The Optics, the Mounting, the Refractor

This chapter describes the stages in the manufacture of optical glass. The fabrication of the huge lenses for the double telescope, for both its visual and photographic objectives, is described. The Grande Lunette with its 83 cm objective remains to this day the largest refracting telescope in Europe and the third largest in the world. The equatorial mounting of the telescope, its tube and driving mechanism are also described.