Dollond

Dollond, John (1706-1761), a famous English optician. His father, who was a silk-worker in Normandy, came to England as a refugee, and worked at Spitalfields, where the son worked at Dptics and science in his little shop. Dollond's shief claim to fame was his invention of the achromatic lens, in spite of Newton's belief that it was impossible to avoid the decomposition to rays Owing to refraction. He brought about this improvement by employing a double concave of crown glass and a double convex of flint glass, thus making One lens counteract the refraction of the other. By this means telescopes could be made less bulky and more accurate. Dollond's invention gained for him the Copley medal and the membership of the Royal Society. His son Peter and his nephew George and other members of the family carried on his'improvements in optical instruments.