Page 402 - 89 history of astronomy_opt

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 con-
vex object-glass and a concave eye-lens, and
this type is spoken of as the Galilean tele-
scope. 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
402