HENRION, Denis (or Didier). Usage du compas du proportion. Paris: Michel Daniel, 1618.
First edition, extremely rare, of Henrion’s treatise on the proportional compass, the work that introduced the instrument to France. The proportional compass, also known as the sector, geometric compass, or military compass, was an analogue calculating instrument used widely from the late 16th century until modern times. Its origins are uncertain, but it was first described in print by Thomas Hood in 1598, and developed at about
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