Seidel & Naumann - 1910
"This is a chain drive adding machine, serial number 4665, manufactured in Germany by Seidel & Naumann around 1910.

Numbers are entered by using a stylus to pull each individual rack down to the crosspiece at the bottom. The number can then be verified before it is added, which is done by depressing the lever at the lower right. For rapid data entry, the lever can be set to M, and the chains automatically spring back after the numbers are entered.

Pulling the small crank, which automatically springs back to its neutral position, clears the result mechanism.

The machine features automatic tens-carry as well. Using the scales on the sides, which display complementary digits, one can perform subtraction." 

Jay M. Goldman.

Courtesy of:  Jay M. Goldman

X-Number World of Calculators