The whole apparatus is suspended from a long cable, formed of two conducting wires, which winds around a windlass with metallic journals which are electrically insulated. These journals communicate, through the intermedium of two friction springs, with the conductors on the one hand and, on the other, with the poles of an automatic and portable battery. [Illustration: THE TROUVE ERYGMASCOPE.] This permits of lowering and raising the apparatus at will, without derangement, and without its being necessary to interrupt the light and the observation.--_Revue Industrielle._ * * * * * A NEW ELECTRIC BALLISTIC TARGET. The electrical target usually employed in determining velocities of projectiles consists of a wooden frame on which is strung a copper wire so as to make a continuous circuit arranged in parallel vertical lines about one inch or one and one half inches apart. It frequently happens that a projectile will pass through this target without breaking the circuit, either by squeezing between the wires or because, when last repaired, the target was short-circuited unnoticed, so that the cutting of the wires did not break the circuit. The repair of this target takes considerable time. _______________________________________________________ | { | +-------------__ --------------__---------------- } | | _ // \\ // \\ } { | | |_| || C_{0} || A || || || A { } | | P \\ // \\ // } { | +------------- --------------- ---------------- } | F { |_______________________________________________________} Plan. P C =|= _________ |===| ========= A A ========| | S |========\_______/================= |spring | | | | | | | | |S_ | __| |__ __| ||| | | ___________|||______________| |_____________________ | | Section. H / \+/ | | | | | | _____+_____ | | | W | | | |___________| Besides these objections to this target, another and more serious one is the irregularity in the manner of breaking the circuit. It has been proved that times required for a flat headed and an ogival headed projectile to rupture the current are very different.