Some equipment required finer or even variable control over drive speeds. In keeping with the brilliance of Victorian-age engineering on both sides of the Atlantic, one solution was the "Evans Friction Cone". This mechanism was invented by Mr. George P. Evans of Newton Centre, MA. The two tapered cones with a movable belt between them could quickly and without stopping vary the speed of any machine to which it was connected. The product was shipped to all parts of the world. It was first manufactured in the old Crane Company shop in Newton Highlands, MA, but in about 1900 a new factory was built on Needham Street. After 41 years of operation the expiration of patents and the use of variable speed motors reduced the need for the product, and the factory was forced to close. (This description has been adapted from an article by the late Kenneth W. Newcomb on the website of the Friends of Hemlock Gorge - [dead link])

I think Dutch manufacturer DAF used a similar mechanism in one of their cars in the 70's -- a car with just one forward and one reverse gear.