The correct wav of getting the true shape of the soffit of splayed framed-up linings, sides and soffit to have the same angle of splay, is the following. Set out the plan and elevation (Figs. 1 and 2), and the section through the centre as shown at Fig. 3. Draw the Horizontal line A B passing through the centre C ot the segment. Produce the section line 1 8 of the soffit until it cuts the line A 15 in D. This is the centre required for the true shape of the soffit. With D as centre and 1 and 8 as radii, draw the arcs 7, 1,14, and 13, 8,15. Now divide half of each of the upper and lower arcs in elevation (Fig. 2) into any number of equal parts as shown, then on the development (Fig. 3) set off distances exactly equal as shown by the corresponding figures. Join 7 to 13: this gives the true shape of the left-hand half of the surface of the soffit; the other half, of course, will be the same. The arcs drawn through E and V (Fig. 3) show the amount of bevelling to each edge. To get the bevel for the top of the jambs (or side linings), with H (Fig. 1) as centre draw the arc K L and project up to M, then project horizontally from 7 to M. Join 31 to 13, which will give the bevel G required, as shown.

Splayed Linings to Segmental Opening.