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.