Dictionary of National Biography, 1885-1900/Coventry, John (1735-1812)
COVENTRY, JOHN (1735–1812), constructor of philosophical instruments, was born in Southwark in 1735. He made a position through the care with which his instruments were made. He was the inventor of a new hygrometer, more accurate than any which had been previously in use. This instrument was very generally employed by the chemists and other scientific men of his day. His telescopes were found to be more accurately adjusted than those usually employed, and the lenses with which they were fitted were more truly ground. His graduations were especially correct. He was a friend of Benjamin Franklin, who appears to have consulted him on questions connected with electrical apparatus. Coventry died in 1812.
[General information from private sources.]