Thornhill, West Yorkshire
In 1767, John Michell became Rector of Thornhill, now a suburb of Dewsbury, between Huddersfield and Wakefield. Sometime in the early 1770s, he played music with William Herschel and gave Herschel his first telescope. In 1784, he wrote on astronomy, deducing the existence of black holes from Newton's corpuscular theory of light and suggesting that some stars might have dark companions and how to detect these. He also devised and built the torsion balance for determining the universal gravitational constant G. He died before having time to use it and it was passed to F. J. H. Wollaston, Jacksonian Professor at Cambridge and brother of W. H. Wollaston. Wollaston did not have time to use it and passed it on to Henry Cavendish, who used it at his house in Clapham, South London. Lord Brougham's account attributed the balance to Cavendish - an error which persists to this day. Michell died at Thornhill and is buried in the south chancel of St Michael's church there, with a commemorative plaque nearby.
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Michell attracted Benjamin Franklin, Joseph Priestley, John Smeaton and others to a scientific meeting and overnight stay in 1771. Benjamin Franklin's stay in Thornhill remained unknown until 2015.
To see an Ordnance Survey map click at
An extract from
The Mathematical Gazetteer of the British Isles
created by David Singmaster
The original site is at