FIG. 105 is a perspective view of a simple water motor which costs little to make, and can be constructed by anybody able to use carpenter’s tools and a soldering iron. It will serve to drive a very small dynamo, or do other work for which power on a small scale is required. A water supply giving a pressure of 40 lbs. upwards per square inch must be available. We begin operations by fashioning the case, which consists of three main parts, the centre and two sides, held together by brass screws. For the centre, select a piece of oak 1 inch thick. Mark off a square, 7 inches on the side; find the centre of this, and describe a circle 5 inches in diameter. A bulge is given to the circle towards one corner of the square, at which the waste-pipe will be situated. Cut out along the line with a keyhole saw. Then saw out the square of wood. A 5/8-inch hole is now bored edgeways through the wood into the “bulge” for the escape, and in what will be the top edge is drilled a 1/4-inch hole to allow air to enter. [Illustration: FIG. l05.—Simple water turbine.] Cut out the sides, and screw them on to the centre at the four corners, taking care that the grain runs the same way in all three pieces, so that they may all expand or contract in the same direction. Plane off the edges of the sides flush with the centre. The parts should now be separated, after being marked so that they can be reassembled correctly, and laid for a quarter of an hour in a pan of melted paraffin wax, or, failing this, of vaseline, until the wood is thoroughly impregnated. Reassemble the parts, and put in the rest of the holding screws, which should have their heads countersunk flush with the wood.