Side-lights on astronomy and kindred fields of popular science; essays and addresses (1906)
Newcomb, Simon, 1835-1909 · New York Harper · leaf 102
ESCOPE so that the strokes of the polisher shall cross the lensin all directions. This double motion insures everypart of the lens coming into contact with every partof the polisher, and moving over it in every direction. Then whatever parts either of the lens or of thepolisher may be too high to… … GRINDING A LARGE LENS is slid back and forth over the lens by means of acrank attached to a revolving wheel. The polisheris at the same time slowly revolving around a pivotat its centre, which pivot the crank works into, andthe glass below it is slowly turned in an opposite di-rection. Thus the…
Astronomy
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