Print (mezzotint). Engraved by Valentine Green after John Lewis; published by Valentine Green, London, 1776. Titled 'JOHN BIRD of LONDON, | Who furnished the Chief Observatories of the World, with the most Capital Astronomical Instruments divided by him after an improved | method of his own, in a manner superior to any executed before, for which, and many other Improvements in the Construction of | Astronomical Instruments, he was honoured with a considerable Recompence from the Commissioners of Longitude. | Died the 31st. March 1776, in the 67th. year of his age.' The print is a half-length portrait of John Bird, shown seated at a table in front of a curtain backdrop. Lying on the table are a beam compass, Bird's publication 'The Method of Constructing Mural Quadrants', and a diagram of a mural quadrant lettered 'J. Bird Sculp'. The composition is enclosed by a simple, rectangular trompe-l’oeil frame. Lettered underneath the image with title, and maker and publication details as follows: 'Lewis Pinxit.'; 'Engraved by V. Green, Engraver to his Majesty, & to the Elector Palatine.'; 'Published Decr. 2, 1776, by V. Green, Engraver to his Majesty &c. Salisbury Street, Strand.'

John Bird began as a clothier but later turned to scientific instrument-making. He established a reputation for constructing, and accurately dividing the scales of, large quadrants for astronomical observatories.

This mezzotint depicts Bird with examples of his intellectual output and tools of the trade: his own diagram of a mural quadrant; his publication 'The Method of Constructing Mural Quadrants'; and a beam compass that would have been used to draw and divide the scale arcs on such instruments. Such was his skill that the Board of Longitude, the government body concerned with the improvement of navigation, requested he share his techniques with other makers. In return they granted him £500, around ten times the annual salary for a skilled tradesman.

One of Bird’s mural quadrants, made for the Radcliffe Observatory in Oxford, is now in the Science Museum Group’s permanent collection (SMG object number 1935-4). His publication 'The Method of Constructing Mural Quadrants' is also held by the Science Museum Library and Archives (call number Q O.B. BIR BIRD).