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. Mural Quadrant - by John Bird - London 1773.jpg|Mural quadrant constructed as a frame mounted on a wall. This instrument was made by Bird in 1773 and is in the
History of Science Museum, Oxford ==References==