A PARADOXICAL ANARCHIST.By Prof. CESARE LOMBROSO.

Smokeless Powders.In the bottle is indurite in flake grains. The larger grains are cylindrical and hexagonal multiperforated United States army grains. The bent grain in the foreground, looking like a piece of rubber tubing, is a grain of Maxim powder with a single canal. The flat strips in the foreground on the left are grains of the French B. N. powder. The flat strips in the foreground on the right are grains of the United States navy “pyrocellulose” powder.

Mercury fulminate is made by dissolving mercury in nitric acid and pouring the solution thus produced into alcohol, when a violent reaction takes place and the fulminate is deposited as a crystalline gray powder. This powder is loaded in copper cases and, after drying, it is primed with dry-mealed gun cotton, the mouth of the case being closed with a sulphur-glass plug, through which pass two copper leading wires joined by a bridge of platinum-iridium wire, two one-thousandths of an inch in diameter,which becomes heated to incandescence when an electric current is sent through it. This device is what is known as the naval detonator. Mercury fulminate is so employed because it is the most violent of all explosives in common use, and exerts a pressure of forty-eight thousand atmospheres when fired in contact. Although the naval detonator contains but thirty-five grains of mercury fulminate, yet it will rupture stout iron and heavy tin torpedo cases when fired suspended in them, it will rend thick blocks of wood when placed in a hole and fired within them, and it will even pierce holes through plates of the finest wrought iron one-sixteenth inch in thickness if only the base of the detonator is in contact with the plate, and this has been used as a test of their efficiency. Its force is markedly shown by firing one in a stout iron cylinder filled with water and closed tightly, when the cylinder is blown into a shredded sphere. When used to detonate gun cotton, either when confined or in the open, the detonator is placed in the hole which has been molded in the center of the gun cotton disk or block, so that it shall be in close contact with the gun cotton. I have found that perfectly dry compressed gun cotton is detonated by 2.83 grains of mercury fulminate; but as a torpedo attack is necessarily in the nature of a forlorn hope and should be provided with every possible provision against failure, and since if the detonator fails the attack fails, the naval detonator is supplied with thirty-five grains, so as to give a large coefficient of assurance.

Blending Machine for Cordite.

Cartridge of Cordite Smokeless Powder.Charge for 6-inch 2 F gun, 13 pounds, 4 ounces. Cords, 22¾ inches long, 3 inches in diameter.

A characteristic feature of gun cotton is that it may be detonated even when completely saturated with and immersed in water, if only some dry gun cotton be detonated in contact with it. Thus in one experiment a disk of dry gun cotton was covered with a water-proof coating and the detonator inserted in the detonator hole of this disk. This dry disk was laid upon four uncoated disks, the five lashed tightly together, and sunk in Newport Harbor, where the column remained until the uncoated disks were saturated with salt water, when the mine was fired and the saturated disks were found by measurement of the work done to have been completely exploded. I have found that three ounces of dry compressed gun cotton will cause the detonation of wet compressed gun cotton in contact with it, but forty ounces of dry gun cotton are used as the primer in our naval mines and torpedoes, so as to give a large coefficient of assurance.

Gun-Cotton Spar Torpedo.

Blowing up the Schooner Joseph Henry.

In the mining and other industries the fulminate is used in smaller quantities and it is generally mixed with potassium chlorate, the mixture being compressed in small copper cases and sold as blasting caps. They are fired by means of a piece of Bickford or running fuse, consisting of a woven cotton or hemp tube containing a core of gunpowder, which is inserted in the mouth of the copper cap and made fast within it by crimping. The capped fuse is then inserted in a dynamite cartridge so that the cap is firmly in contact with the dynamite, the mouth of the cartridge is fastened securely, and the charge inserted in the bore-hole in the rock and tamped. The protruding end of the fuse is lighted, and the fire travels at the rate of three feet per minutedown the train of gunpowder to the fulminate, which then detonates and causes the detonation of the dynamite.

Although gun cotton, nitroglycerin, and their congeners can be and usually are fired by detonation, there has within recent years been a great number of compositions invented which, while formed from gun cotton alone or mixtures of it with nitroglycerin, burn progressively when ignited and are therefore available for use as propellants; and since the products of their burning are almost wholly gaseous, they produce but little or no smoke and are therefore called smokeless powders. As upward of fifty-seven per cent of the products of the burning of ordinary gunpowder are solids or easily compressed vapors, this comparative smokelessness of the modern powders is a very important characteristic, and when used in battle they seriously modify our former accepted methods of handling troops. While this is the feature of these powders which has attracted popular attention, a far more important quality which they possess is the power to impart to a projectile a much higher velocity than black powder does, without exerting an undue pressure on the gun. A velocity of over twenty-four hundred feet per second has been imparted to a one-hundred-pound projectile with the powder that I have invented for our navy, while the pressure on the gun was less than fifteen tons to the square inch.

Torpedo Practice.Bow discharge.

Prior to my work in this field all the so-called smokeless powders were mixtures of several ingredients, resembling gunpowder in this respect. But, considering the precise and difficult work that was expected of these high-powered powders and the difficultywhich had always been found in securing uniformity in mixtures, and that this difficulty had become the more apparent as the gun became more highly developed, I sought to produce a powder which should consist of a single chemical substance in a state of chemical purity, and which could be formed into grains of such form and size as were most suitable for the piece in which the powder was to be used.

I succeeded in so treating cellulose nitrate of the highest degree of nitration as to convert it into a mass like ivory and yet leave it pure. In this indurated condition the gun cotton will burn freely, but it has not been possible to detonate it even when closely confined and exposed to the initial detonation of large masses of mercury fulminate.

Torpedo Practice on the Cushing.Broadside discharge.

I am happy to say that this principle has now been adopted by the Russian Government, and by our navy in its specifications for smokeless powder; but they have, I think unwisely, selected a cellulose nitrate containing 12.5 per cent or less of nitrogen instead of that of the highest nitration.

This work was completed, a factory established, and the processes well marked out when I left the torpedo station in 1892. Besides this, there were then already commercial works established elsewhere in this country for the manufacture of the nitroglycerin-nitrocellulose powders of the ballistite class, while large quantities of many varieties could be easily procured abroad. Considering these facts, and that France and Germany had already adopted smokeless powders in 1887, that Italy adopted one in 1888, and England about the same time, it is unpardonable that our services should not yet have adopted any of the smokeless powders available when we were drawn into the conflict with Spain.

Besides their use as ballistic agents, gun cotton, dynamite, and explosive gelatin in their ordinary condition have found employment and been adopted as service explosives in military and naval mining, as their great energy and the violence with which they explode, even when unconfined, especially adapt them for use in the various kinds of torpedoes and mines which are in vogue in the service.

Launching Patrick Torpedo from the Ways.

One form of these torpedoes was attached to the end of a spar or pole which was rigged out from the bow of a launch or vessel so that it could be thrust under the enemy’s vessel, and the detonators of such spar torpedoes were not only connected with electric generators, so that they could be fired at will, but they, in common with mines, were frequently provided with a system of levers so arranged that the enemy’s vessel fired the torpedoes and mines automatically as it came in contact with the levers. It was with such a contact-spar torpedo, containing thirty-three pounds of gun cotton, that the schooner Joseph Henry was blown up in Newport Harbor in 1884.

Patrick Torpedo under way.Moving at the rate of twenty-three knots per hour.

There are many types of the automobile torpedo. Among them the Hall, Patrick, Whitehead, and Howell may be cited.The first three are propelled by the energy resident in compressed gases; the Howell by the energy stored in a heavy fly wheel, which also, by acting on the gyroscopic principle, serves to maintain the direction imparted to the torpedo as it is launched. The Hall, Whitehead, and Howell are launched from tubes or guns by means of light powder charges, and are independent of exterior control after launching. The Patrick is launched from ways, and is controlled from the shore or boat by a wire through which an electric current may be sent to its steering mechanism. The charges are quite variable, but the war heads of the larger torpedoes contain as much as five hundred pounds of gun cotton.

[To be concluded.]

WhileI have had the privilege of making several indirect studies of anarchists by means of the data furnished by legal processes, the journals, and the handwriting of the subjects, I have only rarely been able to examine one directly and make those measurements and craniological determinations upon him without which any study can be only approximate, or, we might even say, hypothetical. I had, however, an opportunity a short time ago to observe a real anarchist in person, and study him according to the methods of my criminological clinic. The results have been singular, and it seems to me that they should cast some light upon the dark world of these agitators, and especially upon the phenomena of the strange contradictions presented in their life; manifestations which jurists and police officers, intent only on achieving the judicial triumph of a conviction, consider and call simulations and falsehoods.

(Unclear handwritten inscription)

He was a fellow who had caused a great excitement, during the crowded days of the exposition at Turin, by saying that he wanted to kill the king. In fact, he gave himself up to the police, saying that the anarchists of Alexandria were seeking the assassination of the king, and had written him a letter directing him to arm himself, but that he, wishing anything else than to commit regicide, had surrendered in order to denounce the scheme. There was no real basis of criminal intent, but our police put him in prison, and there I found him.

His physiognomy presented all the characteristics of the born criminal and of the foolhardy and sanguinary anarchist. He hadflaring ears, premature and deep wrinkles, small, sinister eyes sunk back in their orbits, a hollowed flat nose, and small beard—in short, he presented an extraordinary resemblance to Ravachol, as may be seen from their portraits.

The cranium was a little smaller than the normal, and the upper part of the skull was much rounded and deformed, with a cephalic index of 91—considerably more rounded than the head of Luccheni. The horizontal fold of the hand was of a type much like that of Ravachol.

I add that the biological study, which was made directly, and therefore more satisfactorily than was practicable with Caserio and Luccheni, revealed a series of very singular anomalies; a touch six times more obtuse than the normal—six millimetres on the right, five on the left; a remarkably blunt sensitiveness to pain and dull perception of location; an extraordinarily reduced visual field, particularly in the left eye; a somewhat tremulous handwriting, and slight defects of articulation in speech; and thin hair. There was nothing very striking in his affective nature. He spoke kindly of his parents, whom he would be glad to see. But he had a blunt moral sense, and had committed frequent thefts, especially against his family, so that he had been put into a house of correction. And it was just while he was still in this establishment, at sixteen years of age, that he pretended to have been invited to attend a meeting of about thirty anarchists at Brescia, where he was made to swear, kissing a dagger, to kill the king. He described the room, and spoke of the individual persons present, and then said that he thought no more of the matter after he returned to the house; but a few days ago it had come into his mind to go to the post office, and there he had found a letter from the anarchists of Alexandria, urging him to arm himself to kill the king.

He repeated this story minutely and with great persistence, notwithstanding the postal authorities denied having given him the letter, in the face of the asseverations of the prefects that there were not thirty anarchists in Brescia, where he was in correction, and although all the facts were against him. Observe that he was in prison, that he had been there three months, and that he was told he would be likely to stay there as long as he adhered to his story.

Ravachol.

Efforts to account for the phenomenon were unsuccessful, because his friends and relatives made no mention of any traces of insanity. Light began to break upon the case when it was learned that he had attempted suicide, a few years before, in grief at the death of his mother, and also that on the day before he gave himself up he had stolen a small sum from his drunken brother. These, however, were only distant hints. The matter was fully explained when, after he had drunk a litre of wine in the prison, he began to exclaim, “Viva l’anarchio!” (Hurrah for anarchy!), “Morte al Re!” (Death to the king!), to kiss a dagger, to break various things against imaginary guards, and, after a short period of quiet, to swear and forswear himself that his companions had done what he had done, that they had shouted for anarchy, had broken the vases, and had desired to kill the king.

Visual Field (Left Eye) of Chie ... Giac ...The thin line indicates the normal visual field (left eye).The thick line indicates the visual field (left eye) under alcoholic excitement.

Visual Field (Left Eye) of Chie ... Giac ...

The thin line indicates the normal visual field (left eye).The thick line indicates the visual field (left eye) under alcoholic excitement.

The thin line indicates the normal visual field (left eye).

The thick line indicates the visual field (left eye) under alcoholic excitement.

This cleared up the matter at once for me, but I wished to complete the elucidation with an experiment. I began by giving him ten, then twenty, then thirty, then forty grammes of alcohol, up to eighty. I observed that his personality began to change after forty grammes. He became somewhat insolent and suspicious, and had vague delirious imaginings of persecutions. When invited to sing anarchistic songs he refused, evidently fearing to compromise himself, but sang them voluntarily in an undertone. When the dose of alcohol was increased to ninety grammes his personality seemed immediately to undergo a full change; his touch became twice as fine (three millimetres), and his visual field increased threefold; he declared that there was a spy around. When put into his cell he sang anarchistic hymns, threatened death tothe king, handled a box as if brandishing a dagger, climbed to a window and insulted the sentinel, resisted five men who tried to disarm him, and continued in this condition for eight hours.

The next day he denied having done any of these things, avowed that he was a good monarchist and a good citizen, and declared distinctly that he had not done what he had done, in the face of the concurrent testimony of several witnesses. On renewing the experiment a few days afterward with eighty grammes of alcohol, the same series of phenomena recurred—a real anarchistic raving, a genuine mania for regicide, which would certainly have ended in some act if he had not been restrained by force; and this person, who had at first presented an evident obtusity of touch and an extraordinary contraction of the visual field, now exhibited an almost normal touch of three millimetres and a visual field enlarged to triple its extent when he was sober.

On the day after this he recollected none of all the things that had happened the day before. This double personality was determined in him by alcohol, as it is in others by misery or by fanaticism, while it rests with all upon a congenital basis. The fact helps us to explain how some inoffensive man may have a type of physiognomy quite similar to that of Ravachol, showing how often there are true criminals in potency, whose physiognomy, or rather the anomalies of it, bears a prophetic relation to the crime which breaks out on the first determining circumstance. And we have here another explanation of such contradictory characters as those of Ravachol, Caserio, and Luccheni, who, having been once well-behaved, end by becoming criminals.

Applied science was defined by Sir W. Roberts Austen, in his presidential address to the Iron and Steel Institute, 1899, as “nothing but the application of pure science to particular classes of problems.”

Ofall the wonderful operations accomplished by the aid of electricity at the present time, none so completely mystifies the beholder as the action of the trolley car. The electric light, although incomprehensible to the average layman, does not excite his curiosity to the same extent. The glowing filament of an incandescent lamp or the dazzling carbon points of an arc light stimulate the inquisitive proclivities to some extent, but as the popular notion with respect to the nature of electricity is that it is some kind of fluid that can flow through wires and other things like water through a pipe, the conclusion arrived at is that the current, in its passage through the filament or the carbon points, generates a sufficient amount of heat to raise the temperature of the material to the luminous point. The fact that energy is required to raise the temperature of the mass to the incandescent point is not taken into consideration by those not versed in technical matters, owing to the fact that, as nothing moves, it is not supposed that power can be expended. When a trolley car is seen coming down the street at a high rate of speed the effect upon the mind is very different. Here we see a vast amount of weight propelled at a high velocity, and yet the only source through which the power to accomplish this result is supplied is a small wire. The mystifying cause does not stop here, for if we look further into the matter we see that the energy has to pass from the trolley wire to the car through the very small contact between it and the trolley wheel. After contemplating these facts, it appears remarkable that the energy that can creep through this diminutive passage can by any means be made to develop the force necessary to propel a car with a heavy load up a steep grade. An electrical engineer, if asked to explain the action, would say that the force of magnetic attraction was made use of to accomplish the result, but this explanation would fail to throw any light upon the subject. In what follows, it is proposed to explain the matter in a simple manner, and then it will be seen that what appears to be an incomprehensible mystery, when not understood, is, in fact, no mystery at all.

Note.—The illustrations of railway motor, generator, and switchboard (Figs. 15,16,17) were made from photographs kindly furnished by the manufacturers, the Westinghouse Electric and Manufacturing Company.

Electricity and magnetism are two forces that are intimately associated with each other, and, although radically different, it isdifficult, if not impossible, to obtain one without the other, although it is a simple matter to make one inactive under certain conditions. It is very generally understood that a magnet possesses the power of attraction, and that it will draw toward it pieces of iron, steel, and other magnets. The laws governing the attractive properties of magnets, however, are not so well understood, and many are not aware of the fact that under certain conditions one magnet will repel another, but such is nevertheless the case.

Figs. 1, 2, 3.—Diagrams illustrating the Attraction and Repulsion of Magnets.

InFig. 1the lower outline,M, represents a magnet fixed in position, and the upper bar represents another magnet arranged to swing freely around the pivota. A magnet, as is generally known, will arrange itself in a north-to-south position if suspended from its center, like a scale beam, and allowed to swing freely, and the same end will always point toward the north. On this account the ends of a magnet are called its poles, and the one that will point toward the north is designated the north pole, while the other one is the south pole. The terms north and south poles were applied to magnets centuries ago, but at the present time the ends are more commonly designated as positive and negative. InFig. 1it will be noticed that the stationary magnet has its positive end upward, and this attracts the negative end of the swinging magnet. If the order of the poles is reversed, so that the positive of the swinging magnet will come opposite the positive of the stationary one, then there will be a repulsive action instead of an attraction, as is shown inFig. 2. If the two negative ends were placed opposite, the effect would be the same. From this we see that to obtain an attraction we must place the magnets so that opposite poles come together, and that by reversing the order we obtain a repulsive action.

If the swinging magnet is replaced by a bar of iron, as is shown inFig. 3, there will be an attraction, no matter what end of the magnet may be uppermost, thus showing that either end of a magnet will attract a bar of iron. The explanation of these different actions is that when two magnets are brought into proximity to each other each one exerts its force without any regard to the other, and if the two are set to act together they will attract one another, but if set to act in opposition they will repel. When one of the bars is not a magnet, but simply a piece of iron or steel,this bar, having no attractive or repulsive force of its own, can only obey the attractive action of the other, which is the only one that exerts a force.

Figs 4, 5.—Diagrams illustrating the Method of obtaining Rotary Motion with Magnets.

InFig. 4Mis a magnet bent into the form of a U, commonly called a horseshoe magnet. The short bar set between the upper ends is also a magnet, and is arranged so as to revolve around the shafts. From what has just been explained in connection withFigs. 1 and 2it will be understood that, with the poles as indicated by the letters, there will be an attractive force set up between the top end of the straight bar and thePend of the horseshoe, and thus rotation will be produced in the direction of the arrow. The rotation, however, will necessarily stop when the bar reaches the position shown inFig. 5, for then the attraction between the poles will resist further movement. If the straight bar were not a magnet, but simply a piece of iron or steel, it is evident that when in the position ofFig. 4the attraction would be just as much toward the right as toward the left, and if the bar were placed accurately in the central position it would not swing in either direction. It would be in the condition called, in mechanics, unstable equilibrium. In practice this condition could not be very well realized, as it would be difficult to set and retain the bar in a position where the attraction from both sides would be the same, therefore the rotation would be in one direction or the other; but whichever way the bar might move, it would only swing through one quarter of a revolution, into the horizontal position ofFig. 5.

If we reflect upon these actions we can see that if we could destroy the magnetism of both parts before the straight bar reaches the position ofFig. 5it would be possible to obtain rotation through a greater distance than one quarter of a turn, for then the headway acquired by the rotating part would cause it to continue its motion. If, after the completion of one half of a revolution, we could remagnetize both parts, we would then set up an attraction between the lower end of the straight bar and the left side of the horseshoe, for then the polarity of the former would be the reverse of that shown inFig. 4—that is, the lower end would be negative. By means of this second attraction we would cause the bar to rotate through the third quarter of the revolution, and if, just beforecompleting this last quarter, we were to remove all the magnetism again, the headway would keep up the motion through the final quarter of the revolution, thus completing one full turn. From this it will be realized that if we could magnetize and demagnetize the two parts twice in each revolution a continuous rotation could be obtained.

If the magnetizing and demagnetizing action were only applied to the rotating part we would fail to keep up a continuous rotation, for, as was shown in connection withFig. 3, the action when the straight bar reached the position ofFig. 5would be the same as if it were magnetized, owing to the fact that a magnet always exerts an attraction upon a mass of iron. Suppose, however, that we were to reverse the polarity of the rotating part just as it reaches the position ofFig. 5, then there would be two poles of the same polarity opposite each other, and, as shown inFig. 2, the force acting between them would be repulsive, and would push the bar around in the direction of rotation. Not only would the right-side pole of the horseshoe force the end of the bar away from it, but the negative pole, on the left side, would attract this same end, and thus a force would be exerted by the two poles ofMto keep up the rotation through the next half of a circle. On reaching this last position the rotation would stop if the polarity of the revolving bar were left unchanged, for then the poles facing each other would be of opposite polarity. If, however, we again reversed the polarity, a repulsion would be set up between the poles facing each other, and thus a force would be exerted to continue the rotation. Thus we see that if the polarity of the horseshoe magnet is not disturbed it is necessary to reverse that of the rotating part to obtain a continuous motion, but if we change the magnetic conditions of both parts, then it is only necessary to magnetize and demagnetize them alternately.

From the foregoing it is seen that there are two ways in which the force of magnetism could be utilized to keep up a continuous rotation, and the question now is, Can either of them be made available in practice? To this we answer that, by the aid of the relations existing between electricity and magnetism, both can be and are made available, as will be shown in the following paragraphs:

Figs. 6, 7, 8.—Diagrams illustrating the Principles of Electro-Magnets.

InFig. 6Wrepresents a coil of wire provided with a cotton covering, so that there may be no actual contact between the adjoining convolutions. If the endsp nof this coil are connected with a source of electric energy, an electric current will flow through it, and if a bar, as indicated byN P, of iron or steel is placed within the coil it will become magnetized. If the bar ismade of steel and is hardened it will retain the magnetism, and become what is called a permanent magnet; such a magnet, in fact, as we have considered in all the previous figures. If the bar is made of iron it will not retain the magnetism, but will only be a magnet as long as the electric current flows through the coilW. A magnet of the latter type is called an electro-magnet. If the iron is of poor quality—that is, from an electrical standpoint—it will require an appreciable time to lose its magnetism, but if it is soft and high grade, electrically considered, it will lose its magnetism instantly, or nearly so. If we take two bars of soft iron and arrange them side by side, as inFig. 7, and wind coils around them as indicated each one will become magnetized when the endsp nof the coils are connected with an electric circuit. If the lower ends of the two bars are joined by a piece, as shown atM, we will have a horseshoe electro-magnet. If we take a round disk of iron, as inFig. 8, and wind a coil around it, it will also become a magnet when an electric current traverses the coil. Thus it will be seen that it makes little difference what the shape of the iron may be, providing it is surrounded by a coil of wire and an electric current is passed through the latter. This being the case, it is evident that either of the processes explained in connection withFigs. 4 and 5can be made available for the production of a continuous rotation by the aid of electro-magnets. Suppose we make a drum, as shown inFig. 9, and wind a wire coil around it in the direction indicated, then when a current passes through the wire the drum will be magnetized, with poles at top and bottom. If the electric current passes through the wire from endpto endnthe drum will be magnetized positively at the top and negatively at the bottom, and if the direction of the current through the wire is reversed the polarity of the drum will be reversed. If we construct a horseshoe magnet of the shape shown inFig. 10, and place within the circular opening between its ends the drum ofFig. 9, we will have a device that is capable of developing a continuous rotation, providing we have suitable means for reversing the direction of the electric current through the wire coil; and this machine constitutes an electric motor in its simplest form.

Figs. 9, 10.—Diagrams illustrating the Principles of the Electric Motor.

In an electric motor the horseshoe magnet is called the fieldmagnet, and the rotating part is called the armature, while the device by means of which the direction of the current through the armature coil is reversed is called the commutator. In this last figure it will be noticed that the coils wound upon the field magnet are represented as of wire much finer than that wound upon the armature. In actual practice machines are sometimes wound in this way, and sometimes the field wire is twice as large as that on the armature. When the field wire is very much finer than that of the armature the machine is what is known as shunt wound, which means that only a small portion of the current that passed through the armature passes through the field coils. Although with this type of winding the current that passes through the field coils is very weak, the magnetism developed thereby can be made greater than that of the armature if desired. This result is accomplished by increasing the number of turns of wire in the field coils. Thus if the current through the armature is one hundred times as strong as that through the field coils, the latter can be made to equal the effect of the former by increasing the number of turns in the proportion of one hundred to one, and if the increase is still greater the field coils will develop the strongest magnetism. The reason why a small current passing around a magnet a great many times will develop as strong a magnetization as a large current, can be readily understood when we say that the magnetism is in proportion to the total strength of the electric current that circulates around the magnet. Suppose we have two currents, one of which is one thousand times as strong as the other, then if the weak one is passed through a coil consisting of one thousand turns it will develop just as strong a magnetization as the large current passingthrough a coil of only one turn. This last explanation enables us to see how it is that the comparatively small current that can pass through the contact between the trolley wire and the trolley wheel can develop in the motor force sufficient to propel a heavy car up a steep grade. When that small current reaches the car motors it passes through a thousand or more turns of wire, and thus its effect is increased a corresponding number of times.

A motor having a single coil of wire upon the armature, as inFig. 10, would not give very satisfactory results, owing to the fact that the rotative force developed by it would not be uniform. Such motors are made in very small sizes, but never when a machine of any capacity is required. For large machines it is necessary to wind the armature with a number of coils, so that the rotating force may be uniform, and also so that the current may be reversed by the commutator without producing sparks so large as to destroy the device. When an armature is wound with a number of coils the direction of the current is reversed, by the commutator, in each coil as it reaches the point where its usefulness ends, and where, if it continued to flow in the same direction, it would act to hold the armature back. The effect of this reversal of the current in one coil after another is to maintain the polarity of the armature practically at the same point, so that the strongest pull is exerted between it and the field magnet poles at all times. To explain clearly the way in which the commutator reverses the current in one coil at a time it will be necessary to make use of a diagram illustrating what is called a ring armature. Such a diagram is shown inFig. 11. The ringAis the armature core, and is made of iron; the wire coils are represented as consisting of one turn to each coil, and are markedw w w. The current enters the wire through the springB, and passes out throughC. As can be seen, the current fromBcan flow through the coilsw win both directions, thus dividing into two currents, each one of which will traverse one half of the wire wound upon the armature. The two half currents will meet atC. If the armature is rotated the springsBandC(which are called commutator brushes) will pass from one turn of the wire coil to another just back of it as the rotation progresses, and each time that contact is made with a new turn the direction of the current in the turn just ahead will be reversed. The current in the wire as a whole, however, will always be in the same direction—that is, in all the turns to the right of the two brushes; the current will flow toward the center of the shaft on the front side of the armature, and away from the shaft in all the turns on the left side. As the direction of the current on opposite sides of the brushes is always the same, the polesof the armature will remain underBandC, therefore the relation between the position of the poles of the armature and the field magnet will be the same substantially as that illustrated inFig. 10, and, as a result, the force tending to produce rotation will at all times be the greatest possible for the strength of the current used and the size of the magnets.

Armatures are wound with a number of turns of wire in each coil, unless the machine is very large, and present an appearance more likeFig. 12. In this figure the brushes are arranged to make contact with the outer surface of the ringC, which is the commutator. The segmentss sare connected with the ends of the armature coilsc c c, but are separated from each other by some kind of material that will not conduct electricity—that is, they are electrically insulated. As will be noticed from this, the armature inFig. 11acts as a commutator as well as an armature, its outer surface performing the former office. In the winding the difference betweenFigs. 11 and 12is simply in the number of turns in each coil, there being one turn inFig. 11and several inFig. 12.

Figs. 11, 12.—Diagrams illustrating the Method of winding Armatures of Electric Motors and Generators.

The armature shown inFig. 10is of the type called drum armature, but it can be wound so as to produce the same result as the ring, although it is not so easy to explain this style of winding. It will be sufficient for the present explanation to say that whatever type of armature may be used, the winding is always such that the direction of the current through the wire coils is reversed progressively, so that the magnetic polarity is maintained practically at the same point; therefore there is a continuous pull between this point of the armature core and the poles of the field magnet. The commutator is secured to the armature shaft, and the brushesthrough which the current enters and leaves are held stationary; keeping this fact in mind, it can be seen at once that inFig. 12the current will flow from the brushathrough the two sides of the armature wire to brushb, hence all the coils on the right of the vertical line will be traversed by the current in the same direction—that is, either to or from the center of the shaft—and in the coils on the left the direction will be opposite, which is just the same order as was explained in connection withFig. 11.

Figs. 13, 14.—Diagrams illustrating the Difference between an Electric Motor and a Generator.

An electric motor can be turned into an electric generator by simply reversing the direction in which the armature rotates—that is, any electric machine is either a generator or a motor. This fact can be illustrated by means ofFigs. 13 and 14, both of which show the armature and the poles of the field magnet. The first figure represents an electric motor, and, as can be seen, the pull between theNpole of the armature and thePpole of the field is in the direction of arrowb, hence the armature will rotate in the same direction, as indicated by arrowa. To obtain the polarity of the armature and field it is necessary to pass an electric current through both—that is to say, we must expend electrical energy to obtain power from the machine. As soon as the current ceases to flow, the polarity of the armature and field dies out, and the rotation of the former comes to an end. The magnetism, however, does not die out entirely; a small residue is always left, although it is never sufficient to produce rotation, and even if it were it could only cause the armature to revolve through one quarter of a turn. If, after the current has been shut off, the armature shaft is rotated in the reverse direction, as indicated by arrowainFig. 14, the motion will be against the pull of the magnetism; therefore, although the poles may be very weak, an amount of power sufficient to overcome their attraction must be applied to the pulley, otherwise rotation can not be accomplished. In consequence of the backward rotation a current is generated in the armature coils, and this current, as it traverses the field coils as well as those of the armature, causes the polarity of both parts to increase. As a result of the increased polarity the resistance to rotation is increased, and more power has to be applied to the pulley. The increase in the strength of the poles results in increasing the current generated, and this in turn further increases the pole strength, so that one effect helps the other, the result beingthat the current, which starts with an infinitesimal strength, soon rises to the maximum capacity of the machine.

The motor shown inFig. 10does not in any way resemble an electric railway motor, nevertheless the principle of action is precisely the same in both. The design of a machine of any kind has to conform to the practical requirements, and this is true of railway motors, just as it is true of printing presses, sawmills, or any other mechanism. A railway motor must be designed to run at a comparatively slow speed and to develop a strong rotative force, or torque, as it is technically called. It must also be so constructed that it will not be injured if covered with mud and water. It must be compact, strong, and light, and capable of withstanding a severe strain without giving out. To render the machine water- and mud-proof it is formed with an outer iron shell, which entirely incases the internal parts. The first railway motors were not inclosed, and the result was that they frequently came to grief from the effects of a shower of mud. When the modern inclosed type of motor, which is called the iron-clad type, first made its appearance it was frequently spoken of as the clam-shell type, and the name is not altogether inappropriate, for while the outside may be covered with mud to such an extent as to entirely obliterate the design, the interior will remain perfectly clean and dry, and therefore its effectiveness will not be impaired.

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