An instrument designed by Mr. BIZET, School Director in Paris and Officer of Public Instruction in 1897.

This device is used to calculate the salary of an employee based on an hourly rate.

This instrument was used probably by traders as a table, but this theory remains to be confirmed.

This arithmographe multiplies figures ranging from 15 to 95 with figures ranging from 100 to 1000.

The objective of this scale is to give rapidly the result of multiplying a quantity by a unit price in order to get the total price.

This instrument used in Holland can do calculations for currencies exchanges.

This chart allows you to work with three input parameters. One of the inputs is the diameter of round iron used in reinforced concrete.