Scope and content Calculating devices from the late 19th and early 20th centuries, including two circular slide rules, three other slide rules, a set of Fischinger drawing instruments (mainly compasses), and several manual adding machines of various designs, including a Thales calculator. One of the flat (non-circular) slide rules is made by Tavernier-Gravet, maker of mathematical instruments in Paris. Most of the adding machines involve a stylus and a metal panel where the calculating is done; the Thales...