Page 406 - 89 history of astronomy_opt

Newton’s trouble with refractors, chro-
matic aberration, remained insurmountable
until John Dollond (born 1706, died 1761),
after many experiments, found out how to
make an achromatic lens out of two lenses–
one of crown glass, the other of flint glass–
to destroy the colour, in a way originally
suggested by Euler. He soon acquired a
great reputation for his telescopes of mod-
406