The first telescopes were made in Holland, the originator being either
Henry Lipperhey,[1] Zacharias Jansen, or James Metius, and the date
1608 or earlier.

In 1609 Galileo, being in Venice, heard of the invention, went home
and worked out the theory, and made a similar telescope. These
telescopes were all made with a convex object-glass and a concave
eye-lens, and this type is spoken of as the Galilean telescope. Its
defects are that it has no real focus where cross-wires can be placed,
and that the field of view is very small. Kepler 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 aberration.

But the defects of colour remained, although their cause was unknown
until Newton carried out his experiments on dispersion and the solar
spectrum. To overcome the spherical aberration James Gregory,[2] of
Aberdeen and Edinburgh, in 1663, in his _Optica Promota_,
proposed a reflecting speculum of parabolic form. But it was Newton,
about 1666, who first made a reflecting telescope; and he did it with
the object of avoiding colour dispersion.

Some time elapsed before reflectors were much used. Pound and Bradley
used one presented to the Royal Society by Hadley in 1723. Hawksbee,
Bradley, and Molyneaux made some. But James Short, of Edinburgh, made
many excellent Gregorian reflectors from 1732 till his death in 1768.