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diff --git a/15708.txt b/15708.txt new file mode 100644 index 0000000..40c2dc4 --- /dev/null +++ b/15708.txt @@ -0,0 +1,4762 @@ +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: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN *** + + + + +Produced by Juliet Sutherland and the Online Distributed Proofreading +Team at www.pgdp.net. + + + + + +[Illustration] + + + + +SCIENTIFIC AMERICAN SUPPLEMENT NO. 794 + + + + +NEW YORK, March 21, 1891 + +Scientific American Supplement. Vol. XXXI., No. 794. + +Scientific American established 1845 + +Scientific American Supplement, $5 a year. + +Scientific American and Supplement, $7 a year. + + * * * * * + + + + +TABLE OF CONTENTS + + +I. BOTANY.--New Race of Dwarf Dahlias.--A new and valuable + flowering plant, with portrait of the introducer.--1 illustration. + +II. CHEMISTRY.--Carbon in Organic Substances.--By J. MESSINGER.-- + An improved method of determining carbon by inorganic + combustions.--1 illustration. + +III. 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. + + Best Diameter of Car Wheels.--The size of car wheels from the + standpoint of American engineering.--A plea for a moderate sized + wheel. + + Improved Overhead Steam Traveling Crane.--A crane constructed + for use in steel works.--Great power and range.--3 illustrations. + + Some Hints on Spiking Track.--A most practical article for telling + exactly how to conduct the operation on the ground.--1 illustration. + +IV. ELECTRICITY.--Electrical Laboratory for Amateurs.--By GEO. + M. HOPKINS.--A simple collection of apparatus for conducting a + complete series of electrical experiments.--17 illustrations. + + The Action of the Silent Discharge on Chlorine.--How an electric + discharge affects chlorine gas.--An important negative result. + +V. ETHNOLOGY.--Some Winnebago Arts.--An interesting article + upon the arts of the Winnebago Indians.--A recent paper before + the New York Academy of Sciences. + +VI. 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. + +VII. 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. + +VIII. 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. + + The Experiments at the Annapolis Proving Grounds.--The recent + tests at Annapolis described and illustrated.--Views of the + projectiles, plates, etc.--3 illustrations. + +IX. PHYSICS.--Araeo-Picnometer.--An entirely novel form of hydrometer, + of very extended use and application.--1 illustration. + +X. TECHNOLOGY.--Fabric for Upholstery Purposes.--Full technical + description of the method of producing a new and characteristic + fabric.--1 illustration. + + Gaseous Illuminants.--By Prof. VIVIAN B. LEWES.--Continuation + of this important article, treating of the water gas and special + processes, with analyses. + + Glove Making.--Early history of glove making in America.--Its + present aspects and processes. + + Reversible Ingrain or Pro-Brussels Carpet.--An imitation of + Brussels carpet on the Ingrain principle.--Full description of the + process of making.--3 illustrations. + + The Manufacture and Use of Plaster of Paris.--An excellent + treatment of a subject hitherto little written about.--Full + particulars of the manufacturing process. + + * * * * * + + + + +IMPROVED OVERHEAD STEAM TRAVELING CRANE. + + +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 _Industries._ +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. + +[Illustration: IMPROVED OVERHEAD TRAVELING CRANE] + +[Illustration: FIG. 2 SIDE ELEVATION] + +[Illustration: FIG. 3 PLAN] + + * * * * * + + + + +BEST DIAMETER CAR WHEELS.[1] + +[Footnote 1: By Samuel Porcher, assistant engineer motive power +department, Pennsylvania Railroad. Read at a regular meeting of the +New York Railroad Club, Feb. 19, 1891.] + + +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. + +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. + +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. + +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. + +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. + +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. + +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. + +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 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. + +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. + +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. + +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. + +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. + +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. + +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. + +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. + +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. + + * * * * * + + + + +A NEW INTEGRATOR.[1] + +[Footnote 1: A paper read before the University College Engineering +Society on January 22.--_Engineering_.] + +BY PROFESSOR KARL PEARSON, M.A. + + +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. + +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, _et praeterea nil_. 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. + +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. + +[Illustration: A NEW INTEGRATOR] + +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. + +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. + +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. + +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. + +Let me here lay down the conditions which seem essential to a +practical integraph. These are, I think, the following: + +1. The price must be such that it is within the reach of the ordinary +draughtsman's pocket. The Amsler's planimeter at L2 10s. or L3 may be +said to satisfy this first condition. The price for the first complex +integraph designed by Coradi was L24 to L30. The modified form in +which I show it to-night is estimated to cost retail L14. Till an +equally efficient instrument can be produced for L5 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. + +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. + +3. It must be capable of being used on the ordinary drawing board, and +of having a fairly wide range on it, i.e., it must not be limited to +working where the primitive is at one part only of the board. + +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. + +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. + +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. + +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: + + ---------+------------+-----------+----------------------------------- + | | | By integraph. + Radius | | By |--------+--------+--------+-------- + of | Calculated |Planimeter.| | Upper | | Upper + circle. | areas. | |Middle. | end. |Middle. | end. + | | |p=2 in. |p=2 in. |p=4 in. |p=4 in. + ---------+------------+-----------+--------+--------+--------+-------- + in. | | | | | | + 1 | 3.14159 | 3.140 | 3.140 | 3.138 | 3.120 | 3.120 + | | | | | | + 2 | 12.56636 | 12.55 | 12.36* | 12.546 | 12.568 | 12.552 + | | | | | | + 3 | 28.27431 | 28.24 | ...... | ...... | 28.280 | 28.288 + ---------+------------+-----------+--------+--------+--------+-------- + + * Cross bar had to be moved during tracing. + +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. + +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. + +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. + +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: + +6. A practical integraph ought to be easy to read. + +7. Draw a good clear curve. + +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. + +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. + +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. + +2. If P moves along a vertical line, P' does not change, but Q R turns +round it, remaining parallel to O B. + +[Illustration: FIG. 1, 2, 3] + +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 (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. + +It was only when I showed the rough idea of this to 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. + +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." + +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 L14, 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. + +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.e., 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, k0 h being the polar distance. k0 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 k0, 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 k0, which is done by means of a screw in f f at k0, +the chariot, B, can be run down f' f' as nearly opposite to k0 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. + +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. + +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. + +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. + + * * * * * + + +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. + + * * * * * + + + + +SOME HINTS ON SPIKING TRACK. + + +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. + +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 deg. curve, up to about 3/4 in. +on a 12 deg. curve. + +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. + +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. + +[Illustration] + +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. + +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 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.--_J.A. Hall, on Construction and Maintenance +of Track, before American Society of Civil Engineers._ + + * * * * * + + + + +THE EXPERIMENTS AT THE ANNAPOLIS PROVING GROUNDS. + + +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. + +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. + +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. + +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. + +Our engravings show the proving grounds and the details of the +arrangements adopted for backing the plates. + +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. + +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. + +[Illustration] + +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. + +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. + +Each of the plates then received in its center a final blow from this +projectile. + +Our engraving represents the state of the plates after this last shot. + +[Illustration: ARMORED PLATE TESTS AT ANNAPOLIS] + +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. + +In one of our engravings may be seen, too, the state of the shells +after each of the three shots. + +[Illustration] + +The commission immediately and unanimously classified the three plates +in the following order of superiority: (1) Nickel steel; (2) all +steel; (3) compound. + +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.-_L'Illustration._ + + * * * * * + + + + +HIGH EXPLOSIVES IN WARFARE.[1] + +[Footnote 1: A lecture delivered before the Franklin Institute, +Philadelphia, November 28, 1890. From the _Journal_ of the Institute.] + +BY COMMANDER F.M. BARBER, U.S.N. + + +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. + +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. + +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. + +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. + +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 NO2 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. + +The power exerted by these nitro-substitution products is due to the +fact that they detonate, i.e., 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 +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. + +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. + +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. + +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. + +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. + +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. + +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. + +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: + + Blasting gelatine........................... 142 + Forcite " ........................... 133 + Dynamite No. 1.............................. 100 + Gun-cotton, wet............................. 87 + Nitro-glycerine............................. 81 + Gunpowder.............................. 20 to 50 + +Col. Bucknill, of the Royal Engineers, in his publication of 1888, +gives the following: + + Blasting gelatine........................... 142 + Forcite " ........................... 133 + Dynamite No. 1.............................. 100 + Gun-cotton, dry............................. 100 + " " ............................. 80 + Gunpowder................................... 25 + +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.: + + Pounds. + At 5 feet.................................. 4 + " 10 " .................................. 17 + " 20 " .................................. 67 + " 30 " .................................. 160 + " 40 " .................................. 311 + +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. + +His results are as follows: + Pounds. + At 5 feet................................ 231/2 + " 10 " ................................ 75 + " 20 " ................................ 177 + " 30 " ................................ 274 + " 40 " ................................ 369 + +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 _fac-simile_ 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 formulae 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. + +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: + + Nitro-glycerine............................ 1.6 + Blasting gelatine.......................... 1.45 + Forcite " .......................... 1.51 + Dynamite No. 1............................. 1.6 + Wet gun-cotton............................. 1.32 + Dry " ............................. 1.06 + Gunpowder.................................. 0.9 + +Their relative efficiency under water per cubic foot, according to +Bucknill, is as follows: + + Blasting gelatine.......................... 1.38 + Forcite " .......................... 1.27 + Dynamite No. 1............................. 1.00 + Dry gun-cotton............................. 0.66 + Wet " ............................. 0.66 + Gunpowder.................................. 0.14 + +The wet gun-cotton has twenty-five per cent. of added water. + +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. + +Five hundred pounds buoyant gun-cotton mines require 320 feet spacing. + +Five hundred pounds buoyant blasting gelatine mines require 450 feet +spacing. + +Six hundred pounds ground gun-cotton mines require 180 feet spacing. + +Six hundred pounds ground blasting gelatine mines require 230 feet +spacing. + +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. + +A Whitehead was successfully used in the Turco-Russian war of 1877. +The Turkish vessel previously mentioned was sunk by one. + +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: + + (1) Very shattering in its effects. + + (2) Insensible to shocks of projectiles. + + (3) Plastic. + + (4) Easy and safe to manipulate. + + (5) Easy to insert a fuse. + + (6) Great stability at all natural temperatures and when used + in wet localities. + +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. + +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: + + No. 1 dynamite 1.0 + Dry gun-cotton 1.17 + Nitro-glycerine 1.20 + +Powder blew out and could not be measured. + +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-- + + No. 1 dynamite 1.0 + Dry gun-cotton 1.37 + Nitro-glycerine 2.51 + Explosive gelatine 2.57 + Forcite gelatine 2.7 + Warm nitro-glycerine 2.7 + Gunpowder 0.1 + +The powder gave great trouble in this case, also, by blowing out. + +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: + + Meters. + Blasting powder 2.6 + No. 1 dynamite 31.4 + Forcite of 75 per cent. N.G. 43.6 + Blasting gelatine 45.0 + + +Roux and Sarran obtained by experiments in bursting small bomb shells +the following comparative strengths of ranges: + + Powder 1.0 + Gun-cotton 6.5 + Nitro-glycerine 10.0 + +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. + +Chalon gives for quarrying: + + Powder 1 + Dynamite No. 2, containing 50 per cent. nitro-glycerine 3 + +For open blasting: + + Dynamite No. 3, containing 30 per cent. N.G. 1.0 + Dynamite No. 1, containing 75 per cent. N.G. 2.5 + Blasting gelatine 3.5 + +For tunneling: + + Dynamite No. 3, containing 30 per cent. N.G. 1 + Dynamite No. 1, containing 75 per cent. N.G. 3 + Explosive gelatine 19 + +Finally Berthelot's theoretical calculations give a specific pressure +of-- + + Powder 1 + Dynamite 13 + Gun-cotton 14 + Nitro-glycerine 16 + Blasting gelatine 17 + +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: + + Powder 1 + Gun-cotton and dynamite 6 to 10 + Nitro-glycerine 13 to 15 + Blasting gelatine 15 to 17 + +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. + +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. + +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. + +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. + +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). + +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. + +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. + +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. + +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. + +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: + + 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 " + +ARMOR-PIERCING FORGED STEEL SHELL. + + 6-inch, 3 calibers long, weight 100 lb, charge 11/2 lb. + 8 " " " 250 " 3 " +10 " " " 500 " 51/2 " +12 " " " 850 " 11 " + +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 0.4 of an inch thick. +(If they are made thinner, they will swell and jam in the gun when +fired.) + +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. + +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. + +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. + +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. + +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. + +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. + +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. + +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. + +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 deg. 20, with +a ten-inch subcalibered projectile, about 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. + +At elevations below 15 deg. 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. + +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. + +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. + +This same shell, if filled with gunpowder, would have contained but +twenty-five pounds, and have had but one-ninth the power. + +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. + +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. + +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. + +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. + +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. + + * * * * * + + + + +THE MANUFACTURE AND USE OF PLASTER OF PARIS. + + +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. + +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. + +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. + +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 _dead burnt_. 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. + +The view generally adopted with regard to the theory of these +processes is that plaster consists of anhydrous calcium sulphate, +CaSO4, in a condition probably amorphous, different from that of +natural crystallized CaSO4, 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. + +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. + +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. + +The arrangement employed in France is known as the _four a boulanger_, +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.e., before the details +have lost their sharpness. + +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. + +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. + +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 +_dilute_ 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. + +The following explanation of this connection is offered, an +explanation only tentative at present, owing to want of experimental +data. + +The following substances are known: + + Gypsum, and set plaster, CaSO4 + 2 H2O, containing 20.93 + per cent. of water. + + Plaster completely burned at moderate temperature, CaSO4, + probably amorphous. + + Anhydrite and dead-burned plaster, CaSO4, crystalline. + + Selenitic deposit from boilers, 2 CaSO4 + H2O, or CaSO4 + + 1/2 H2O, containing 6.2 per cent. of water. + +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. + +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, e.g., 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 (_vide supra_) 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. + +It will be seen that the dehydration has never passed the composition +corresponding to 2 CaSO4 + H2O; indeed, the material approximates +more nearly to the composition 3 CaSO4 + H2O. 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 H2O, but of a lower hydrate of calcium sulphate. + +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 H2O, which would contain 8.1 per +cent. of water. + +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). + +The method described in the specification consists in reducing the +materials (waste moulds, etc.) to small lumps, and baking between the +temperatures of 95 deg. and 300 deg.. It is mentioned that the whole of the +water must not be expelled. This is no doubt correct, but it must be +effected by regulating the _time_ of baking, since by prolonging the +operation all the water of crystallization can be expelled far below +300 deg.. 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.--_Chem. Trade +Jour._ + + * * * * * + + + + +SPACING THE FRETS ON A BANJO NECK. + +BY PROF. C.W. MACCORD. + + +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. + +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. + +[Illustration: SPACING FOR BANJO FRETS] + +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. + +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. + +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. + + * * * * * + + + + +GLOVE MAKING. + + +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. + +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. + +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. + +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. + +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. + +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. + +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 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. + +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. + +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. + +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. + +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. + +The leathermaker leaves off and the glovemaker begins. + +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. + +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. + +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. + +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.--_The Mercer._ + + * * * * * + + + + +FABRIC FOR UPHOLSTERY PURPOSES. + + +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.--_Jour. of Fabrics._ + +[Illustration] + + * * * * * + + + + +REVERSIBLE INGRAIN OR PRO-BRUSSELS CARPET. + + +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.e., two colors by the weft and four by the ingrain warp, +marked d, d¹, e, and e¹, the warp being so manipulated by the harness +as to make the carpet reversible, and having a corresponding pattern +or figure on both sides.--_Journal of Fabrics._ + +[Illustration: Fig. 1] + +[Illustration: Fig. 2] + +[Illustration: Fig. 3] + + + * * * * * + + + + +ARAEO-PICNOMETER. + + +A modified araeometer 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. + +With the ordinary araeometers, as hitherto constructed, a considerable +quantity of the test fluid is required, and an elaborate calculation +necessary for each determination. In the new araeo-picnometer these +drawbacks are ingeniously avoided, so that the specific gravity of any +liquid can be quickly and easily obtained with astonishing accuracy. + +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. + +[Illustration] + + ^ + = + = + = + = a + = + = + \ = / + | = | + |~~~~~~~~~~~~~~| + | - - = - -| + |- - = - | + | - - = - -| + |- - = - | + | - / \ -| + |- - | b | - | + | \ / -| + |- e//- -\\d | + | - | c | -| + |- \ _ / | + | - \ / -| + |- = - | + | - = -| + |- | | - | + | - \f/ -| + |- - v - | + | -| + / \ + ------------------ + + +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). + +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. + +As the process is an exceedingly simple one and free from the +drawbacks of the araeometer, we are justified in concluding that the +araeo-picnometer will soon be in general use. + +H. HENSOLDT, Ph.D. + +Petrographical Laboratory, School of Mines, Columbia College. + + * * * * * + +[Continued from SUPPLEMENT, No. 793, page 12669.] + + + + +GASEOUS ILLUMINANTS.[1] + +[Footnote: Lectures recently delivered before the Society of Arts, +London. From the _Journal_ of the Society.] + +BY PROF. VIVIAN B LEWES. + + +IV. + +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. + +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. + +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. + +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: + +Carbon. Water. + C + 2H2O = CO2 + 4H2 + +And the carbon dioxide so produced interacts with more red-hot carbon, +forming the lower oxide--carbon monoxide: + + CO2 + C = 2CO + +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: + + WATER GAS. + + Hydrogen 48.31 + Carbon monoxide 35.93 + Carbon dioxide 4.25 + Nitrogen 8.75 + Methane 1.05 + Sulphureted hydrogen 1.20 + Oxygen 0.51 + ------ + 100.00 + +The above is an analysis of water gas made from ordinary gas coke in a +Van Steenbergh generator. + +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. + +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. + +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. + +In considering these methods, we find they can be divided into two +classes: + +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 + +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. + +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. + +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. + +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. + +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. + +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. + +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 +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. + +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. + +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. + +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. + +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 _nil_. + +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. + +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. + +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.e., the quantity of petroleum and the +illuminating value of the gas, have also been checked and corroborated +by Mr. Heisch and Mr. Leicester Greville. + + Total gas made = 8,700 cubic feet. + + Time taken: Blowing. 1 hour. + Time taken: Making. 50 minutes. + + Fuel used: Gas coke. 270 lb. = 31 lb. per 1,000 c.f. + Fuel used: Naphtha, sp. gr. 0.709. 34 gals. = 2.7 gals. per 1,000 c.f. + + Illuminating power of gas = 21.9 candles. + +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. + +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. + +COMPOSITION OF THE GAS. + + Hydrogen. 46.75 + Olefines. 7.59 + Ethane. 6.82 + Methane. 11.27 + Carbon monoxide. 11.65 + Carbon dioxide. 0.50 + Oxygen. 0.17 + Nitrogen. 8.25 + ------- + 100.00 + + +UNPURIFIED GAS CONTAINED + + Carbon dioxide. 2.32 per cent. + Sulphureted hydrogen. 2.84 " + Total sulphur per 100 cu. ft. = 6.67 + Ammonia. nil + Bisulphide of carbon. nil + + Gas produced Naphtha used + Gals. Pts. + 1st. Make. 3,600 cu. ft. 10 7 + 2d. " 2,800 " 7 6 + 3d. " 2,300 " 5 3 + ------ --- -- + 8,700 24 0 + +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. + +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. + +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. + +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 voluntary or involuntary, and by hindering +this, it at once stops life. + +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. + +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. + +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. + +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 _per +se._ 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. + +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. + +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. + +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. + +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. + + Lowe Van Steenbergh + gas. gas. + + Hydrogen..................... 27.14 46.75 + Marsh gas.................... 25.35 11.27 + Carbon monoxide.............. 26.84 18.65 + Illuminants.................. 14.63 7.59 + Ethane....................... ---- 6.82 + Carbon dioxide............... 3.02 0.50 + Oxygen....................... 0.15 0.17 + Nitrogen..................... 2.87 8.25 + ------ ------ + 100.00 100.00 + +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. + +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. + +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: + + American. Russian. + No. of cubic feet per gallon... 72 104 + ---- ---- + Hydrogen....................... 26.0 45.3 + Methane........................ 41.6 22.3 + Ethane......................... 12.5 13.9 + Olefines....................... 14.1 11.6 + Carbon monoxide................ 3.3 3.5 + Carbon dioxide................. 1.7 2.3 + Oxygen......................... 0.8 1.1 + Nitrogen....................... Nil. Nil. + ----- ----- + 100.0 100.0 + +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. + +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: + + Calculated. Actual. + Hydrogen...................... 47.09 42.09 + Methane....................... 5.48 11.27 + Olefines...................... 2.53 7.59 + Ethane........................ 2.17 6.32 + Carbon monoxide............... 30.07 18.65 + Carbon dioxide................ 3.78 2.32 + Oxygen........................ 0.56 0.17 + Nitrogen...................... 7.17 8.25 + Sulphureted hydrogen.......... 1.15 2.84 + ------ ------ + 100.00 100.00 + +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. + +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. + +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. + +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 2.62 d. 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. + +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. + + s. d. + Oil.................................... 1 0 + Coke................................... 0 3 + Labor and purification................. 0 2 + Charge on plant........................ 0 1 + ---- + 1 6 + +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. + +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: + + s. d. + Two and a half gallons of oil........... 0 10 + Thirty pounds of coke................... 0 21/4 + Labor and purification.................. 0 2 + Charge on plant......................... 0 03/4 + ------ + 1 3 + +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. + +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. + +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. + +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. + +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. + +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. + +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. + +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. + +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. + +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. + +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. + +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 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. + +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-- + + Phenol. Benzene. + C6H5HO + C = C6H6 + CO. + +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. + +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. + +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: + +RESULTS OBTAINED ON CRACKING PHENOLOID OIL. + + I. II. III. + + Temperature. 600 deg. C. 800 deg. C. 1,000 deg. C. + Volume of gas per gallon. 41.6 c.f. 76.8 c.f. 121.6 c.f. + +COMPOSITION OF THE GAS. + + Hydrogen. 34.0 36.0 37.0 + Methane. 20.0 26.0 49.0 + Olefines. 11.0 5.0 Nil. + Ethane. 16.0 9.0 Nil. + Carbon monoxide. 13.0 15.0 12.0 + Carbon dioxide. 2.0 4.0 2.0 + Oxygen. 2.0 1.0 Nil. + Nitrogen. 2.0 4.0 Nil. + +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. + +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. + +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. + +(_To be continued_.) + + * * * * * + + + + +ELECTRICAL LABORATORY FOR BEGINNERS. + +BY GEO. M. HOPKINS. + + +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. + +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. + +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? + +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. + +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. + +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. + +[Illustration: FIG. 1.--SIMPLE BATTERY.] + +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. + + +THE SOLUTION. + +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. + +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. + +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. + +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. + + +CONVENTIONAL SIGN FOR THE BATTERY AND GALVANOMETER. + +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: [Illustration] Where more cells +are required, this sign is repeated once for each cell, thus: +[Illustration] The galvanometer is represented thus: [Illustration] + +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. + +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. + +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. + +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. + +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. + +[Illustration] + + +DECOMPOSITION OF WATER. + +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. + +[Illustration: FIG. 3.--DECOMPOSITION OF WATER.] + + +SOLENOID. + +By connecting one of the coils, A, with the battery 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. + +[Illustration: FIG. 4.--SOLENOID.] + + +MAGNETIZATION OF STEEL. + +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. + + +ELECTROMAGNET. + +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. + +[Illustration: FIG. 5.--ELECTROMAGNET.] + + +ELECTRIC MOTOR. + +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. + + +COMPASS AND MAGNETIC EXPERIMENTS. + +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. + +[Illustration: FIG. 7.--MAGNETIC EXPERIMENT.] + + +GALVANOMETER. + +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. + + +EXPERIMENTS SHOWING THE EFFECTS OF RESISTANCE. + +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. + + +RESISTANCE OF A FLUID CHANGED BY THE ADDITION OF ANOTHER FLUID. + +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. + +Common salt added to the water will produce the same effect. + + +MAGNETIC ELECTRIC INDUCTION. + +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. + + +INDUCTION COIL. + +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 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. + +[Illustration: FIG. 11.--MAGNETO-ELECTRIC INDUCTION.] + + +EXTRA CURRENT. + +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. + + +TELEGRAPH SOUNDERS AND KEYS. + +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. + +[Illustration: FIG. 15.--MAGNETIC FIGURES.] + +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. + +Those who desire to practice telegraphy should learn the Morse +telegraphic code. + + +MAGNETIC FIGURES. + +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. + + +EXPERIMENT SHOWING THE CURRENT. + +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. + +[Illustration: FIG. 16.--EXPERIMENT SHOWING THE CURRENT.] + + +MICROPHONE AND TELEPHONE. + +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. + + +ELECTRO METALLURGY. + +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. + + +THE HEATING EFFECT OF THE CURRENT. + +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. + +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. + + +DUPLICATION OF BATTERIES. + +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. + +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. + +It will be found convenient if the elements of the 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. + + * * * * * + + + + +THE ACTION OF THE SILENT DISCHARGE ON CHLORINE. + + +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 _Chemical News_, 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. + +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. + + * * * * * + + + + +ESTIMATING CARBON IN ORGANIC SUBSTANCES. + +BY J. MESSINGER. + + +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. + +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 (CO2) then passes through a U-tube, +in one limb of which is sulphuric acid, in the other glacial +phosphoric acid. + +[Illustration: APPARATUS FOR THE ESTIMATION OF CARBON IN ORGANIC +SUBSTANCES.] + +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. + +With substances containing halogens, it is advisable to place, after +the copper oxide tube, a small washing flask containing potassium +iodide solution. + + * * * * * + + + + +NEW RACE OF DWARF DAHLIAS. + + +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. + +[Illustration: TOM THUMB SINGLE DAHLIAS.] + +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.--_The Gardeners' Magazine_. + + * * * * * + + + + +SOME WINNEBAGO ARTS. + + +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: + +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 _shibboleth_, and found that he could +only say _sibboleth_. A twist of the tongue in pronouncing a word is a +small matter, but, small as it is, it may be perpetuated for ages. + +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 archaeologist finds in the caverns +bones of various mammals, teeth of cave bear, and antlers of reindeer +carved with animal figures. The art is _good_ 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. + +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. + +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 Zuni. 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 _American Antiquarian_, 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 _in intaglio_, +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. + +They are _unique_. 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. + +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. + +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 them directly, to some Dakota stock from which the +Winnebagoes have descended. + +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 _ci-bo-hi-kan_. 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. + +The most beautiful work done on this reservation is the bead weaving +on the ci-bo-hi-kan--woven work, _not_ 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. + +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. + +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, +_Have we here an ethnic survival?_ + +At the close of the paper Dr. Starr exhibited a number of fine +specimens of Indian handiwork, including woven work, bags, belts, etc. + +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. + +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. + + * * * * * + + + + +THE PHILOSOPHY OF CONSUMPTION. + +By Dr. J.S. CHRISTISON, Chicago. + + +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. + +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. + +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. + +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 _pars minoris resistentiae_--a special weakness in a +special way. + +That the germ _bacillus_ 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. + +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. + +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. + + * * * * * + + +THE SCIENTIFIC AMERICAN + +ARCHITECTS AND BUILDERS EDITION. + +$2.50 a Year. Single Copies, 25 cts. + +This is a Special Edition of the SCIENTIFIC AMERICAN, issued +monthly--on the first day of the month. Each number contains about +forty large quarto pages, equal to about two hundred ordinary book +pages, forming, practically, a large and splendid Magazine Of +Architecture, richly adorned with _elegant plates in colors_ and with +fine engravings, illustrating the most interesting examples of modern +Architectural Construction and allied subjects. + +A special feature is the presentation in each number of a variety of +the latest and best plans for private residences, city and country, +including those of very moderate cost as well as the more expensive. +Drawings in perspective and in color are given, together with full +Plans, Specifications, Costs, Bills of Estimate, and Sheets of +Details. + +No other building paper contains so many plans, details, and +specifications regularly presented as the SCIENTIFIC AMERICAN. +Hundreds of dwellings have already been erected on the various plans +we have issued during the past year, and many others are in process of +construction. + +Architects, Builders, and Owners will find this work valuable in +furnishing fresh and useful suggestions. 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