Howe, Herbert A. (Herbert Alonzo), 1858-1926 · Meadville, Penna., Flood and Vincent · leaf 144
he heat thus com-municated to thelens raises an intol-erable lump in it,which will not dis-appear till that por-tion of the glass hascooled again. A zone which is elevated three or fourmillionths of an inch must not be neglected. The final shaping of the lens ordinarily involves the Final… … Fig. 72.—John A. Brashear, Optician, ofAllegheny, Pa. 138 A Study of the Sky. Placed in a cell. The mounting. The earths rotation counteracted. An odd axis. The finished object-glass is put into a cast-iron cell ;the edges of the two lenses composing the object-glassdo not touch the cast-iron ;…
Astronomy
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