Per C. Gordon Bell's artifacts website: Keuffel & Esser 4242 planimeter, SN# 2066. Black box with silver and black tracer and pole arms on royal blue velvet backing. Purchased in July 2005 from Betty Ann and Fred Centanni. As a junior at MIT in 1965, Mr. Centanni was given the planimeter by one of his professors for helping to clean out a laboratory.