ving been found among those in the furnace it 14,740 pounds. A weight of 220 pounds is sufficient to is removed and placed upon a car. Slabs of glass are sawed from two parallel sides in order to obtain polish- actuate the clockwork. The mirror has a diameter of 6"56 feet; it is 10p63 ed surfaces… … a special train carried it there Finally, when the glass is very pure SECTIONAL VIEW OF MIRROR-GRINDING APPARATUS. without stopping. A crane de- and perfect another and final mold- posited the gigantic block on a ing produces the plano-convex lens. wagon, and it was carried to the optical…
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