An example of the "Evans Friction Cone" variable-speed drive. This simple yet effective of providing an infinitely variable-speed drive - using two opposing cones with some sort of friction material trapped between and sliding along them to transfer the drive - was not new. It appears to have been similar to one granted a patent by Otis Pettee on March 25th 1825 and described as "Pettee, Otis; changing the motion of machinery, Newton MA". Otis Pettee (1817-1853) lived in Newton Upper Falls, and founded the Pettee Machine Works, a company that manufactured cotton machinery. Unfortunately, patents taken out before 1836 are unavailable; they were destroyed in a fire that year, and so precise details of Pettee's invention are not known.
A much larger unit of this kind, capable of handling up to 50 h.p., had been devised by Mr. George P. Evans, of Newton Centre, and manufactured by his company, The Evans Variable Speed Cone Co. and called, naturally enough, the Evans Friction Cone. The system was not just used on large machine tools but even one watchmakers' lathe, the American Cowels - the Archive page entry for this lathe giving further details and pictures of the mechanism.