Thierry wrote:
snip
Galileo simply improved the design but lenses being very expensive (and they
are always), most lenses show bubble, colors and other artifacts (see the
collection at IMSS, firenze)

The other thing I like about Galileo's telescope is his micrometer that
was attached to the telescope. It was used to measure the angular
positions of Jupiter's moons and the relative angular sizes of planets.
Apparently, a physical copy of the micrometer did not survive. Here's
an interesting simulation of the micrometer.

Simulation of the micrometer attached to Galileo's telescope
Institute and Museum of the History of Science in Florence
http://brunelleschi.imss.fi.it/museum/esim.asp?c=100505
(Right-hand sidebar)

- Canopus56

P.S. for lurkers -

Other pictures of Galileo's telescope at the Institute and Museum of
the History of Science in Florence
http://brunelleschi.imss.fi.it/museum/esim.asp?c=500104

These supplement the excellent photographs at Thierry's site:
http://www.astrosurf.org/lombry/galilee-lunettes.htm