“ His reputation grew rapidly, and in 1761 he was appointed optician to the king. In 1758 he published an “Account of some experiments concerning the different refrangibility of light” (Phil. Trans., 1758) , describing the experiments that led him to the achievement with which his name is specially associated, the discovery of a means of constructing achromatic lenses by the combination of crown and flint glasses. Leonhard Euler in 1747 had suggested that achromatism might be obtained by the combination of glass and water lenses. ”