Archive of Collections

Details and Image

TypeModel No.MakerCountryConstruction
DateScale LengthArea of Use
Willis Improved Planimeter
James L. Robertson & Sons
Chrome plated brass
ca. 1905
Determining Mean Effective Pressure from indicator diagrams

Notes: "This is the improved model of the Willis Planimeter, incorporating the changes in the 1896 and 1901 patents. The tracing wheel on this one rides on ball bearings along a triangular blued steel rod. "

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