here is a nice old photo from the smithsonian institute showing George Van Biesbroeck at yerkes observatory in wisconsin, USA, with the world's largest refracting telescope.
i used to run public viewing nights with old 9 inch refractor on UT-Austin's campus. it was clearly not as large as the one at yerkes, but it was really fun to use because it had no electronics. the old beast only followed the rotation of the stars because of a mechanical clock drive hanging inside its mount structure!
|Photo Credit: Smithsonian Institute|