Hatfield, Robert Griffith, 1815-1879. [from old catalog] · New York & London, Wiley and Putnam · leaf 58
fg and g f, show tha position of the string when the pencil arrives at g. This method, when performed correctly, is perfectly accurate;but the string is liable to stretch, and is, therefore, not so good tonse as the trammel. In making an ellipse by a string or twine,that kind should be used which… … Fig. 81 116.— The axes being given, to describe an ellipsis with atrammel. Let a b and c d, {Fig. 81,) be the given axes. Placethe trammel so that a line passing through the centre of thegrooves, virould coincide with the axes ; make the distance fromthe pencil, e, to the nut,/^ equal to half c d ;…
Carpentry · Architecture
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