This Monroe calculator was used by the curator's grandfather, David Roswell. It rapidly adds, subtracts, multiplies and divides. Like many calculators of its time, it has a grid of numbers for data entry. This both simplified the mechanical design, and allowed for faster data entry. Can someone show a modern device that allows us to enter a multi-digit numbering parallel rather than one digit at a time?
System Source has a large collection of Monroe Calculators from the collection of James Joseph Donohue (donated by his daughter Susan Marks) Joe was not one for waste. When customers upgraded to a new model machine and traded in the old one, it was company policy for the old machine to be destroyed. Joe never got around to destroying these old machines. And so, we are able to appreciate this wonderful historic display of business machines today.