Silver Protractor By Sisson, Circa 1735

A small and early rectangular protractor in solid silver bearing the interesting signature of "J. Sisson London", datable to around 1730-1740. The small protractor measures 10.8cmx3.3cm. Jonathan Sisson (1690-1747) was an important English maker of scientific instruments, inventor of the telescope and particular theodolite renowned for its highly accurate divisions. On the signature side is engraved a double scale from 0 to 180 degrees, and on the other side are engraved a scale of divisions and six lines from 20 to 45. Good condition despite some minor damage to the edges. English silver instruments of this period are rare. For another example of almost similar size but of later production by Nairne, see Catalogue of the Andrew Alpern Collection number 11, pages 22-23. The last photo shows the difference in size between a standard-sized rectangular protractor and this example by Sisson.