Davies, Charles, 1798-1876 · New York, Cincinnati [etc.] American book company · leaf 166
s be moved ineither direction by working thescrews with an adjusting-pin.Across the flat surface of the ringtwo fine fibres of spiders web, or,better, very fine platinum-wire, are extended at right angles to each other, their ends being cementedinto fine lines cut in the metal of the ring. The… … 160 ELEMENTS OF SURVETIl^G. [BOOK IV. The openiugs in the telescope tube are made considerablylarger than the screws, so that, when these are loosened, the ringmay be moved a short distance in the direction of the length ofeither wire for purposes of adjustment as hereafter described, andmay also…
Surveying
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