[Drawn for this work by L. W. TRUESDELL, Tinman, Owego, N. Y.]

Fig. 13.

From C as a centre, describe a circle whose diameter will be equal to the width of the boiler outside of the wire, and draw the line AB perpendicular to the line EF, having it pass through the point I>, which is one-half of the length of the boiler; then mark the point J one quarter of an inch or more as you wish, for the pitch of the cover, and apply the corner of the square on the line AB, allowing the Made to fall on the circle at H, and the tongue at the point .J; then draw the lines HB, BJ, CA and AJ, which completes the description.