Light signals: A discussion of the optic
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C.O. Harrington Jr.
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Article
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1914
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Elsevier Science
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English
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THE corrugated lens is generally used for signal lights on account of its cheapness, small weight, and more uniform cross-section . Where colored glass is used a fairly uniform cross-section is desirable, as otherwise the centre of the lens would be decidedly darker than the periphery. The corrugate