The telephone is also used with success in warfare, and in fact sometimes assists the telegraph in cases where, by reason of the haste with which a line has been run, the current leaks off. A telephone may then be used to receive the message - and for a transmitter a simple buzzer or automatic circuit breaker, controlled by an ordinary key. In the case of vessels there is much difficulty in using the telegraph and the telephone, as the wire may be fouled and broken when the ship swings by a long chain. In England in the case of a lightship this difficulty has been surmounted, or rather avoided, by making hollow the cable by which the ship rides, and running an insulated wire along the long tube thus formed inside. But the problem is much simplified when temporary communication only is desired between ships at anchor, between a ship and the shore, or even between a ship and a boat which has been sent off on some special service, such as reconnoitering, sounding, etc. In this case portable telephones are used, in which the wire is so placed on a reel in circuit with the telephone that communication is preserved, even while the wire is running off the reel.

The telegraph and telephone are both coming largely into use in artillery experiments, for example, in tracking a vessel as she comes up a channel so that her exact position at each instant may be known, and in determining the spot of fall of a projectile. In getting the time of flight of projectiles electricity is of value; by breaking a wire in circuit with a chronograph, the precise instant of start to within a thousandth of a second being automatically registered. Velocimeters are a familiar application of electricity somewhat analogous. In these, wires are cut by the projectile at different points in its flight, and the breaking of the electric current causes the appearance of marks on a surface moving along at a known speed. The velocity of the projectile in going from one wire to another can then be found.

Electricity is also used for firing great guns, both in ships and forts. In the former, it eliminates the factor of change produced by the rolling of the ship during the movement of the arm to fire the gun. The touch of a button accomplishes the same thing almost instantaneously. Moreover, an absolutely simultaneous broadside can be delivered by electricity. The officer discharges the guns from a fighting tower, whither the wires lead, and the men can at once lie down out of the enemy's machine guns, as soon as their own guns are ready for discharge. The electric motor will certainly be used very generally for handling ordnance on board ships not very heavily plated with armor, since a small wire is a much more convenient mode of conveying energy to a motor of any kind, and is much less liable to injury, than a comparatively large pipe for conveying steam, compressed air, or water under pressure. Besides, the electric motor is the ideal engine for work on shipboard, by reason of its smooth and silent motion, its freedom from dirt and grease, the readiness with which it can be started, stopped, and reversed, and its high efficiency.

Indeed, in future we may look to a protected apparatus for all such uses in every fort and every powerful ship.

In photographing the bores of great guns, electric lights are used, and they make known if the gun is accurately rifled and how it is standing the erosion of the powder gases.

In the case of a fort, electricity can be employed in connection with the instruments used for determining at each instant the position of an approaching vessel or army. Whitehead torpedoes are now so arranged that they can be ejected by pressing an electric button.

Electric lights for vessels are now of recognized importance. At first they were objected to on the ground that if the wire carrying the current should be shot away in action, the whole ship would be plunged in darkness; and so it would be in an accident befalling the dynamo that generates the current. The criticism is sensible, but the answer is that different circuits must be arranged for different parts of the ship, and the wires carrying the current must be arranged in duplicate. It is also easy to repair a break in a copper wire if shot away. As to the dynamo and engines, they must be placed below the water line, under a protective deck, and this should be provided for in building the vessel. There should be several dynamos and engines. All the dynamos should, of course, be of the same electromotive force, and feed into the same mains, from which all lamps draw their supply, and which are fed by feeders from the dynamo at different points, so that accident to the mains in one part of the ship will affect that part only. But it is the arc light, used as what is called a search light, that is most valuable in warfare. Lieut. Fiske thinks its first use was by the French in the siege of Paris, to discover the operations of the besiegers.

It can be carried by an army in the field, and used for examining unknown ground at night, searching for wounded on the battle field, and so on. On fighting vessels the search light is useful in disclosing the attack of torpedo boats or of hostile ships, in bringing out clearly the target for guns, and in puzzling an enemy by involving him successively in dazzling light and total darkness. Lieut. Fiske suggests that this use would be equally effective in embarrassing troops groping to the attack of a fort at night by sudden alternations of blinding light and paralyzing darkness. There should be four search lights on each side of a ship.

As to the power and beauty of the search light, Lieut. Fiske refers to the magnificent one with which he lighted up Philadelphia last autumn, during the electric exhibition in that city. One night he went to the tower of the Pennsylvania railroad station and watched the light stationed at the Exhibition building on 32d street. The ray of light when turned at right angles to his direction looked like a silver arrow going through the sky; and when turned on him, he could read the fine print of a railroad time table at arm's length. Flashes from his search light were seen at a distance of thirty miles.

In using incandescent lamps for night signaling, the simplest way is to arrange a keyboard with keys marked with certain numbers, indicating the number of lamps arranged in a prominent position, which will burn while that key is being pressed. For example, suppose the number 5348 means "Prepare to receive a torpedo attack." Press keys 5, 3, 4, 8, and the lights of lamps 5, 3, 4, 8, successively blaze out.

Electrical launches have been used to some extent, their storage batteries being first charged ashore or on board the ship to which the launch belongs. They have carried hundreds of people, and have made eight knots an hour. The improvement of storage batteries, steadily going on, will eventually cause the electrical launch to replace the steam launch. One of its advantages is in having no noise from an exhaust and no flame flaring above a smoke pipe to betray its presence. In warfare two sets of storage batteries should be provided for launches, one being recharged while the other is in use.

Mr. Gastine Trouse has recently invented "an electric sight," a filament of fine wire in a glass tube covered with metal on all sides save at the back. The battery is said to be no larger than a man's finger, and to be attached to the barrel near the muzzle by simple rubber bands, so arranged that the act of attaching the battery to the barrel automatically makes connection with the sight; and so arranged also that the liquid of the battery is out of action except when the musket is brought into a horizontal position for firing.

To throw a good light upon the target the same inventor has devised a small electric lamp and projector, which is placed on the barrel near the muzzle by rubber bands, the battery being held at the belt of the marksman, with such connections that the act of pressing the butt of the musket against the shoulder completes the circuit, and causes the bright cylinder of light to fall on the target, thus enabling him to get as good a shot as in the day time.

Search lights and incandescent lights are advantageously used with balloons. In submarine boats electricity will one day be very useful. Submarine diving will play a part in future wars, and the diver's lamp will be electrical.

Progress has been made also in constructing "electrical guns," in which the cartridge contains a fuse which is ignited by pressing an electric button on the gun. A better aim can be had with it, when perfected, than with one fired by a trigger. At present, according to Lieut. Fiske, this invention has not reached the practical stage, and the necessity for a battery to fire a cartridge is decidedly an objection. But the battery is very small, needs little care, and will last a long time. The hard pull of the ordinary trigger causes a movement of the barrel except in the hands of the most highly skilled marksmen, and this hard pull is a necessity, because the hammer or bolt must have considerable mass in order to strike the primer with sufficient force to explode it. Having the mass, it must have considerable inertia; hence it needs a deep notch to hold it firm when jarred at full cock, and this deep notch necessitates a strong pull on the trigger. But with an electric gun the circuit-closing parts are very small and light, and can be put into a recess in the butt of the gun, out of the way of chance blows.

Thus a light pressure of the finger is alone needed to fire it, while from the small inertia of the parts a sudden shock will not cause accidental closing of the circuit and firing of the gun.

[5]From a recent lecture before the Franklin Institute, Philadelphia.