +<p class="ctr">FIG. 9.—EFFECT OF RESISTANCE.</p> + +<h3>RESISTANCE OF A FLUID CHANGED BY THE ADDITION +OF ANOTHER FLUID.</h3> + +<p>A very pretty and instructive experiment may be +performed by arranging the apparatus as shown in +Fig. 10, with the copper strips, H H, inserted in clean +water and the galvanometer placed in the circuit. The +deflection of the galvanometer needle will be very +slight, showing that the resistance of clean water is +considerable. A few drops of sulphuric acid or even +vinegar will increase the conductivity of the water so +as to produce a marked deflection of the galvanometer +needle.</p> + +<p class="ctr"><img src="./images/13-fig10.png" width="596" height="309" +alt="FIG. 10.—RESISTANCE OF FLUIDS."></p> +<p class="ctr">FIG. 10.—RESISTANCE OF FLUIDS.</p> + +<p>Common salt added to the water will produce the +same effect.</p> + +<h3>MAGNETIC ELECTRIC INDUCTION.</h3> + +<p>By placing one of the coils, A, on the magnet frame, +B, and connecting it by the wires with the galvanometer, +arranged as before described, and bringing the +permanent magnet, F, suddenly against the poles of +the magnet, as shown in Fig. 11, a current will be induced +in the coil, which, in passing through the galvanometer, +causes the needle to be deflected in one +direction, and when the permanent magnet is suddenly +removed from the electro-magnet, a current will be +set up in the opposite direction, which will cause a deflection +of the needle of the galvanometer in the +opposite direction.</p> + +<p class="ctr"><img src="./images/14-fig11.png" width="342" height="393" +alt="FIG. 11.—MAGNETO-ELECTRIC INDUCTION."></p> +<p class="ctr">FIG. 11.—MAGNETO-ELECTRIC INDUCTION.</p> + +<h3>INDUCTION COIL.</h3> + +<p>By placing both coils, A, upon the bundle of soft +iron wires, G, connecting one of them with the terminals +of the battery, as shown in Fig. 12, and holding +the terminals of the other coil in the moistened thumb +and fingers of the two hands, when the battery circuit +is opened and closed by touching one of the wires to +the battery, and removing it, a slight shock will be +<a name="Page_12692" id="Page_12692"></a>felt from the coil which is disconnected from the battery. +By placing a coarse file in the circuit and drawing +one of the terminals along the file the circuit will +be rapidly interrupted. This shock is due to the current +induced in the detached coil by the magnetism of +the bundle of wires.</p> + +<p class="ctr"><img src="./images/14-fig12.png" width="591" height="241" +alt="FIG. 12.—INDUCTION COIL."></p> +<p class="ctr">FIG. 12.—INDUCTION COIL.</p> + +<h3>EXTRA CURRENT.</h3> + +<p>An experiment showing the extra or self-induced current +consists in arranging the motor as shown in Fig. +6, and connecting wire with each conductor leading +from the battery to the motor, as shown in Fig. 13. If +these wires are grasped one in each hand while the motors +is in motion, a slight shock will be felt, providing +the hands are moistened.</p> + +<p class="ctr"><img src="./images/14-fig13.png" width="591" height="241" +alt="FIG. 13.—EXTRA CURRENT."></p> +<p class="ctr">FIG. 13.—EXTRA CURRENT.</p> + +<h3>TELEGRAPH SOUNDERS AND KEYS.</h3> + +<p>The cabinet contains material for two telegraph +sounders and keys which will enable the user to establish +a short telegraph line with a single cell of battery. +The armature, m, may be lifted from its pivot so as to +permit of slipping one of the coils, A, on to the round +magnetic core of the sounder. The armature is then +replaced, as shown in Fig. 14, and the small retractile +spring at the rear of the instrument is arranged to +draw down the shorter arm of the armature lever. +One of the terminals of the coil, A, is connected with + +the turned up pivoted end of the telegraph key, o, on +the same base. The other terminal is connected with +one pole of the battery and the contact point of the +key is connected with the other pole of the battery, as +shown. By swinging the key laterally, so as to remove +it from the contact point, it will be found that every +touch of the key produces a movement of the sounder +lever. To connect the two instruments together upon +a line, it is only necessary to connect the two keys +with one wire and the terminals of the two coils with +another wire, cutting one of these wires and inserting +the battery.</p> + +<p class="ctr"><img src="./images/14-fig14.png" width="596" height="365" +alt="FIG. 14.—TELEGRAPH KEYS AND SOUNDERS."></p> +<p class="ctr">FIG. 14.—TELEGRAPH KEYS AND SOUNDER.</p> + + +<p>As soon as the operator ceases to work his instrument +he should place the key in contact with the contact +point, and cause it to remain there by slipping the end +of the key under the head of the screw provided for +that purpose. The other operator can then proceed to +send his message.</p> + +<p>Those who desire to practice telegraphy should learn +the Morse telegraphic code.</p> + +<h3>MAGNETIC FIGURES.</h3> + +<p>By arranging the coil so as to form an electro-magnet, +as before described, and holding the magnet under +a plate of glass sprinkled with fine iron filings, as +shown in Fig. 15, and then sending a current through +the magnet, at the same time jarring the glass by +striking it with a lead pencil, a magnetic figure will be +formed which is sometimes called the magnetic spectrum. +By connecting the terminals of the coils diagonally +with each other, and connecting the remaining +terminals with the battery, two like poles will be +formed, and the magnetic figures will have an entirely +different appearance, owing to the repulsion between +the two like polarities. Different figures may be produced +by using the solenoids without the iron cores.</p> + +<p class="ctr"><img src="./images/14-fig15.png" width="598" height="356" +alt="FIG. 15.—MAGNETIC FIGURES."></p> +<p class="ctr">FIG. 15.—MAGNETIC FIGURES.</p> + +<h3>EXPERIMENT SHOWING THE CURRENT.</h3> + +<p>By removing the coil, A, from beneath the compass, +E, and connecting the ends of the transverse wire, +a' a', with the battery Fig. 16, then lifting the plates +of the battery out of the solution and allowing the +needle to come to rest, it will be found upon inserting +the plates of the battery in the solution, very gradually, +that the deflection of the needle will increase with +the increase of plate surface submitted to the action + +of the battery fluid; and if, when the greatest deflection +is reached, the coils or solenoids are introduced +into the circuit, one after the other, it, will be found +that each added coil diminishes the current, as will be +shown by the diminished deflection of the needle.</p> + +<p class="ctr"><img src="./images/14-fig16.png" width="300" height="397" +alt="FIG. 16.—EXPERIMENT SHOWING THE CURRENT."></P> +<p class="ctr">FIG. 16.—EXPERIMENT SHOWING THE CURRENT.</p> + + +<h3>MICROPHONE AND TELEPHONE.</h3> + +<p>Take two small carbon rods, p p, if procurable, if +not, use two ordinary nails, and connect them up in the +circuit of the battery; lay them upon a thin box so +that the rods or nails cross each other, as in Fig. 17; +insert the electromagnet in the circuit; move the +coils out a little beyond the ends of the cores, lay a +thin iron plate over the ends of the coils, then jar the +box upon which the bars, p p, are laid, or drop +a pin upon it, or scratch it with a piece of paper, and +the sound will be heard by placing the ear against the +iron plate resting upon the coils of the magnet.</p> + +<p class="ctr"><img src="./images/14-fig17.png" width="596" height="333" +alt="FIG. 17.—MICROPHONE AND TELEPHONE."></P> +<p class="ctr">FIG. 17.—MICROPHONE AND TELEPHONE.</p> + +<h3>ELECTRO METALLURGY.</h3> + +<p>Dissolve an ounce of sulphate of copper in a half +pint of water; add a few drops of sulphuric acid; +connect with the zinc pole of the battery the object to +be coppered. To the wire connected with the carbon +attach a small plate of copper. Hang the object and +the copper plate in the solution a short distance apart. +A deposit of copper will be quickly formed.</p> + +<h3>THE HEATING EFFECT OF THE CURRENT.</h3> + +<p>With a piece of very fine platinum wire (No. 36 or +40), placed in the circuit of the battery, the heating +effect of the current may be shown. A half inch of +No. 36 platinum wire will serve for the experiment. If +the battery is in good condition it will heat from 1/8 to +1/4 inch of the wire red hot. This is sufficient to +light gas or an alcohol lamp, also to ignite powder or +gun cotton.</p> + +<p>A short piece of a watch hair spring, or a piece of +very fine iron wire, if placed in the circuit will be +made very hot.</p> + +<h3>DUPLICATION OF BATTERIES.</h3> + +<p>Should the experimenter desire to go more deeply +into the effects of the current, he will need a more powerful +battery. The battery described has been made +on a very simple plan, to enable the amateur to copy it +without difficulty or great expense. There is no mystery +about the battery. Any one can make it. All that +is required is a plate of zinc, two plates of carbon, some +strips of wood and copper, and two common wood +screws for each cell. The tumblers may be had anywhere.</p> + +<p>Although it is advisable to use insulated wire for +making the electrical connections, bare wires may be +used if care is taken in arranging them, so that they +will not touch each other or other metallic objects +which would complete the circuit.</p> + +<p>It will be found convenient if the elements of the +<a name="Page_12693" id="Page_12693"></a>battery are arranged upon a frame of some sort, by +means of which they may be raised or lowered all together, +and supported at any desired height.</p> + +<hr /> + +<a name="ref8"></a><h2>THE ACTION OF THE SILENT DISCHARGE +ON CHLORINE.</h2> + +<p>Arguing from the fact that oxygen gas, when subjected +to the silent discharge, partially undergoes +condensation into ozone, it seemed possible, says Mr. +H.M. Vernon, in the <i>Chemical News</i>, that other elementary +gases, as chlorine and bromine vapor, might +undergo an analogous change when subjected to the +same treatment. A glass tube, with a U-shaped index +of fine bore glass tubing, was filled with purified and +dried chlorine. After passing a current of the gas +through the tube for some time, the end was sealed in +the blowpipe flame. The tube was then warmed slightly, +and a few bubbles of gas thus driven out. The end +of the index tube dipped under strong sulphuric acid +saturated with chlorine gas, so that, on cooling, a short +column of the acid was drawn up. This served as an +index for any changes of volume which might take +place in the chlorine in the tube. A silent discharge of +electricity was then passed. The volume of the gas +was observed to increase slightly, but afterward it remained +quite constant, even after the discharge had +been passed for several hours. We may therefore conclude +that no allotropic change takes place when chlorine +gas is subjected to the silent discharge of electricity, +the initial increase of volume being merely due to +the heating effect the discharge has upon the gas. Into +another similar tube, filled with chlorine, was introduced +a small quantity of liquid bromine.</p> + +<p>The tube thus contained chlorine saturated with bromine +vapor. The silent discharge on being passed +through this tube did not produce any different effect +than for chlorine alone. So we may conclude that bromine +vapor also does not undergo any allotropic condensation +when subjected to the influence of a silent +discharge of electricity. The fact that oxygen gas is +capable of undergoing condensation while chlorine and +bromine are not is easily explained. The oxygen atom, +being divalent, is capable of uniting itself to two other +atoms of oxygen or other elements, and thus with +oxygen forming ozone. The atoms of chlorine and +bromine, however, being only monovalent, have all +their affinity satisfied when they are united to a single +other atom of chlorine and bromine. It is not possible, +therefore, that condensation can take place if the atoms +remain monovalent. Hydrogen gas and iodine vapor +are in a similar manner debarred from undergoing +condensation. Mr. Vernon, therefore, comes to the +conclusion that it is most improbable that any other element +but oxygen will be found capable of undergoing +molecular condensation when in the gaseous state and +subjected to the silent discharge.</p> + +<hr /> + +<a name="ref2"></a><h2>ESTIMATING CARBON IN ORGANIC +SUBSTANCES.</h2> + +<h3>By J. MESSINGER.</h3> + +<p>This is an improvement on the author's method of +two years ago. The method is now applicable to compounds +with which previously low results were obtained.</p> + +<p>The substance is weighed into a small tube 24 mm. +long and 11 mm. wide, and is then introduced into the +decomposition flask, which contains 6 to 8 grms. of +chromic acid, care being taken that the chromic acid +does not come into contact with the substance under +analysis. The decomposition flask is fitted with a +thistle funnel, and is connected to the reversed condenser +and apparatus shown in the figure. Fifty c.c. +of concentrated sulphuric acid are run into the flask. +During the whole of the operation a gentle current of +air (free from carbon dioxide) is passed through the apparatus. +The asbestos plate underneath the flask is +then warmed, and thus the flask and contents are +warmed by radiant heat from the plate alone until the +sulphuric acid darkens. At this point, where decomposition +of the organic substance begins, the flame is +entirely removed. The carbon dioxide (with some carbon +monoxide) passes through the condenser and then +over a heated mixture of copper oxide and lead chromate +contained in a tube 15 cm. long. The gas (CO<sub>2</sub>) +then passes through a U-tube, in one limb of which is +sulphuric acid, in the other glacial phosphoric acid.</p> + +<p class="ctr"><img src="./images/15-app.png" width="600" height="312" +alt="APPARATUS FOR THE ESTIMATION OF CARBON IN ORGANIC SUBSTANCES."></p> +<p class="ctr">APPARATUS FOR THE ESTIMATION OF CARBON IN ORGANIC SUBSTANCES.</p> + +<p>Thus dried it passes through weighed potash bulbs, +after which is placed for safety a small tube containing +soda lime and phosphoric acid. After the lapse of +about twenty minutes, warming may be once more proceeded +with in the same manner as before, and after +about two and one-half hours the asbestos plate may +be placed directly below the flask, and more strongly +heated. The whole operation is very easily carried +out, and needs no watching.</p> + +<p>With substances containing halogens, it is advisable + +to place, after the copper oxide tube, a small washing +flask containing potassium iodide solution.</p> + +<hr /> + +<a name="ref1"></a><h2>NEW RACE OF DWARF DAHLIAS.</h2> + + +<p>The dahlia has held a prominent place among garden +flowers for many years, and it has received new +life in the acquisition of a section little expected by +cultivators, but peculiarly welcome. This class is the +outcome of much patient work on the part of Mr. T.W. +Girdlestone, the well known secretary of the National +Dahlia Society, who has for some time past devoted +much time to the improvement of the single +varieties. We had the pleasure a short time since of +receiving a photograph of this dwarf section of dahlias +from Messrs. J. Cheal & Sons, of Crawley, who have +purchased the stock, and this we have had engraved, as +it conveys an excellent idea of the height of the plant +and the profusion with which the flowers are produced. +The photograph was also of interest as containing +a portrait of Mr. Girdlestone, which we are +sure will be welcome to many of our readers. The +plants of this race are very dwarf, not exceeding +twelve inches in height, bushy, spreading and exceedingly +free in flowering, the range of varieties being at +present limited to twelve. The blooms are of medium +size, and the colors are distinct and rich, more particularly +the scarlet and crimson shades, which can be employed +to immense advantage in the flower garden. +The heavy formal show varieties are of little value for +planting in trim beds and borders. Many of the decorative +or cactus varieties are too coarse in growth to +be of much value in the flower garden. Therefore, this +Liliputian race should find favor with those who wish +for showy and novel effects in the garden during the +summer months.</p> + +<p class="ctr"><a href="./images/15-dahlia.png"> +<img src="./images/15-dahlia_th.png" width="288" height="398" +alt="TOM THUMB SINGLE DAHLIAS."></a><br /> +TOM THUMB SINGLE DAHLIAS.</p> + +<p>There are no peculiarities of culture to contend with, +and the unusually dwarf habit of the plants specially +fits them for comparative small beds and borders. One +good way would be to fill a single bed with one or +more decided colors, as is now done with the tuberous +begonia, for the reason that these dahlias have flowers +similar in size to those of the tall-growing single varieties, +and bear them on stiff stalks well above the stems. +A mass of the crimson variety would produce a rich +glow of color infinitely finer than a mixture of undecided +hues. We anticipate a high degree of popularity +for these dwarf single or Tom Thumb dahlias, and +there is a possibility of double varieties equally dwarf +which would be also welcome. The great fault of the +majority of dahlias already in cultivation is the tall +habit of the plants, but here we have dwarfness, a profusion + +of finely formed flowers, and varied and attractive +colors.—<i>The Gardeners' Magazine</i>.</p> + +<hr /> + +<a name="ref9"></a><h2>SOME WINNEBAGO ARTS.</h2> + +<p>In the Proceedings of the New York Academy of +Sciences an abstract is given of a paper on the above, +read by Dr. Frederick Starr:</p> + +<p>It is well known that a tribe may have peculiarities +in speech, in manners, in arts, that distinguish it at +once from its neighbors. The Haida carves slate as no +other tribe does. The elegant blankets of mountain +sheep wool from Chilcat are characteristic. The Hebrews +tested the enemy with the word <i>shibboleth</i>, and +found that he could only say <i>sibboleth</i>. A twist of +the tongue in pronouncing a word is a small matter, +but, small as it is, it may be perpetuated for ages.</p> + +<p>Such a perpetuation of a tribal peculiarity has been +aptly called an ethnic survival. Some of the advanced +linguists of the present day are beginning to query +whether the group of modern languages of the Aryan +family are not examples of such ethnic survival; +whether the differences between French and Italian +and Spanish, Latin, Greek and Slavonic, are not due +to the difficulty various ancient tribes found in learning +to speak the same new and foreign language. To +draw an example of ethnic survival from another field +of science, consider the art of the French cave men. +The archĉologist finds in the caverns bones of various +mammals, teeth of cave bear, and antlers of reindeer +carved with animal figures. The art is <i>good</i> for a barbarous +people, but it is certainly barbarian art. The +range of designs is quite great: horses, bears, mammoths, +reindeer, are among the figures. The people +who did this work were an artistic people. To carve +and represent animal forms was almost a mania with +them. An ethnic impulse seems to have driven them +on to such work, just as a similar impulse drives the +Haida slate carver to-day; just as a similar impulse +has driven the Bushman to cover the walls of his +caves in South Africa with pictures whose boldness +and fidelity are the amazement of all who see them.</p> + +<p>We have, then, in the French cave dwellers a people +who had a well defined art, and who, as art workers, +were isolated and unlike all neighbors. An eminent +English scientist believes that neither they nor +their art are gone. There is a people who to-day lives +much as a cave man of France lived so long ago, who +hunts and fishes as he did, who dresses as he did, who +builds houses in whose architecture some think they +can see evidence of a cavern original, who above all +still carves batons from ivory, and implements from +bone, adorning them with skillfully cut figures of animals +and scenes from the chase. This people is the +Eskimo. If Dawkins' view is true, we have in the +Eskimo carvings of to-day a true ethnic survival—an +outcropping of the same passion which displayed itself +in the mammoth carving of La Madelaine.</p> + +<p>Scarcely anything in the range of American antiquities +has caused more wonder and led to more discussion +than the animal mounds of Wisconsin. We do not +pretend to explain their purpose. Perhaps they were +village guardians; perhaps tribal totems marking territorial +limits; some may have been of use as game +drives; some may even have served as fetich helpers in +the hunt, like the prey gods of Zuñi. We may never +know their full meaning. It is sufficient here for me to +remind you what they are and where. They are nearly +confined to a belt of moderate width stretching through +Wisconsin and overlapping into Minnesota and Iowa. +Within this area they occur by hundreds. Dr. Lapham +published a great work on the effigy mounds in +1855, in which he gave the results of many accurate +surveys and described many interesting localities. +Since his time no one has paid so much attention to +the effigies as Stephen D. Peet, editor of the <i>American +Antiquarian</i>, whose articles have during this year been +presented in book form. Mr. Peet has paid much attention +to the kind of animals represented, and has, it +seems to us, more nearly solved the question than any +one else. He recognizes four classes of animals—land +animals or quadruped mammals, always shown in profile; +amphibians, always shown as sprawling, with all +four feet represented; birds, recognized by their +wings; and fishes, characterized by the absence of +limbs of any kind. The land animals are subdivided +into horned grazers and fur bearers. Of the many +species he claims to find, it seems to us the most satisfactorily +identified are the buffalo, moose, deer, or elk; +the panther, bear, fox, wolf and squirrel; the lizard +and turtle; the eagle, hawk, owl, goose and crane; +and fishes. One or two man mounds are known, although +most of those so-called are bird mounds—either +the hawk or the owl. Sometimes, too, "composite +mounds" are found. Nor are these mounds all +that are found. Occasionally the same forms are found +<i>in intaglio</i>, cut into the ground instead of being built +above it, but just as carefully and artistically made. +Notice, in addition to the form of these strange earth +works, that they are so skillfully done that the attitude +frequently suggests action or mood. Nor are they +placed at random, but are more or less in harmony +with their surroundings. Remember, too, their great +number and their large size—a man 214 feet long, a +beast 160 feet long, with a tail measuring 320 feet, a +hawk 240 feet in expanse of wing.</p> + +<p>They are <i>unique</i>. To be sure, there are in Ohio +three effigies, in Georgia two, and in Dakota some +bowlder mosaics in animal form. None of these, however, +are like the Wisconsin type. The alligator and +serpent of Ohio are different in location and structure +from the Wisconsin mounds, and are of designs peculiar. +The bird mound in the Newark circle is more +like a Wisconsin effigy, but is associated with a type of +works not found in the effigy region. The birds of +Georgia are different in conception, in material, and +in build. The mosaics of Dakota are simply outlines +of loose bowlders.</p> + +<p>It seems to us that the effigy builders of Wisconsin +were a peculiar tribe, unlike their mound-building +neighbors in Ohio or the South; that they were a people +with a passion for representing animal figures. This +passion worked itself out in these earth structures. +That a single tribe should be thus isolated in so remarkable +a custom is no more strange than that the +Haida should carve slate or the Bushman draw his +pictures on his cavern walls.</p> + +<p>Who were the effigy builders? This is a question +often asked and variously answered. Some writers +would refer them to the Winnebagoes, or, if not to +<a name="Page_12694" id="Page_12694"></a>them directly, to some Dakota stock from which the +Winnebagoes have descended.</p> + +<p>Formerly I was a frequent visitor to the Sac and +Fox Reservation in Iowa. About 400 of the tribe are +left. To an unusual degree they retain the old dress, +language, arts and dances. With them lived a few +Winnebagoes. In general the lives of the two peoples +are similar. Certain arts common to both of them +particularly interested me. They are the making of +sacks of barks and cords, and the weaving of bead +bands for legs and arms, upon the <i>ci-bo-hi-kan</i>. Of +the bark sacks there are several patterns, the simplest +being made of splints of bark passing alternately over +and under each other. Another kind, far more elaborate +in construction, is before you. Yet more elaborate +ones are made entirely of cords. The first of +these I saw was in old Jennie Davenport's wikiup. It +was of white and black cords, and the black ones were +so manipulated as to form a pattern—a line of human +figures stretching across the sack. Jennie would not +sell it, as she said, "It is a Winnebago woman's sack; +Fox woman not make that kind." I found afterward +a large variety of these Winnebago sacks, and all were +characterized by patterns of men, deer, turtles, or +other animals. Not one Fox sack of such pattern was +to be found, though many elaborate and beautiful +geometrical designs were shown me.</p> + +<p>The most beautiful work done on this reservation is +the bead weaving on the ci-bo-hi-kan—woven work, +<i>not</i> sewed, remember. In appearance the result is like +the Iroquois wampum belts, but the management of +the threads is dissimilar. The Sac and Fox patterns +are frequently complex and beautiful, but always geometrical. +We have seen hundreds of them, but none +with life forms. The Winnebago belts, made in exactly +the same way, frequently, if not always, present +animals or birds or human beings.</p> + +<p>This, it seems to us, is very curious. Here are people +of two tribes living side by side, with the same +mode of life and the same arts, but in their art designs +so diverse. It is a case parallel to that of the +old effigy builders, a people who have a passion for depicting +animal forms—a passion not shared by their +neighbors.</p> + +<p>If this were the only evidence that the Winnebagoes +built the effigy mounds, or that their ancestors did so, +it would have no great weight. But the claim has +been made already on other grounds. This being the +case, we think that this adds something to the testimony, +and we ask, <i>Have we here an ethnic survival?</i></p> + +<p>At the close of the paper Dr. Starr exhibited a number +of fine specimens of Indian handiwork, including +woven work, bags, belts, etc.</p> + +<p>Dr. Newberry explained that these mounds were not +sepulchral, like many others in the Ohio and Mississippi +valleys. Geologically speaking, man is very recent. +The early inhabitants of America may have +originally come from the East, but, if so, they were cut +off from that part of the world at a very early date. +The development of the tribes in America was complete +and far-reaching. Copper and lead mines were +worked, the forests removed, and large tracts given +over to the cultivation of corn, grain, etc. This was +the mound age, and the constructions were certainly +abandoned over one thousand years since. The Pueblo +Indians now existing in Arizona and New Mexico +took their origin from Central America, and spread as +far north as Salt Lake, Utah, and south as far as Chili. +Their structures were permanent stone buildings, +many of which still exist in a good state of preservation.</p> + +<p>Professor Munroe found rocks on the Ohio river, +near the Pennsylvania line, inscribed with figures of +men, horses and other animals. At low water these +figures can be distinctly observed.</p> + +<hr /> + +<a name="ref10"></a><h2>THE PHILOSOPHY OF CONSUMPTION.</h2> + +<h3>By Dr. J.S. CHRISTISON, Chicago.</h3> + +<p>A proclamation by an eminent physician that he +has discovered a specific cure for consumption in its +most prevalent and insidious form, known as tuberculosis, +might well create a deep and universal interest, +since there are comparatively few of us that do not +have this deadly enemy within the limits of our cousin +kinship. And if German slaughter house statistics are +to be taken as representative, no less than ten per +cent. of our domesticated horned cattle are a prey to +the same disease, though seldom discovered during +life. This fact would suggest that tubercular consumption +is still more prevalent in the human family +than has yet been supposed, and that many carry it +under the cover of other maladies.</p> + +<p>But unfortunately for any hope for a specific remedy, +the preponderance of evidence points to the fact that +consumption is much more a product of individual +habits and social and climatical conditions than a resultant +of any one agency. Indeed, the causative evils +may vary not only in their degree, but also in their +number and order of action in the period of its +evolution.</p> + +<p>If it were hereditary in the sense that it is transmitted +by the blood as a specific germ or virus, then the +offspring of consumptives would have an attenuated +form of the disease, which, by reasoning from analogy, +ought to secure them exemption from any further danger +along that line. Such, however, is not the case. +But if we say a special fitness is inherited, then we can +understand how the offspring of consumptives are +prone to develop it, since they are not only born with +hereditary qualifications, but not infrequently they +are cradled amid the very agencies which fostered +the evil in their parents, if, indeed, they were not +primarily causative.</p> + +<p>That the contribution of heredity to consumption is +great is undoubtedly the case, and, more than any +other factor, it would seem to have a directing power +in the army of inducing evils. But the fact that the +greater number of the offspring of consumptives escape +the disease, even where the general family resemblance +is quite pronounced, is readily explained by +the difference in personal habits, the circumstances of +different periods or the domestic regulations instituted +by medical counsel. Also the fact that consumptives +so frequently spring from neurotic parentage and the +victims of dissipation, especially alcoholic, still farther +goes to show that the hereditary element is essentially +a reduced power of resistance to formative evils, and +that as a negative condition it may hold the balance + +of power in focusing the forces. Thus, heredity, in +disease, can be understood as in no sense implying a +specific force, but rather an atonic or susceptible condition, +varying in its precise character and producing +a <i>pars minoris resistentiĉ</i>—a special weakness in a +special way.</p> + +<p>That the germ <i>bacillus</i> does not originate consumption +there can be no doubt, unless consumption is not +to be regarded as a disease until it is full fledged, for +otherwise the germ would be present in the earlier +formations, as well as the later, which, according to +good authority, is not the case. But that this parasite +has a special affinity for consumptive tissue there is no +question, and that it thrives therein with great rapidity, +hastening retrogressive changes, is also to be +granted. But, as yet, this is all we are entitled to +believe.</p> + +<p>We thus see that the lines of successful treatment +must be both constitutional and local; that the constitutional +cannot be specific, and the strictly local cannot +be curative. The constitutional must be of a +negative and positive character, having regard to the +support of the healthy remnant, and which will require +correction of any deficiency whatsoever in order to remove +the morbid constitutional habit. The local will +be cleansing of the affected organs from the germs and +morbid products.</p> + +<p>The evident selective affinity of Koch's lymph for +tuberculous tissue may enable it, in certain cases, to +effectually seal the arterial capillaries about the affected +parts, owing to the intense vaso-motor disturbance +produced. This would starve the germs, which, with +the tubercular matter, may be expectorated through +the moisture and motion of the lungs. In incipient +cases the tubercles might be as readily absorbed as +catgut ligature, and the germs, if any, fall to phagocytic +prey. The Koch lymph is evidently not a poison +to the germs, and probably has no other action on the +affected organs than that of an irritant, having a selective +affinity by virtue of the kinship with its contents. +This theory of its action is supported by our +common knowledge of the power of pyogenic agents +to awaken old or slumbering inflammations, and the +fact that septic fevers, such as small-pox, have been +known to leave the consumptives with the last stages +free from every symptom.</p> + +<hr /> + +<h3>THE SCIENTIFIC AMERICAN</h3> + +<h3>Architects and Builders Edition.</h3> + +<p>$2.50 a Year. 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