enter image description here How does this instrument work? Here is a video that demonstrates its use.

After reading the wikipedia page, I still have no idea how it works. Any explanations that are easier to comprehend?

  • $\begingroup$ This link may be useful. It also links to a Java planimeter with an example usage. $\endgroup$ Jun 16, 2011 at 0:32
  • $\begingroup$ Originally posted to skeptics.SE. $\endgroup$ Jun 16, 2011 at 0:42

1 Answer 1


See Robert L. Foote: Geometry of the Prytz Planimeter. See also Mark Levi and Serge Tabachnikov On bicycle tire tracks geometry, hatchet planimeter, Menzin’s conjecture and oscillation of unicycle tracks, and Tom Apostol and M. Mnatsakanian: The method of sweeping tangents.

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    $\begingroup$ I must be missing something, I still do not get it. $\endgroup$
    – picakhu
    Jun 16, 2011 at 2:50
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    $\begingroup$ I'm sure you know this, but unless it is outside of the scope of the site, we usually prefer full answers to be posted here, rather than links to answers; the point being that if those sites went down, the answers here would still be valid and helpful to future googlers. $\endgroup$ Jun 16, 2011 at 7:38
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    $\begingroup$ @Blue Plenty of answers here consist of links - esp for answers whose length would be inordinate without links. It does not make sense to attempt to completely duplicate the entire mathematical corpus here. And who is "we"? $\endgroup$ Jun 16, 2011 at 12:51
  • $\begingroup$ @Blue: I completely agree with Bill here. All the articles linked to should be trivial to find with the given information, even if the links should happen to break. I really think that it is exaggerated to ask for a summary of non-trivial articles written by renowned and outstanding mathematicians who evidently put a lot of effort into making their work understandable to as wide an audience as reasonably possible. By the way: ArXiV-links are guaranteed to be persistent. $\endgroup$
    – t.b.
    Jun 16, 2011 at 13:54
  • $\begingroup$ @pic What precisely don't you get? Did you read the nice exposition in section 2 of Foote's paper. If something about this is not clear then I'm sure folks here would be glad to assist you if you ask specific questions about such in your question. $\endgroup$ Jun 16, 2011 at 15:35

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