MAKE A MEME View Large Image ReflectingTelescope 017.jpg Largest disk of optical glass created in the United States as of 1928 The mold for this disk was specifically designed for this purpose and was at the same time a carefully insulated annealing furnace provided ...
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Keywords: ReflectingTelescope 017.jpg Largest disk of optical glass created in the United States as of 1928 The mold for this disk was specifically designed for this purpose and was at the same time a carefully insulated annealing furnace provided with electrical heating elements for controlling the temperatures during cooling The glass was poured at 2400 degrees Fahrenheit Eight months were required for cooling and annealing The disk weighed about 4 000 pounds was 11 inches thick and made from borosilicate crown glass It was intended for use at the Perkins Observatory of Delaware Ohio National Institute of Standards and Technology National Institute of Standards and Technology PD-USGov-NIST PD-USGov National Bureau of Standards National Institute of Standards and Technology Reflecting telescopes Telescope mirrors
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