The Binary slide rule, a circular slide rule
Large circular slide rule with scales on both sides. Despite the term "binary" in the object name, there are no binary scales.
||The Binary Slide Rule
||"COPYRIGHTED 1940" one one side and "COPYRIGHTED 1931" on the other.
overall: 1/2 in x 8 1/4 in x 8 7/8 in
Gift of Jacqueline Tyrwhitt