or have spokes.  This wheel is used to attach wires for guying.  The bottom pin in the center pole is placed in a hole that is bored into a block of wood about 12-in. square and 3 or 4 in. thick.  A piece of sheet metal should be drilled and placed on the pin between the block and end of the pole to make a smooth bearing.  The center pole is now placed in position and guyed with six wires that are about 35 ft. long.  Stakes are driven into the ground and the wires fastened to them and to the wheel at the top end of the pole.  Care should be taken when attaching the wires to get the center pole to stand perpendicular.  Twelve hooks should be placed at equal distances around the center pole about 1 ft. from the top end.  Wires are fastened to these hooks and to the twelve 2 by 4-in. pieces used for the spokes.  The wires should be tied around each spoke about 2 ft. from the ends.  Space the spokes with equal divisions and cover the outer 2 ft. of the ends with boards, as shown in the plan sketch on the right hand end of the drawing.  The boards may be nailed or bolted.  If bolted and the wires made in a loop at the hooks, the swing can easily be taken apart and changed from one place to another.  —­Contributed by A. O. Graham, Fort Worth, Tex.

** Home-Made Arc Lamp [132]

The frame of the lamp is made from bar metal 3/4 in. wide and 1/8 in. thick, bent and welded to make a continuous loop in the shape as shown at G in the sketch.  This frame should be about 10-1/2 in. long with the upper or wider part 4 in. long, and the lower part 6-1/2 in. long.  The width should be about 5-1/4 in. at

[Illustration:  Arc Lamp]

the top and 4 in. at the bottom.  A cross bar, L, made of the same material, is fitted into the off-set in the frame and riveted.  Holes are drilled through the frame and brass bushings, H and J, are fitted for bearings to receive the adjusting brass rod, B, which should be 1/4 in. in diameter.  A brass curtain rod can be used for the rod B, and on its lower end a socket, P, is soldered.

A piece of brass 2 in. long, 1/2 in. wide and 1/8 in. thick is used for the armature, A, to be operated by the magnet coil, C. The coil, C, is made in the usual manner by wrapping No. 14 cotton-covered magnet wire on a wooden spool that has a soft iron core.  The spool is about 2-1/2 in. long.  The armature, A, is drilled, making a hole just a little larger than the rod, B, and is adjusted in place by two set screws, D and E. A soft piece of iron, F, is fastened to the opposite end of the armature with a screw, which should be placed directly under the end of the coil’s core.  This end of the armature may be kept from swinging around by placing it between a U-shaped piece of brass fastened to the cross piece L. At the bottom end of the frame, and directly centering the holes H and J, a hole is drilled to receive a hard rubber bushing, R, for insulating the brass ferrule, S, that holds the lower carbon.