Perspective and geometrical drawing adapted to the use of candidates for second and third-class teachers' certificates . Let the concentric circles EF and AB be drawn; drawdiameters AB and CD at right angles to each other, divideeach quadrant into the same number of equal parts, and joinopposite points; draw perpendiculars from the outer pointsand horizontals from the inner points to meet them; thusdraw perpendicular from H and horizontal from a to meetin 1; similarly find 2, 3, 4, etc., all around the circle. Drawa curve through the points of intersection thus found, whichwill form an ellipse
Perspective and geometrical drawing adapted to the use of candidates for second and third-class teachers' certificates . Let the concentric circles EF and AB be drawn; drawdiameters AB and CD at right angles to each other, divideeach quadrant into the same number of equal parts, and joinopposite points; draw perpendiculars from the outer pointsand horizontals from the inner points to meet them; thusdraw perpendicular from H and horizontal from a to meetin 1; similarly find 2, 3, 4, etc., all around the circle. Drawa curve through the points of intersection thus found, whichwill form an ellipse. (Fig. 95.) GEOMETRICAL DRAWING. 125 (6) When the major axis (transverse diameter) only is Let AB be the given diameter; divide it into four equalparts in G, M, D; with centre D and distance^ DG describearc EF, and with centre G and same distance describe arcs tointersect in E and E. Join EG, ED, EG and ED, and producethem to the circumference in C, H, K and L with centre E and distance EC describe arc CH, andwith centre E and distance EK describe arc KL, completingthe elliptical curve. (Eig. 96.) Note.—No part of a true ellipse is an arc of a circle. No. 24—An ellipse being given, to find axis and foci. Draw any two parallel chords AB and CD; bisect eachand join points of section EE, and produce each way tomeet the circumference in G and H; bisect GH in K, andwith centre K describe a circle to cut the ellipse in fourpoints N, O, R and P; join these to form a rectangular paral-lelogram; bisect each side and join the opposite points of sec-tion, and produce both ways to meet circumference in L, M,T and V; then LM and TV will be the axes; and if the dis-
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Keywords: ., bookcentury1800, booksubjectgeometricald, booksubjectperspective
