nd if after this the block exhibits any defects situated at most difficult part of the apparatus such a depth that they cannot be to construct. The glass was cast at the Jeumont Works, and a special removed, it is submitted to a mold- furnace was constructed capable of ing which changes its form… … 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 establish- After this comes another heating and cooling which tripoli and as…
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