To make a ball catch, procure a piece of brass, 1 in. long, 1/2 in.wide, and about 1/16in. thick, and an old gas burner having a diameter o f 3/8 in. A s de-scribed by Work, London, the threaded part of the burner is cut off, which forms a contracted end that will hold a steel ball 5/16 in. in diameter and allow it to project 1/8 in. A hole is drilled in the center of the brass plate, and the barrel soldered in place. A piece of spiral spring is inserted behind the ball. The stiffness of the spring will depend on the use of the catch. The barrel is cut to length and plugged. Another plate of brass is fitted with screw holes and a hole in the center to receive the projecting ball part, for the strike.