Hatfield, Robert Griffith, 1815-1879. [from old catalog] · New York & London, Wiley and Putnam · leaf 60
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 ah ; from a and 6, draw a / and h g, at right anglesto ab ; divide f a, g b, ae and e 6, each into a like number ofequal parts, as at 1, 2, 3 and… … 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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