Dollond, JOHN

Dollond, JOHN, a distinguished optician, inventor of the achromatic telescope, was descended from a French refugee family of Dutch extraction, and was born in London, June 10, 1706. Brought up to his father's occupation of silk-weaving, and engaged at the loom all day, he devoted great part of the night to his favourite studies of mathematics, optics, and astronomy; and even made himself acquainted with anatomy, theology, Greek, Latin, French, German, and Italian. In 1752 he joined his eldest son, Peter (1730-1820), who had started as an optician, and devoted himself to the improvement of the dioptric telescope, in which he was encouraged by the most distinguished scientific men of the time. After a series of well-contrived experiments and researches, carried on for several years, he succeeded in constructing lenses that produced images without any coloured fringe (see ACHROMATISM). This was undoubtedly the greatest improvement that the telescope had received since its first invention, though it came out in action for infringement of patent, that in 1733 it had been anticipated by Chester More Hall, who had not, however, made his invention public. The Memoir (published in the Philosophical Transactions for 1758) in which he gave an account of his investigations was rewarded by the council of the Royal Society with the Copley Medal. In 1761 Dollond was elected an F.R.S.; he died 30th November of the same year. His two sons continued to carry on the business with great reputation and success. See Kelly's privately printed Life, reproduced in the Philosophical Magazine (1804).