Figure 185 shows a detail of the boom. Cut the side sticks H 18 inches long, and fasten between them the separators I, which should be just long enough to allow clearance for the spool pulley J. The pulley is mounted on the axle K. Screw the lower ends of the boom to the mast, at a point 2½ inches above the base.
The Windlass for raising the derrick boom, and for hoisting the loads, is shown in detail in Fig. 186. Bore a hole through upright L for the axle M to stick through, and cut axle M enough smaller than the spool drums N so they will turn easily. Fasten a crank and handle to one end of each spool, and drive a brad through each end of the axle to prevent the drums from sliding off. Cut four notches in the inner flange of each spool, as shown, and pivot the catches O to the post L, in the positions indicated, so they may be thrown into the notches to lock the windlass (Fig. 176).
Fig. 186.—Detail of Derrick Windlass.
The Hoisting Cables should be made of strong cord. Fasten one end of the cable for raising the boom to a nail (P, Fig. 176), and run this cord up and over the mast pulley, then down through screw-eye G and over to one drum; tie it securely to the drum so it will not slip around. The other cable should be fastened between the nut and
