Water wheels and sandmills may be made from bottle caps and can lids. Two push-in or friction-top can lids are soldered together to form a flanged wheel and bottle caps are soldered between the flanges, at equal intervals, for the buckets. The general construction is shown in Fig. 91. A nozzle may be formed from a piece of tin and soldered to the standard so that a hose may be connected with it and to faucet, or, the water wheel may be set in a sink under a faucet or placed in a stream of running water.

A funnel or sand hopper may be made of tin and soldered to a standard which holds the bucket wheel. Fine dry sand placed in the hopper will run through the hole in the bottom and cause the bucket wheel to revolve.

A Simple Steam Turbine and Boiler.—A very simple and amusing steam turbine that runs with steam generated in a tin-can boiler may be made from tin cans. Select a well-soldered can with a tight-fitting lid, such as a molasses or syrup can with a friction-top lid. The lid will have to be soldered in place to make it steam tight.

Punch a hole about ¼ inch in diameter near one side of the lid for a filler hole. See that this hole is perfectly round so that a cork may be fitted in to make it steam tight.

The vane wheel should be about 3 inches in diameter and very carefully made. See that the axle is soldered exactly in the center of the wheel. The vanes should be small and numerous and each one exactly the same size. The method of construction is shown on page 183 (full page drawing). A 3-inch circle is carefully laid out on a flat piece of tin and then another circle is laid off inside the first one about ¾ inch in. The outer circle is then divided up into 36 equal parts. Draw straight lines from each dividing dot at the edge to the center of the wheel. Bore a small hole exactly where each line crosses the inner circle. Cut down each dividing line to each hole. Use the pliers to turn each vane at right angles to the face of the wheel.

The steam nozzle should be very small. A triangular piece of tin may be formed around a fine wire nail or pin. The opening in the nozzle should be about ?32 inch in diameter. The nozzle should be well soldered together and then soldered to the boiler, over a hole of a suitable size to allow the steam to flow from the boiler into the nozzle. Be sure not to solder up the tube so that the steam may not escape. A piece of broom straw may be placed in the nozzle when soldering it together, and it may be left in when the nozzle is soldered to the boiler. The straw should extend into the boiler and may be withdrawn when the soldering operations are completed. Do not use wire inside the nozzle to prevent it filling with solder as the solder will stick to it and prevent its being withdrawn.

Use care in placing the nozzle in position under the vane wheel so that the steam will strike the vanes squarely when it escapes. Set the end of the nozzle as close to the vanes as possible, but so that it does not strike the vanes when the wheel revolves.

These turbines run at very high speed when carefully made. Do not use too much heat under the boiler, as too great pressure may explode it with disastrous results. If the boiler is set over a gas flame, take care not to allow the flame to flare out around the boiler and creep up the sides, as it may then melt off the top of the boiler even when there is considerable water in it. A moderate flame will cause enough pressure to be generated in the boiler to make the vane wheel revolve rapidly. If care is used in fitting the cork in the filler hole, it may be made steam tight by pushing it into the filler hole with a light pressure so that if too much pressure is generated in the boiler the cork will blow out.

A pinion from a small clock works may be soldered to the vane wheel shaft and meshed in with a large gear which is set on a shaft soldered to the supporting upright at one side of the wheel. A small pulley may be made of wood or metal and fastened to the large gear. This arrangement of gears will give a reduced speed and a string belt may be run from the pulley to some light running toy machine. The pinion and gear fastened to the turbine should run very easily.

An alcohol heating lamp may be made for the turbine boiler by soldering a wick tube and a vent tube to a shoe paste or salve box.

The wick tube should be made from a strip of tin rolled up into a cylindrical shape. It should be about ½ inch in diameter and 1½ inches in length when soldered together. The wick tube should extend about 1 inch above the top of the lamp and it should be soldered firmly in a hole cut in the top of the lamp to receive it.

A small tube about ¼ inch in diameter and 3 inches long is soldered together. This tube should be soldered over a hole near the side of the lamp at the top and soldered on at an angle as shown in Fig. 91. It serves as a vent, allowing the alcohol gas generated within the top of the lamp to escape and it also serves as a handle. An alcohol lamp fitted with a vent tube of this description will not boil over and catch fire as so many of the small alcohol lamps provided with toy steam engines are sure to do. Vent tubes soldered to these lamps in such a manner as to conduct the gas away from the flame will provide against accidents of this sort.

A filler hole should be placed in the top of the lamp as far away from the wick tube as possible. A common cork may be used as a stopper. A small funnel may be easily made from some pieces of scrap tin and used for filling the boiler and the lamp.

A Windmill and Tower.—A windmill and tower that will look very realistic when completed may be made from tin cans. The vane wheel is composed of twelve blades set in two can lids. The vanes are cut from a flat piece of tin, care being taken to make each one exactly the same size. A large can lid is used for the outer vane support and the central part of this lid is cut away. Twelve cuts are made around the edge of the can lid at equal distances and the vanes soldered in these cuts.

A small can lid is used for the center of the wheel and the ends of the vanes soldered to it.

The tower is made of strips of folded tin and the tank from a tin can is shown in Fig. 92.

Aeroplane Weathervane.—A biplane weathervane may be made from flat strips of tin. Large round or square cans may be opened out and the tin taken from them used to make the aeroplane weathervane. When this weathervane is mounted on a suitable spike on which it may turn about freely in the wind, the propeller will revolve rapidly when the wind blows.

The construction of the aeroplane is quite simple and the principal dimensions are given in Fig. 93. The construction is very well shown in Plate XVIII. If the foregoing problems have been satisfactorily worked out there will be no difficulty in constructing the aeroplane from the dimensions given.

The two wings are made from two pieces of tin of the required size with the edges folded over.

The body of fuselage is made of a long triangular piece of tin folded up on each side so as to form a sort of long tapering box. A cover is made for this box and divided into two parts so as to leave a cockpit opening.

The struts or wing supports are made from narrow strips of tin that are folded almost together for strength. The small guy wires had best be made from copper wire of small diameter. If it is difficult to get small copper wire, it may be possible to get two or three feet of insulated copper wire used for electrical purposes. Such wire is employed to wind small magnets used on electric bells. The insulation easily burns off. Copper wire solders very easily.

The rudder and tail planes are made from flat pieces of tin. A straight piece of wire is used for the propeller shaft. A tube is made of tin and used as a bearing for the shaft. The propeller shaft should fit very loosely in the tube. The bearing tube is soldered firmly to the body of the aeroplane as shown in Fig. 93. When completely assembled, except for the propeller and its shaft, the propeller is soldered to one end of the shaft. Care should be taken to mount the propeller blade in such a way that the shaft is exactly in the center, so that one side of the propeller is not heavier than the other. The shaft is pushed through the bearing tube and should project about ¼ inch beyond it. A strip of tin is wound around this projecting end of the shaft and soldered to it in such a manner that the shaft is free to turn in the tube.

When the plane is completely assembled try it to find the point at which it balances when rested on the finger under the fuselage. A hole should be punched at this point large enough to admit the iron rod or piece of heavy wire that is to be used for the spike on which to mount the weathervane. A second hole is punched directly above the first one; this hole is considerably smaller than the hole beneath it. The top of the iron spike that supports the aeroplane weathervane is filed down to a smaller diameter so that when the spike is pushed through the larger hole the smaller or filed part of the spike will go through the hole in the upper part of the fuselage. The weathervane will then rest on the shoulder formed on the spike as shown in the illustration. A block of wood may be nailed to the roof peak of the house or barn and a hole bored into it the size of the supporting spike, and the spike may be pushed into this and the aeroplane weathervane mounted on the spike. It should be well painted in bright colors and if well made will prove a very pleasing toy.