The setting out shown in Fig. 318 is for an outlet fitting on the underside of a pipe, but the method of laying out the pattern will be exactly the same if the case is that of a hopper resting on top of the pipe. Fig. 318.

Geometrically this is the intersection of a pyramid and a cylinder.

In striking out the patterns the point B is obtained by drawing the line B K square to K C, and making it equal to K L, the point A being fixed in a similar manner. Now, using C as centre and C B as radius an arc is swung around, and on this three full widths each equal to K 3 cut off. The two outside lengths are each bisected, as it will be seen that the pattern is for making the article up in two pieces. The curve passing through H on the pattern can be set out by first getting the middle point F of D E and then cutting C G off equal to C F; fixing H by making C H equal to C D; drawing a line through G at right angles to G C, and by the trammel method (Chapter XXI (Elliptical Work. Construction Of Ellipse).) constructing the part ellipse M H N. The major axis of the ellipse will, of course, be E D, and the minor axis the diameter of the pipe.

The hole is shown marked out by projection; the girth being measured from the end elevation along the arc 0 to 3. It could manifestly be set out in any position, the lengths of construction lines being taken by measurement across the circle in the end elevation.