Cooper Hewitt says...
From British Museum: "Painter, antiquarian, draughtsman, dealer, engraver; began his career as a painter, but then became an antiquarian-dealer, principally through his activities as Librarian to George, Prince of Wales (subsequently George III). He first travelled to Italy in 1739 to continue his studies, first at Bologna, then at Rome, where he specialised in highly finished red chalk drawings after classical statues. By mid-1741 Dalton had also become active as a dealer, particularly in prints. He returned to London in 1743, but left again for Rome in 1747. In Sicily in 1749 he encountered Lord Charlemont and his party and joined them as travelling draughtsman on their tour of Constantinople, the Levant, and Greece. The drawings Dalton then made are important as the first visual records of a number of ancient monuments; many were subsequently published in Dalton's 'Musaeum Graecum et Aegyptiacum' (Antiquities of Greece and Egypt, 1751 with additional later issues) and 'Antiquities and Views in Greece and Egypt' (1791). In 1754 he offered casts after the antique as well as prints after Raphael et al. at his London lodgings; in 1755 he was appointed Librarian to George, Prince of Wales. In order to enrich the royal collection Dalton travelled to Italy again in 1758-9, where, among other things, he examined Cardinal Albani's collection of drawings (later acquired for the King through James Adam). Dalton became Antiquary at the Royal Academy in 1770. He went to Italy again in 1768-9 and 1774-5, buying paintings and drawings both for the Royal collection and his own, as well as a number of British noblemen. In 1778 he was appointed Surveyor of the King's Pictures. His collection, which included some antiquities, was sold at Christie's in 1791."
