The American house-carpenter; a treatise on the art of building, and the strength of materials (1873)
Hatfield, R. G. (Robert Griffith), 1815-1879 · New York : J. Wiley · leaf 65
118.— To describe an ellipsis by intersection of lines. 7 Lei Ri) PRACTICAL GEOMETRY. a b and c d, (Fig. 83,) be given axes. Through c draw / «-,parallel tc a b ; from a and 6, draw a /and b g, at right anglnsto a 6 ; divide f a, g b, a e and e 6, each into a like number ofequal parts, as at 1, 2,… … Where neither trammel nor string is at hand, this, perhaps, Isthe mcst ready method of drawing an ellipsis. The divisionsshould be small, where accuracy is desirable. By this method,an ellipsis may be traced without the axes, provided that a diame-ter and its conjugate be given. Thus, a b and c d,…
Carpentry · Architecture
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