The Comptometer Super Totalizer, a mechanical calculator.

This is a mechanical calculator, the Comptometer by Felt & Tarrant. This is a special version of the Model J, called the Super Totalizer.
I explain how it works, and what all the buttons and levers do.

This one has serial numbers J317903 and S1415. From the range of serial numbers found, it seems that some 85900 model J Comptometers were made, of which maybe 2000 were Super Totalizers.

This one has had a little restoration work done. Nine of the keys have had new tops fitted at some point. The windows over the digits seems to have been changed from celluloid film to more modern transparent plastic. Other than that it seems all original.

Some minor corrections and additions:
I say in the video that it was made in 1931, but it is more likely to be 1934 or 1935, as the patents were filed in November 1934.

The black paint on the case decoration is probably original. It looks like models H and J had this painted black, but earlier versions like the model F did not.

The blinds on the digits of the front register do a bit more than just cover up a digit. It also blocks any carries from that digit, so any hidden wheels cannot affect the visible ones.

You can find more information on my site:
http://www.jaapsch.net/mechcalc/

For a more detailed explanation of performing arithmetic on the Comptometer, see my other video:
   • Comptometer Arithmetic