Posted 1 year ago
This is a Keuffel & Esser Co. Topographic site level used by surveyors. The product number is 5713PD, the PD meaning the clinometer radient scale could be turned around to read either percentage or degrees. Unfortunately the bubble vial has lost its alcohol. This particular level is one of the items displayed in the Smithsonian Natural Museum of American History in its Mathematical Instruments section. It was manufactured in the USA from 1950-1960.