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
https://diqn32j8nouaz.cloudfront.net...nt_drawing.jpg
Fullsize image: https://diqn32j8nouaz.cloudfront.net...1_fullsize.jpg
https://diqn32j8nouaz.cloudfront.net...t_drawing1.jpg
Fullsize image: https://diqn32j8nouaz.cloudfront.net...2_fullsize.jpg
https://diqn32j8nouaz.cloudfront.net...t_drawing2.jpg
Fullsize image: https://diqn32j8nouaz.cloudfront.net...3_fullsize.jpg
https://diqn32j8nouaz.cloudfront.net...t_drawing3.jpg
More info on the instrument:
https://www.maa.org/book/export/html/478808
Previously:
https://www.homemadetools.net/forum/...923#post175641
https://www.homemadetools.net/forum/...773#post159796
https://www.homemadetools.net/forum/...636#post159259
https://www.homemadetools.net/forum/...805#post156136
