The transmission accelerated each rotation of a brace at a ratio of 1 to 5 allowing more rapid rotation of a bit in the transmission chuck.

I have assembled a research collection of patented bitstocks and bitstock tools over the past 50 years and in the early years found some rare ones before they were known to be rare.

I have seen lots of bitstock tools over the years and have been tied into the collector market since circa 1970, where I was able to find lots of bitstock tools. I have come to the conclusion that just about every tool in the patent records was actually manufactured, albeit in a very limited quantity.

The tool in the first photo is a geared transmission that was used in drilling, much like an eggbeater drill. The transmission accelerated each rotation of a brace at a ratio of 1 to 5 allowing more rapid rotation of a bit in the transmission chuck.

This tool required an assistant to hold the geared transmission
tool while another cranked the brace.

This device was patented on March 18, 1873 by G. Gibbs. It is marked, MILLERS FALLS" on the chuck. In all my years of searching, this is the only specimen of this tool I have ever seen.

It is marked with the patent date.

The Chuck is marked, MILLERS FALLS.