This ‘Addiator’ Calculating Machine was made for adding and subtracting Pound, Shilling and Pence. This is a flat stylus slide adder made of brass, very simple in construction and comes in a special leather covered wallet. Also in the wallet is a note pad, instructions for use and examples of various calculations. The machine consists of two mechanisms, one side for adding marked +, and the other for subtracting marked -. Following calculations, it is cleared by pulling a small bar on the top.