Steam engine polar planimeter "for measuring the areas of diagrams produced by steam engine indicators, devices attached to steam engines to measure their horsepower and identify potential problems inside the engine."

Fullsize image: https://diqn32j8nouaz.cloudfront.net...g_fullsize.jpg


Fullsize image: https://diqn32j8nouaz.cloudfront.net...1_fullsize.jpg


Fullsize image: https://diqn32j8nouaz.cloudfront.net...2_fullsize.jpg


Fullsize image: https://diqn32j8nouaz.cloudfront.net...3_fullsize.jpg



More info on the instrument:

https://www.maa.org/book/export/html/478808


Previously:

Planimeter - photo
Perspective drawing technique using string - GIF
Section liner drawing instrument - GIF
Constrained ball line drawing aid - photo