Page:A Dissertation on the Construction of Locks (1785).pdf/52

 two grooves are cut at oppoſite points, which open a communication with the center at one point; and with the ſpherical ſurface of the block, or barrel, at the other.—The ſmall circle, which marks the center of the flat ſurface A, is the key-hole, which likewiſe forms a paſſage through the barrel, in a parallel line with the cells, which ſurround it.—This figure repreſents the frame, in which, the parts that compoſe the active principle of the Lock, are depoſited.—To render the operation of theſe parts, and their reſpective offices perfectly intelligible, they are both individually, and collectively, repreſented on the plate.

The ſecond figure deſcribes a ſpiral ſpring, which is lodged in the bottom of each cell, and occupies one half of its ſpace. The other half is filled with a ſlider, which reſts on the ſpring, and is repreſented by the third figure. The office of theſe ſliders, exactly correſponds with that of the levers, in