Graphics

$150

A device used to calculate interest. It is a volvelle with one column titled “Principal” and a cutout for a column titled “Interest.” The page the volvelle is attached is a table of interest by days. As the volvelle is turned to the different days, the cutout column shows the interest gained on the principal amount by that day. While business supplies like this calculator may seem mundane, they document advancement in computation and the tools created to help make jobs easier.