He was also well versed in physics and mathematics, on which he wrote a number of papers and thus was elected a Fellow of the Royal Society in 1767; and secretary in 1773, but, in consequence of a difference with the president (Sir Joseph Banks) he withdrew in 1784.

[1] Horsley now entered his controversy with Joseph Priestley, who denied that the early Christians held the doctrine of the Trinity.

In this fierce debate, Horsley's aim was to lessen the influence which Priestley's name gave to his views, by pointing to (what he claimed were) inaccuracies in his scholarship.

The effective support which he afforded the government was acknowledged by his successive translations to Rochester in 1793, and to St Asaph in 1802.

Sarah had been a servant of his first wife, but her elegant manners impressed Queen Charlotte when she was presented at Court.