Yerkes Observatory is the home of the largest refractor ever built: the objective lens is 40 inches in diameter and the telescope tube is over 60 feet long. The mount was made by Warner & Swasey in Cleveland and the optics were ground by the Alvan Clark Company. The observatory building (designed by Henry Ives Cobb) and telescope are outstanding examples of late 19th century architecture and technical achievement. I’d like to thank Richard Dreiser of the Yerkes staff for his help with this project.
