fig. 1.
fig. 2.
fig. 3.
fig. 4.
The construction of this remarkable Egyptian or pin-lock will be understood from the accompanying engravings. The quadrangular portion, a a [fig. 1], is the case of the lock, screwed or otherwise fastened to the door, having a wooden bolt, b b, passing horizontally through a cavity in it. In the part of the case above the bolt are several small cells containing headed pins, arranged in any desired form; and in the top of the bolt itself are an equal number of holes similarly arranged. The effect of this arrangement is such that, when brought into the right positions, the lower ends of the headed pins drop into the corresponding holes in the bolt, thereby fastening the bolt in the lock-case. A large hollow, or cavity, is made at the exposed end of the bolt, the cavity extending as far as and beyond the holes occupied by the pins. The key consists of a piece of wood (shewn in two positions, [figs. 3] and [4],) having pins arranged like those in the lock, and projecting upwards just to a sufficient distance to reach the upper surface of the bolt. This being the arrangement, whenever the key is introduced and pressed upwards, its pins exactly fill the holes in the bolt, and by so doing dislodge those which had fallen from the upper part of the case. The bolt may, under these circumstances, be withdrawn (as shewn in [fig. 2]), leaving the headed pins elevated in their cells, instead of occupying the position shewn by the dotted lines in [fig. 1]. The cavity in the bolt must of course be high enough to receive the thickness of the key, and also the length of the pins protruding from the key.
This primitive lock comprises many of the best features of the tumbler or lever-locks of later days, as will be seen in a future chapter. There will also be opportunities of shewing how the pin-action has been applied in other ways in some of the modern locks.