In a refracting telescope we have to employ what is known as the achromatic combination, consisting of one lens of flint glass and one of crown glass, adjusted to suit each other with extreme care.
"The Story of the Heavens"
Robert Stawell Ball
Mr Bayly observed with the achromatic telescope belonging to the board of longitude; Mr King, with the reflector belonging also to the board; and I made use of my own reflector of eighteen inches.
"A General History and Collection of Voyages and Travels, Volume 16"
Robert Kerr
I attempted to trace it with a small achromatic, but found its magnifying power not sufficient.
"A General History and Collection of Voyages and Travels, Volume 16"
Robert Kerr