Hand Drill: Double-Acting Push Drill, Spiral Rod and Ratchet Bevel Gears (Olson, US 652,137, 1900)

Make two half-egg-shaped shells, each with a half-round neck at both ends. Put them face to face and hold them together with ferrules pushed over the necks: a hollow bulb that fits the hand. Not given: the metal, sizes.

Cut a rod with a steep spiral groove or thread. Fit a tube over it with a nut at its lower end that runs in the spiral, and a handle at its upper end. Not given: the pitch, the handle material.

Take four bevel wheels: an upper one bored through the centre and fixed on the lower end of the spiral rod, a lower one the same shape and size, and two side wheels that gear them together. Cut a ring of ratchet teeth on the facing sides of the upper and lower wheels, slanted opposite ways. Make a shaft with a hub (barrel) at its top whose tip runs in the bore of the upper wheel; cut two upright dovetail grooves in the hub, each holding a sliding bolt with its two ends bevelled opposite ways, long enough that one end meets one wheel's teeth while the other end is clear of the other wheel. Ours: steel mitre gears.

Inside the casing, set the upper wheel with the spiral rod coming out of the top neck, the hub between the wheels, and the lower wheel turning loose on the shaft. Run the two side wheels on screws through the casing wall as their axles. Bring the shaft out of the lower neck and fix a drill chuck on its end. Ours: a drill chuck.

Put a bit in the chuck and set it on the mark. Hold the casing still in one hand, pressing lightly toward the work, and push and pull the handle with the other. Each stroke turns the upper and lower wheels opposite ways; the bolts slide over to engage whichever wheel is turning the cutting way, so the bit turns steadily one way.