If the frames and other fittings have been properly set up, the cableway will support a sail car, shown in [Fig. 7], or a two-cell electric car, driven by a small motor, as shown in [Fig. 8]. The sailing-car arrangement is often feasible, since a stiff breeze is common in gorges, cañons, narrow valleys, or even in ravines where such a cableway might be set up. The hanger is an H-frame having the grooved pulleys bolted in it, and further reinforced by small blocks at the ends. A braced frame, supporting a deck on which a mast is set, is suspended from the hanger by four curved wires, as shown in the side view, Fig. 7. A sail with boom and gaff is supported by the mast. It is arranged to be shifted around the mast, which is accomplished automatically at the end of a run, or “tack,” by means of the trigger device shown in the top view. The sail is controlled in relation to the wind much as is the main sheet of a sailboat. The car can be operated in this manner only at right angles to the direction of the wind, or nearly so. For play purposes, a boy stationed at each end of the cableway can shift the sail, but the trigger device shown makes this unnecessary. A rubber band is attached to the boom, as indicated in the top view, and a cord and wire are arranged to engage a trigger. A stop for the trigger is fixed to the A-frame so that it is sprung when the car reaches the end of the run. The rubber band reverses the sail, the car having been set on the cable originally so that the forward end is in proper relation to the wind.
Fig. 8
The Electric Car Is Self-Contained and may be Reversed Automatically, if the Motor Is of the Reversible Type, by Contact of the Lever with the Stop Fixed to the A-Frame
The electric car is especially interesting in that it provides self-contained motive power by means of a battery of dry cells, and a motor belted to the hanger, as shown in [Fig. 8]. The hanger is of the H-frame type with heavy blocks between the sidepieces to provide for the small grooved driving pulley set on the axle of one of the larger pulleys. A wooden deck, supported by four heavy wires set into the center block of the hanger, carries the motor, and the dry cells are fixed under it. The motor is of the small reversible battery type, and should be provided with a reversing lever. This will make it possible to reverse the car when it reaches the end of its course. The motor and cells should be disposed so as to balance, tests being made for this purpose before setting them in place finally. A cord or small leather belt connects the drive pulley of the motor with the proper pulley on the hanger. These pulleys should be in line, and that on the hanger should be five times the diameter of the one on the motor shaft. The power is shut off at the end of the course by a shut-off switch which strikes a stop crank attached to the A-frame. When the reversing lever and stop are used, the stop crank is unnecessary. A nonreversing motor can be made to drive the car in a reverse direction by removing the belt from the motor pulley and replacing it to make a figure-eight twist.
¶When babbitt metal is heated some of the tin and antimony in it is burned out, making it unsuited for use in machinery bearings, and similar purposes, after several heatings. The oxidation of the metal is indicated by the formation of a scum on the surface.
A Miniature Fighting
Tank
That Hurdles Trenches
By EDWARD R. SMITH
Among the engines of war in action on land, probably none has created greater interest than the now famous “fighting tank,” which, according to reports, pours out missiles of destruction on the enemy from armored turrets, and crawls over trenches, shell craters, and similar obstructions, like a fabled giant creature of prehistoric ages. The tank described in this article, while not as deadly as those on the battle fields of Europe, performs remarkable feats of hurdling trenches, and crawling over obstructions, large in proportion to its size. The model, as shown in the [heading sketches], is full-armored, and has a striking resemblance to these war monsters. The turret is mounted with a magazine gun, which fires 20 projectiles automatically, as the tank makes its way over the rough ground. The motive power for the tractor bands is furnished by linked rubber bands, stretched by a winding drum and ratchet device, on the rear axle, as shown in [Fig. 1]. When the ratchet is released, the rear axle drives the fluted wheels on it, and they in turn drive the tractor bands, as shown in the side elevation, [Fig. 6]. The wire-wrapped flywheel conserves the initial power of the rubber-band motor, and makes its action more nearly uniform.
The tank will run upward of 10 ft. on the rubber-motor power, depending on the size and number of the bands used. The gun is fired by a spring hammer, actuated by a rubber band. The trigger device is shown in [Fig. 1]. The pulley A is belted, with cord, to the front axle. Four pins on its inner side successively engage the wire trigger, drawing it out of the gun breech B, and permitting another shell to drop into place. As the pulley revolves, the trigger is released, firing the projectile. This process goes on until the motor runs down, or the supply of shells is exhausted.