Map planimeter for measuring actual distances and areas on maps.
Fullsize image: https://diqn32j8nouaz.cloudfront.net...l_fullsize.jpg
Previously:
Early personal and in-car navigation - photos
ancient Chinese south-pointing chariot
Map planimeter for measuring actual distances and areas on maps.
Fullsize image: https://diqn32j8nouaz.cloudfront.net...l_fullsize.jpg
Previously:
Early personal and in-car navigation - photos
ancient Chinese south-pointing chariot
Last edited by Jon; Jan 18, 2020 at 08:35 PM.
New plans added on 11/20: Click here for 2,589 plans for homemade tools.
baja (Jan 21, 2020), greyhoundollie (Jan 20, 2020), Toolmaker51 (Jan 19, 2020)
baja (Jan 21, 2020), greyhoundollie (Jan 20, 2020)
The device is called an opisometer.
https://en.wikipedia.org/wiki/Opisometer
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Regards, Marv
Failure is just success in progress
That looks about right - Mediocrates
Green's theorem notwithstanding, it's not clear to me how one measures area with an opisometer, which measures linear dimensions. Typically area measurements are made with a device called a planimeter. Here's a good description of the device, including some pictures, history, use and its relation to Green's theorem
AMS :: Feature Column from the AMS
Of course, if you're out camping in the forest and have an urgent need to calculate an area, you can always use your pocket knife as a planimeter...
https://www.spaco.org/Blacksmithing/...Planimeter.htm
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Regards, Marv
Failure is just success in progress
That looks about right - Mediocrates
Altair (Jan 23, 2020)
Whoa , that's funny, the Map shown above, this is the place where I grew up, well, 20km above the town up right on the map.
This is what we call here a "curvimètre", not that uncommon, this is still sold and you can event get the digital high tech version :
https://www.amazon.fr/curvimetre/s?k=curvimetre
Cheers !
Christophe
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