Great Paris Exhibition Telescope of 1900

The Great Paris Exhibition Telescope of nineteen hundred was the largest refracting telescope ever constructed, distinguished by its sixty-meter-long steel tube that had to lie horizontally on the ground. Because of its massive size, the instrument could not be tilted to aim at the sky; instead, a two-meter mirror on a movable siderostat directed light from the heavens into the fixed lens. Housed within the Palais de l’Optique for the World’s Fair, the telescope featured objective lenses over one meter in diameter, designed to bring the Moon within a perceived distance of one meter for the public.