Democratic Sentinel, Volume 19, Number 13, Rensselaer, Jasper County, 5 April 1895 — SPEED OF CANNON BALLS. [ARTICLE+ILLUSTRATION]

SPEED OF CANNON BALLS.

How Artillery Experts Measure It with Exactness. The measurement of the speed of bodies in rapid movement is effected by special mechanical contrivances in connection with electric coutaCtsand self* registering clock-work. The Following is tije procedure adopted: TheVbroJ nometer or other time-piece to be usecfL, for the purpose is electrically connect-! ed with two circuit-breakers, one each end of the proving ground. The discharged projectile in its flight strikes I both in turn, starting the chronoscope; at the first contact and stopping it at ; the second, thus registering the interI val of time between the two. In prac-j | tical experiments, the line of flight of the projectile is intercepted by two disklike frames (C and D in the illustration)! at a measured distance apart, and sup-? ported by the posts A and B, sunk in the earth. The distance between the two frames is ordinarily 50 meters—ss, or 56 yards—and the two are so placed that the projectile will pass through them about the middle. Both framed are made of parallel wooden slats, and are provided on their perpendicular sides with small pegs supporting a thin copper wire that passes alternately I from one side to the other, without in» terruption. In this way the frame bel comes a net-work, in which the diame-j ter of each mesh is smaller than that of the projectile to be fired through It' The wire of the first frame C Is In thei circuit of the current of a galvanic battery, S, and both are attached to the) chrometer T by means of the clamps

and 2. The connection of the several parts Is shown in the normal condition, the circuit being closed, the needle or hand of the chronoscope points to 0. But the instant the shot passes the wire meshes of the frame C the circuit Is broken and thei needle deviates. The frame Dls simi-j larily connected with the battery S, ! which In turn, by means of the clamps 3 and 4, Is connected with the meter. The result is that the hand of the timepiece Is again arrested the in-’ stant the ball cuts the wire in this sec-1 ond frame. The measure of deviation! from the zero-point during the interval! Indicates the time occupied by the projectile in passing from one frame to the other, and enables us to calculate the rate of speed.

MEASURING ITS SPEED.