Page 403 - 89 history of astronomy_opt

suggested the convex eye-lens in 1611, and
Scheiner claimed to have used one in 1617.
But it was Huyghens who really introduced
them. In the seventeenth century telescopes
were made of great length, going up to 300
feet. Huyghens also invented the compound
eye-piece that bears his name, made of two
convex lenses to diminish spherical aberra-
tion.
403