Agnes Mary Clerke,
Dictionary of National Biography…
(1890)
“ By the marriage of his daughter, Janet, with John Gregory, the hereditary mathematical genius of the Andersons was transmitted to the Gregorys and their descendants. James Gregory's education, begun at the grammar school of Aberdeen, was completed at Marischal College. His scientific talent was discovered and encouraged by his elder brother David (1627-1720) [q. v.] , and he published at the age of twenty-four ‘Optica Promota’ (London, 1663) , containing the first feasible description of a reflecting telescope, his invention of which dated from 1661. ”
