American Stair-Builders' Guide e-bog

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. Make A B (figure 1) the long diameter or major axis, and C D half the short diameter or minor axis of the required ellipse. From the point D as centre, with C B as radius, describe arcs, cutting the major axis at 2 and 3; at the points, place pins; around the pins, place a cord so fastened at the ends that it shall reach around g de; place your pencil inside the cord and describe the ellipse A D B R. Dare should be taken to keep the cord to an even tension. Suppose the elliptic curve A D B to be the centre of a mould required for a wreath, set off each way from D half the width of the rail, and draw the dotted lines D 2 and D 3. From the points S and H draw lines parallel to D 2 and D 8 to intersect the major axis. At the points thus found, place pins and describe the outside and inside curves. To draw two elliptical curves parallel to each other, set ofi' from R to J, equal to B N, from the point J as centre, with C N as radius, describe ares, cutting the major axis at A and B, the points for the pins to describe the curve required.