[Illustration:  Wiring Diagram]

(metallic circuit) of telegraph where a telephone may be used in combination on the line.  The telephone receivers can be used both as receivers and transmitters, or ordinary telephone transmitters, induction coils and battery may be used in the circuit with a receiver.  If a transmitter is used, its batteries may be connected in circuit with a common push button which is held down when using the telephone.  On a 1000-ft. line, four dry cells will be sufficient for the telegraph instruments and two cells for the telephone.  —­Contributed by D. W. Milter.

** How to Make a Miniature Windmill [333]

The following description is how a miniature windmill was made, which gave considerable power for its size, even in a light breeze.  Its smaller parts, such as blades and pulleys, were constructed of 1-in. sugar pine on account of its softness.

The eight blades were made from pieces 1 by 1-1/2 by 12 in.  Two opposite edges were cut away until the blade was about 1/8 in. thick.  Two inches

[Illustration:  Details of Miniature Windmill Construction]

were left uncut at the hub end.  They were then nailed to the circular face plate A, Fig. 1, which was 6 in. in diameter and 1 in. thick.  The center of the hub was lengthened by the wooden disk, B, Fig. 1, which was nailed to the face plate.  The shaft C, Fig. 1, was 1/4-in. iron rod, 2 ft. long, and turned in the bearings detailed in Fig. 2.  J was a nut from a wagon bolt and was placed in the bearing to insure easy running.  The bearing blocks were 3 in. wide, 1 in. thick and 3 in. high without the upper half.  Both bearings were made in this manner.

The shaft C was keyed to the hub of the wheel, by the method shown in Fig. 3.  A staple, K, held the shaft from revolving in the hub.  This method was also applied in keying the 5-in. pulley F, to the shaft, G, Fig. 1, which extended to the ground.  The 2-1/2-in. pulley, I, Fig. 1, was keyed to shaft C, as shown in Fig. 4.  The wire L was put through the hole in the axle and the two ends curved so as to pass through the two holes in the pulley, after which they were given a final bend to keep the pulley in place.  The method by which the shaft C was kept from working forward is shown in Fig. 5.  The washer M intervened between the bearing block and the wire N, which was passed through the axle and then bent to prevent its falling out.  Two washers were placed on shaft C, between the forward bearing and the hub of the wheel to lessen the friction.

The bed plate D, Fig. 1, was 2 ft. long, 3 in. wide and 1 in. thick and was tapered from the rear bearing to the slot in which the fan E was nailed.  This fan was made of 1/4-in. pine 18 by 12 in. and was cut the shape shown.  The two small iron pulleys with screw bases, H, Fig. 1, were obtained for a small sum from a hardware dealer.  Their diameter was 1-1/4 in.  The belt which transferred the power from shaft C to shaft G was top string, with a section of rubber in it to take up slack.  To prevent it from slipping on the two wooden pulleys a rubber band was placed in the grooves of each.