Somewhere within the historic edifice of Paris Observatory , on the banks of River Seine , is stored away , inwards packing crates , simply about of the biggest lenses e'er manufactured. Two of them mensurate 49 inches (1.25 meters) inwards diameter. These lens were i time the most critical components of the largest refracting telescope e'er attempted.
Construction of the Great Paris Exhibition Telescope began inwards 1892 , within months afterward the French regime announced plans for the 1900 World’s Fair inwards Paris. The thought was to build a construction equally impressive equally the Eiffel Tower which was constructed equally the entrance to the 1889 World's Fair. These world’s fair , that were beingness held periodically all over Europe , provided the hosting province , equally good equally participants , the chance to showcase advances they had achieved inwards manufacturing , scientific discipline , as well as technology. Countries would strove for prestige past times exhibiting their latest machines as well as products , their cultural achievements , as well as regal possessions.
The Great Telescope , installed , from the ocular lens end.
Just 3 years agone , French Republic had successfully concluded the 1889 World’s Fair as well as was basking nether its glory when intelligence came that Deutschland was planning an international fair inwards 1896 or mayhap inwards 1900. The intelligence threatened French Republic because they believed that the province which hosted the exposition at the threshold of the novel century volition define the philosophy of the entire nineteenth century to the world. The French regime decided to human activity fast as well as announced the 1900 World’s Fair , simply to seize the initiatory from Germany.
The centerpiece of Exposition Universelle was the Great Paris Exhibition Telescope housed within Palais de l'Optique. The telescope had 2 interchangeable objective lenses 1.25 meters inwards diameter , i for visual observation as well as i for making photographic plates. They had a focal length of 57 meters , as well as the steel underground that housed them was lx meters inwards length. Because of their enormous size as well as weight , the telescope couldn’t endure maneuvered to aim at astronomical objects. Instead , it was mounted inwards a fixed horizontal seat , as well as calorie-free from astronomical objects was redirected into the optical underground assembly via a movable bird mirror organisation , known equally a Foucault siderostat. The telescope’s eyepiece was placed on rails as well as could endure shifted past times 5 feet for focusing. With the lowest ability of 500× , the telescope had a champaign of persuasion of 3 arc minutes.
An engraving of the non bad telescope of the 1900 Paris Exposition universelle , showing an overall persuasion (top); the siderostat (left) as well as lens underground (right); as well as the ocular lens destination (inset)
The telescope was on display for almost a twelvemonth , during which solely a few scientific observations were made. Astronomers watched sunspots as well as nebulas , as well as made large photographs of the surface of the Luna , despite the fact that its location inwards the fairgrounds close powerful as well as vivid lights was non ideal for astronomical observation. In the destination , the telescope turned out to endure largely a gimmick as well as non a serious astronomical instrument. During the fair , thousands of people came to spotter the telescope. They paid a few cents as well as peered through the eyepiece. But non a unmarried buyer came forward.
The companionship which had organized inwards 1886 to build the telescope went bankrupt , as well as the telescope was seat upwards for auction inwards 1909. Still , no i bought it. Eventually , the telescope was broken upwards for fighting as well as the lenses as well as mirror were stored away at the Paris Observatory where they yet remain.
Although the telescope turned out to endure completely useless , equally far equally scientific discipline is concerned , but equally the centerpiece of an exhibition showcasing the best of the recent advances inwards manufacture as well as engineering , it did serve a purpose.
Today , almost all major optical telescopes used for astronomical purpose are reflecting telescope , because reflecting telescopes are non express inwards size as well as technological constraints the means refracting telescopes do. The largest performance refracting telescope is at the Yerkes Observatory , as well as it utilizes xl inch (102 cm) refractor —9 inch less than the Great Paris Exhibition Telescope.
The eye-piece holder
An 1892 cartoon ridiculing François Deloncle’s proposal to "bring the Luna within a meter".
Sources: Wikipedia / Unusual Telescopes past times Peter L. Manly / Gale / Arthur Chandler