The Burroughs Calculator with levers and gears just about calculates

Not just any ordinary calculator, this inimitable find is a comptometer from yesteryear. Instantaneous in its display, the Burroughs Calculator as it‘s called has a set of number drums driven by the planetary gears stationed within. The drums are connected to the keys through levers and clutches, which are repositioned to zero using cams. Hailing from the 1920’s, the Burroughs Calculator just like any calculator does mathematical calculations to perfection with the dual numerical keys. The larger numbers assist in addition and multiplication, while the smaller numbers, using the “nines complement” method, help in subtraction and division.

Via: ConsciousFlesh