The American house carpenter: a treatise upon architecture, cornices and mouldings, framing, doors, windows and stairs. Together with the most important principles of practical geometry (1852)
Hatfield, R. G. (Robert Griffith), 1815-1879 · New York, J. Wiley · leaf 62
118.— To describe an ellipsis by intersection of lines. Let PRACTICAL GEOMETRY. 45 a b and c d, {Fig. 83,) be given axes. Through c, draw f g,parallel to a b ; from a and b, draw a / and b g, at right anglesto ab ; divide f a, g b, a e and e 6, each into a like number ofequal parts, as at 1, 2, 3… … Where neither trammel nor string is at hand, this, perhaps, isthe most 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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