An Account of a Method of dividing Astronomical and other Instruments, by ocular Inspection in which the usual Tools dor graduating are not employed" the whole Operation being so contrived, that no Error can occur but what is chargeable to Vision, wh.

(London, W. Bulmer and Co., 1809). 4to. No wrappers as extracted from "Philosophical Transactions" 1809 - Part I. Pp. 105-145 and 3 fine engraved plates, showing instruments. First appearance of the importent description of the division of the circle, invented by Troughton.One of Troughton's most important contributions was a method of dividing a circle. His paper on this, An account of the method of dividing astronomical and other instruments by ocular inspection in the Philosophical Transactions of the Royal Society in 1809 won him the Copley medal of the Royal Society. In this invention is described in detail and also put into context. "Troughton made many contributions to the development of instrument making: in 1788 an improvement of Hadley's quadrant" in 1790 a mercurial pendulum" and in 1796 a refined version of the Borda, or reflecting circle. He was responsible for substituting spider web filaments for hair or wire in his optical instruments.Troughton's most notable achievement was the improvement of the method of dividing a circle. His paper on this in 1809 won him the Copley Medal from the Royal Society, which elected him as fellow the following year."(DSB). - Poggendorff II: 1140.…