In spite of the constant manual work he had to do, he took advantage of the kindness of an exciseman living in a neighbouring village, who offered to give him some lessons.
A gentleman of Bath, named Kingston, heard of the boy's taste for mathematics, and gave him some help.
Nevil Maskelyne, the astronomer-royal, happened to hear of his talents, and engaged him as an assistant at the Royal Observatory.
In 1772 he accompanied William Wales as an astronomer on Cook's second voyage of discovery to the southern hemisphere.
He also sailed in Cook's third and last voyage made with the Resolution and the Discovery, which departed the English Channel on 14 July 1776.