This section is from the book "The American House Carpenter", by R. G. Hatfield. Also available from Amazon: The American House Carpenter.

Draw a b (Fig. 176) through the widest part of the given section, and parallel to c d; bisect a b in e, and through a, e, and b draw h i, f g, and k j at right angles to a b; at a convenfent place on the line f g, as o, with a radius equal to half the width of the cap, describe the circle ijg; make r l equal to e b or e a; join l and j, also l and i; from the curve f b to the line l j draw as many ordinates as is thought necessary parallel to fg; from the points at which these ordinates meet the line l j, and upon the centre, 0, describe arcs in continuation to meet op; from n t x, etc., draw ns,tu, etc., parallel to fg; make ns, t u, etc., equal to ef, wv, etc.; make x y, etc., equal to z d, etc.; make o 2, o 3, etc., equal to o n, o t, etc.; make 2 4 equal to n s, and in this way find the length of the lines crossing o m; through the points thus found describe the section of the newel-cap as shown in the figure.

Fig. 177.

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