Howe, Herbert A. (Herbert Alonzo), 1858-1926 · Meadville, Penna., Flood and Vincent · leaf 139
ecuting this opera-tion, must not allow the stirrer to touch the pot ; forbits of clay might be ground off and mixed with theglass. The glass is reheated, stirred a second time and evena third time, and returned to the furnace. Every openplace in the furnace is stopped up, so that no air maygain… … Fig. 65.—Lump of Optical Glass. A Great Telescope. 33 .-■^- -v
Astronomy
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