Appleton's dictionary of machines, mechanics, engine-work, and engineering : illustrated with four thousand engravings on wood ; in two volumes (1873)
D. Appleton and Company · New York : D. Appleton and Co. · leaf 622
There is another precaution of more importance, which consists of having always at hand in thelight-room a spare lamp, trimmed and adjusted to the height for the focus, which may be substitutedfor the other in case of accident. It ought to be noticed,liowever, that it takes about twenty minutesfrom…
Mechanical engineering · Mechanics · Engineering
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