Tissandier, Gaston, 1843-1899, Frith, Henry, 1840-, Harry Houdini Collection (Library of Congress) DLC · London, New York [etc.] Ward, Lock & Co · leaf 479
of lenses free from colour. Tenyears before (in 1718) Hadley had established the ReflectorTelescope ; Herschel made his celebrated forty-foot re-flector in 1789. However, to resume. In 1747, Euler declared that itwas quite possible to construct an arrangement of lenses soas to obtain a colourless… … Image on the Retina, of iflint, and a convex lens of crown, he corrected the colours.The question of proper curvature was finally settled, andthe Achromatic Telescope became an accomplished fact There are two classes of Telescopes—the reflecting andrefracting. Lord Rosses is an instance of the…
Scientific recreations
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