"Why, to make one on the principle of the anemometer," replied Ralph.
"How do you spell it?"
"Never mind the spelling, it's like this," and Ralph rapidly sketched out [Fig. 98].
"This is the wind gauge of the weather bureau," he explained, "and I figure we can use ordinary tin cups for the buckets. You go down to the hardware store and buy four small round bottomed tin cups while I start the woodwork."
Having secured the cups for five cents each, they cut the handles with a pair of tinners' "snips." The cut was made next to the cup at the lowest point and the handle straightened out even with the top of the cup.
Two pieces of pine, 16 inches long, 7⁄8-inch wide, and 5⁄8-inch thick, were halved together at the centre, where a 1⁄4-inch hole was bored straight through the joint.
A block of wood cut to the shape a was fitted over the joint, and fastened to the four arms with 1-inch brads. The 1⁄4-inch hole was now continued almost through this cap to give a long bearing for the pivot—a ten-penny wire nail with the head filed off. Two 3⁄16-inch holes were drilled through the handle of each cup and corresponding holes through the wooden arms. The cups were made fast by passing 3⁄16-inch bolts through cup handles and arms and tightening the nuts.
This made a very strong and rigid construction and on testing it by holding the pivot in the hand out in the breeze the instrument revolved rapidly.
Altogether it was one of the most substantial and satisfactory things that they had made, but Ralph was not yet satisfied.
"We might as well have a Coney Island of our own as not," he said. "You whittle out four propellers, 4 inches long and 1⁄2 inch across, and I'll show you something," he said.