Keuffel & Esser model 1740 Thacher slide rule
physical object
2013.5.10
Description
This cylindrical slide rule made by Keuffel & Esser Co. is believed to have been owned and used by W.H. Breithaupt, an entrepreneur and engineer who was influential in the development of the Waterloo region during the early 20th century.
Edwin Thacher patented this design in 1881. It permits a slide rule small enough to fit on a desk, but equivalent to a normal, linear slide rule over 17 metres long, by writing the logarithmic
scale in a spiral around a cylinder.
Keuffel & Esser of New York began selling Thacher-style slide rules in 1883, and making their own under license around 1887.