Used with permission of Maiken Naylor, University at Buffalo, Buffalo, NY, USA, http://ublib.buffalo.edu/libraries/units/sel/exhibits/stamps

In the centuries succeeding Galileo, optical instruments proliferated and increased in precision, making possible scientific discoveries beyond the capabilities of the naked eye, from the galactic to the microscopic. Shown above are specimens from the late 18th and 19th centuries: a Borda reflecting circle, reflecting telescope, binocular microscope, and octant.

Jean Charles de Borda (1733-1799), a French mathematician and nautical astronomer, devised many instruments, among them a reflecting circle. Together with Delambre and Mechain, Borda used this to measure the length of an arc of a meridian between Dunkirk and Barcelona in 1790 . Borda, whose most significant work was done in hydraulics, strongly supported the introduction of the metric system and originated the word "metre" for its basic unit of length.