2. Antique Telescopes An overview with photographs of many lesser known telescopes typical of their time. http://www.antiquetelescopes.org/
3. The 28-inch Photo-visual Refractor Exhibition from the Royal Observatory, Greenwich, that explains the history of this telescope via words and archive photographs. http://www.nmm.ac.uk/server.php?request=setTemplate:singlecontent&contentTypeA=conWebDoc&contentId=354&navId=005001004
4. The Astrolabe Ancient astronomical computer. http://www.astrolabes.org/astrolab.htm