John Bird

John Bird (1709– 31 March 1776) was a British mathematical instrument maker with an interest in astronomy who was notable for making high quality mural quadrants, octants, and sextants. Nevil Maskelyne used sextants made by Bird that had telescopes specially made by John Dollond and his son Peter.

Life and work

Bird was born in Bishop Auckland, County Durham and initially worked as a weaver. He became interested in the marking of divisions on clock dials and began to experiment on it and developed the skills. He became a friend of the mathematician William Emerson and he was able to recommend Jeremiah Dixon as a choice for the Woolwich Academy to send to St. Helena to study the transit of Venus. He came to London in 1740 where he worked for Jonathan Sisson (and his son Jeremiah) and later George Graham. By 1745, he had his own business was at the sign of Sea Quadrant, Court Garden, in the Strand. Bird was commissioned to make a brass quadrant 8 feet across for the Royal Observatory at Greenwich, where it was mounted on 16 February 1750, and where it is still preserved. Soon after, duplicates were ordered for France, Spain and Russia. The quadrant was considered to be of great quality as three years later it was off by just 0.5 minutes of the degree despite the temperature effects on metals. In 1764 Bliss and Bird made measurements of the diameter of the moon using a 2-foot reflecting telescope. Thomas Hornsby hired Bird to make instruments for the Radcliffe Observatory, Oxford, and his Equatorial Sector is one of the few that still exists. Along with Captain John Campbell, he designed portable sextants for use at sea.

Bird supplied the astronomer James Bradley with further instruments of such quality that the commissioners of longitude paid him £500 (a huge sum) on condition that he take on an apprentice for 7 years and produce in writing upon oath, a full account of his working methods. This was the origin of Bird's two treatises The Method of Dividing Mathematical Instruments (1767) and The Method of Constructing Mural Quadrants (1768). Both had a foreword from the astronomer-royal Nevil Maskelyne.

Bird, with his fellow County Durham savant William Emerson, makes an appearance in Mason & Dixon, the acclaimed novel by Thomas Pynchon.