Davies, Charles, 1798-1876 · New York, Cincinnati [etc.] American book company · leaf 248
es; the de-grees are numbered from 0 to 360. At the 0 point, and at the opposite extremities of thediameter passing through that point, are small lines on theinner edge of the Hmb ; the two extremities of the diameter,perpendicular to this latter, are designated in the same way. Two angular pieces… … Pig. 131. a, 5, c, and d, move them in the directions of the lines ab, cd,fcr the purpose of bringing the steel pins exactly into the linewhich passes through the 0 of the index and the centre ofthe protractor. To adjust them to their places, place the centre of the pro-tractor oyer a marked point,…
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