BALLISTIC PENDULIIM.—The use of this apparatus as a test of the initial velocity of projectiles has nearly ceased, its place having been taken by the electro-ballistic apparatus of maj. Navez, a distinguished Belgian officer. This apparatus consists of a pendulum moving on a graduated arc of a circle, at a known velocity, at the top of which it is held by an electromagnet. The projectile is fired through two screens at a known distance apart. Ili passing through the first screen it breaks the electric circle and nemagnetizes the magnet, causing the pendulum to fall. As the ball passes the next screen it restores the circuit and the magnetic power, instantly arresting the pendu lum in its downward course. The portion of the circle passed over by the pendulum shows the time occupied by the ball in passing from screen to screen; and that being known, the initial velocity becomes a question of very simple calculation. Of course the magnet and the two screens are connected by wires with a voltaic battery.
BARRACKS.—The office of barrack-master-general had been abolished in 1822, ands the duties transferred to the board of ordnance. On the extinction of that board 1855, barracks came under the control of the secretary of state for war, who confided. the executive to two departments of his office—the director of works in regard to build ings and lands, and the superintendent of the barrack department in regard to the per sonnel. The system of government was so far altered that all the barrack-masters im any military district were supervised by one of their number, who ranked as district barrack-master. The correspondence of the whole district with the war office was conducted through this officer. Barrack-masters were granted relative rank and increased pay, with some other minor advantages.—For the most recent changes,