DOL'LOND, dons (170(i•gl A di-difigntishod English optician. inventor of the achromatie object-glass for telescopes, lle was the son of a in Ill11111/11' eircuutslanecs who bad route to London as a French refugee. Dollond followed his father's occupation. but 1V114 also able to devote himself to the study of mathe matics, optics, and astronomy. In addition he muds aerlvainted with anatomy and theology, and wont so far ill the study of the languages as to translalt• the llreek Te.stitnient into Latin. and was also able to read French, (:critian, null Italian. Ile apprenticed his eldest son, Peter, to an optician; and after the latter had established himself in business on his own account, he was joined by his father in 1752. John Dollond now devoted himself to the improvement of the refracting telescope, in which work he was encouraged by the most distinguished scientific men of the tune. After
a series of well-contrived experiments and re searches, commenced in 1757 and carried on for several years, he succeeded in constructing lenses where a concave lens of flint glass was combined with a convex lens of crown glass with the re sult that images were produced without any colored border. (See AennomArism.) This was undoubtedly the greatest improvement that the telescope had received since its first invention. The memoir (published in the Philosophical Transactions for 17581 in which he gave an ac count of his investigations, was rewarded by the council of the Royal Society with the Copley medal. In 1761 Dollond was appointed optician to the King. and was elected a fellow of the Royal Society. His two sons continued to carry on the business with great success. Consult Kelly, Life of John Dollond (1.ondon• 1808).