Maker's Name: 
15.9 × 4 × 0.4 cm

Mechanical Calculator for doing addition and subtraction. Vertical scales are moved with a stylus, the top half set of scales are for addition, and the bottom half of scales are for subtraction. The result is shown in column totals between the 2 sets of scales. This calculator was designed for calculations in Pounds, shillings and pence. Note how the pence (d) carry to shillings (s) at twelve and the shillings carry to pounds (£) at twenty.