[Illustration:  Valve Motion and Construction of Piston]

The base is made of wood, and has two wood blocks, H and K, 3/8 in. thick, to support bearing B, and valve crank S, which is made of tin.  The hose E connects to the boiler, which will be described later.  The clips FF are soldered to the cylinder and nailed to the base, and the bearing B is fastened by staples.

The valve motion is shown in Figs. 2 and 3.  In Fig. 2 the steam is entering the cylinder, and in Fig. 3 the valve B has closed the steam inlet and opened the exhaust, thus allowing the steam in the cylinder to escape.

The piston is made of a stove bolt, E, Fig. 2, with two washers, FF, and a cylindrical piece of hard wood, G. This is wound with soft string, as shown in Fig. 3, and saturated with thick oil.  A slot is cut in the end of the bolt E, to receive the connecting rod H. The valve B is made of an old bicycle spoke, C, with the nut cut in half and filed down as shown, the space between the two halves being filled with string and oiled.

The valve crank S, Fig. 1, is cut out of tin, or galvanized iron, and is moved by a small crank on the shaft.  This crank should be at right angles to the main crank.

[Illustration:  Engine in Operation]

The boiler, Fig. 4, can be an old oil can, powder can, or a syrup can with a tube soldered to it, and is connected to the engine by a piece of rubber tubing.  The heat from a small gas stove will furnish steam fast enough to run the engine at high speed.  This engine was built by W. G. Schuh and A. J. Eustice, of Cuba, Wis.

** Writing with Electricity [74]

Soak a piece of white paper in a solution of potassium iodide and water for about a minute and then lay it on a piece of sheet metal.  Connect the sheet metal with the negative or zinc side of a battery and then, using the positive wire as a pen, write your name or other inscription on the wet paper.

[Illustration:  Electrolytic Writing]

The result will be brown lines on a white background. 
—­Contributed by Geo. W. Fry, San Jose, Cal.

** To Photograph a Man in a Bottle [74]

Neither a huge bottle nor a dwarfed man is necessary for this process, as it is merely a trick of photography, and a very amusing trick, at that.

First, photograph the person to be enclosed in the bottle against a dark plain background and mark the exact position on the ground glass.  Let the exposure be just long enough to show the figure distinctly.  Then place an empty bottle against a dark background and focus so as to have the outlines of the bottle enclose those of the man.  Let this exposure be about twice the length of the first, and the desired result is obtained.

** A Musical Windmill [74]