Davies Adding Machine
From the collection of National Museum of American History. Free to download, adapt and use — no permission needed.
This U.S. Patent Office model has five continuous metal bands that move in slots across a wooden frame. Flat pieces of brass cover the top of the frame on the right and the left, keeping the bands in their slots. The bands are made up of small flat squares of metal, with nine squares silver-colored and the tenth one brass. Each square has a hole at the center for a stylus. Strips of paper attached between the bands have the numbers from 1 to 9. Moving a band to the right turns a wheel clockwise. The edge of this wheel, which is covered around the edge with a paper marked with the digits from 0 to 9, is visible through a window in the right piece of brass. The number shown increases as the wheel turns. A lever on the left side disengages the fourth and fifth columns. According to the patent description, there is a carry mechanism activated when a wheel passes 9.
National Museum of American History’s own description
