Fig. 125b. end view of the engine. d. the crank shaft. e. the rocker arm
Bore a ¹⁄₂ inch hole in the center of the top of the trough; this hole is for the intake port, that is the opening through which the steam flows from the boiler into the steam chest. Bore three ¹⁄₂ inch holes in a line in the middle of the bottom of the trough as is also shown at [A] and [F]. The two holes nearest the ends are the ports to let the steam into and out of the opposite ends of the cylinder, and the central hole, or port, is the exhaust port [C].
Fig. 125c. top view of the engine
Next make the slide-valve; use ¹⁄₈ inch thick wood and make it ³⁄₄ inch high, 1 inch wide, and 1¹⁄₂ inch long on top and 2 inches long on the bottom; the bottom, as you will observe at [A] and [E], is cut out so that it will cover one of the cylinder ports and the exhaust port at the same time and you need put only one side on it.
The slide valve rod is a piece of wood ¹⁄₄ inch in diameter and 11¹⁄₂ inches long. Whittle or plane one end flat and drill a ¹⁄₈ inch hole through it. This done, set the slide valve in the steam chest; slip the slide valve rod through the head and glue it to the slide valve.
Now make four tubes or pipes of cardboard or tin ¹⁄₂ an inch in diameter, and have two of them 1¹⁄₄ inches long and the other two 3 inches long; when you have formed all of them cut a strip ¹⁄₂ inch wide out of each one lengthwise; the purpose of which is to show that they are hollow.
When you have the tubes done glue, or otherwise fix, one of the short ones into the intake port of the steam chest and the other short one into the middle, or exhaust port in the bottom of the steam chest; then glue, or fix the two long tubes into the end holes, or ports, of the steam chest and the holes in the cylinders.
Saw out a guide block for the piston rod to slide through, 2 inches wide, 3 inches high, 3 inches long on top and 5 inches long on the bottom as shown at [A] and [C], and bore a ³⁄₈ inch hole through the middle of the top of it lengthwise so that the center of the hole will be exactly 2¹⁄₄ inches from the base line.