The lock shown in the sketch and detailed drawings is made entirely of wood, and it is nearly impossible to pick or open it without the use of the key.
Three tumblers, a bolt, and a keeper are required. The key is shown inserted, indicating how the tumblers are raised by it.
The bolt is slotted and a screw placed through it to prevent it from being moved too far.
The lock and keeper are bolted into place on a door with carriage bolts, the heads being placed on the outer side.
The detailed drawing shows the parts, together with the dimensions of each, which must be followed closely.
The lock casing is grooved with two grooves, extending the length of the grain and connected by open mortises all 1/2 in. in depth.
The spacing of the mortises and the grooves is shown in the views of the casing.
Three tumblers, 1/2 in. square and 2 1/2 in. long, are required.
The bolt is 1/2 by 1 by 8 in., and the key 1/4 by 3/4 by 5 1/2 in., and notched as shown.
All the parts of the lock must be fitted carefully, sandpapered smooth, and oiled to give a finish that will aid in the operation, as well as protect the wood.
Aside from its practical use, this lock is interesting as a piece of mechanical construction.
—B. Francis Dashiell, Baltimore, Md. THE BOY MECHANIC – BOOK 3 – 800 THINGS FOR BOYS TO DO 1919, POPULAR MECHANICS PRESS CHICAGO