When a screw breaks off in a brass or other soft-metal plate, dig it out in the usual manner, and, whether the thread in the hole is injured or not, a screw a trifle larger can be quite easily fitted, without the use of a tap. in the following manner: Leave just enough of the thread intact to tap the hole. Harden the point of this improvised tap by heating it over a gas jet and dipping it in water. Now work the screw in the hole like a tap, and when the desired fit has been reached cut off the tap end, and you have a good screw left. The writer has fitted several screws in this way, two being in a brass plate over 1/8 inch thick.