Part 22 (1/2)

It was rather a crude pump, but it did all the work we required of it.

As the wheel went around the crank shaft would move the piston up and down. Whenever the piston went down, the air in the pipe would press up the edges of the leather disk and squeeze past (see Fig. 295). Then when the piston came up again, the leather disk, being backed by the wooden disk beneath it, was kept flat, so that no air could force its way back into the pipe. This made a partial vacuum in the pipe, and the water from the well rushed up through the valve at the bottom to fill it (see Fig. 296). When next the piston went down the bottom valve closed and more air forced its way past the piston. Then on the next upward stroke more water flowed into the pipe, until, after a number of strokes, all the air was pumped out and the water which took its place began to force its way up past the piston and eventually to flow out of the spout into the cask.

Our old windmill was sold to a farmer near Lumberville when we broke camp that fall. We carted it over and set it up for him. A number of years later I saw it still faithfully at work pumping water for his cattle. The original pump had been worn out and a new one subst.i.tuted, but otherwise the old windmill remained just as we had first rigged it up.

[Ill.u.s.tration: Fig. 295. Fig. 296. Action of the Pump.]

CHAPTER XXIV.

THE GRAVITY RAILROAD.

”About all we lack now,” said Dutchy, when the windmill had been completed, ”is a railroad.”

”Then suppose we build one,” was Bill's unexpected rejoinder.

We all thought he was joking, but he wasn't.

”I don't mean a steam railroad,” he said, ”but a gravity railroad.”

”A what?”

”A gravity railroad. Oh, you know what that is--a roller toboggan--the kind they have down at Coney Island.” And he went on to explain how we could rig up a simple roller toboggan on our island.

His plan was to build an inclined trestle on the high ground just below the lagoon, and then run wooden tracks along the sh.o.r.e down to the pontoon bridge, and across the mill-race to Kite Island. We started first to dig a road down to the bridge, because the bank was quite high at this point. The task was rather greater than we antic.i.p.ated, but we kept steadily at it until we had cut a fairly good road through the bank, though the grade was rather steep.

Before proceeding with the trestle and track we thought the best plan would be to build our car, and then we could use it as a gauge to determine how far apart the rails should be set.

THE CAR.

[Ill.u.s.tration: Fig. 297. Putting the Car Body Together.]

First we got a 2 x 4-inch scantling, and cut from it two lengths, each 4 feet 6 inches long. These were laid on edge just 30 inches apart, and then a number of boards were nailed across from one scantling to the other and sawed off flush with their edges. The floor thus formed was now turned over so that the scantlings lay uppermost and the sides of the car were then nailed on with their edges overlapping the ends of the floor boards. The sides, which were about 18 inches high, were each made of two boards firmly battened together. Great care was taken to securely nail both the flooring and the sides to the scantlings, because these scantlings were to carry the wheels of the car. The car body was completed by nailing on the end pieces which overlapped both the flooring and the side walls.

THE f.l.a.n.g.eD WHEELS.

[Ill.u.s.tration: Fig. 298. The Car Wheel.]

Next we sawed out the wheels of our car. From a board of hardwood 3/4 of an inch thick four disks, 12 inches in diameter, were sawed out. Then from a board 1 inch thick four 9-inch disks were sawed out. We cut these disks in the same way as we had made the disks for our surveying rod (see page 78), by making cuts across corners and finally smoothing off the angles with a draw-knife. A half-inch hole was now drilled in the center of each disk. Then on each large disk a smaller one was placed, with the center holes of the two coinciding and the grain of one lying across the grain of the other. In this position they were firmly nailed together, making a wheel like those used on a railway car, with the small disc forming the tread of the wheel and the large disk serving as a f.l.a.n.g.e.

THE CAR AXLES.

[Ill.u.s.tration: Fig. 299. Car Body with Axles in Place.]

For the car axles we bought four 1/2-inch bolts, 6 inches long, with two washers and two nuts for each bolt. In each side of the car, about 8 inches from the ends, we nailed face blocks; that is, blocks of wood for the wheels to bear against. These face blocks were only 1/2 inch thick.