To determine the bevel or slant of the top cross-bar so that the piece shown in Fig. 1 shall be fitted as in Fig. 2, draw (Fig. 3) to scale as shown. Along a horizontal line mark off the span of the greenhouse to 1 in. to the foot say, as indicated by A; then draw the vertical line shown at B, and mark off the amount of fall (that is the difference between the height of the front and back) to the same scale. Then the line C represents the correct fall. The end view of the rail can now be marked out full size as shown at D E F, and the triangular piece scored shows the amount of material to be taken off. A gauge may be set to the distance G II, and the wood marked by it; or a bevel can be set as indicated by the dotted lines, and the woo 1 plane:! to suit it in the ordinary manner.

Fig. 3. Shaping- the Top Rail of Greenhouse.