Plainly it was a gas accumulator or condenser of some kind. It even suggested an attempt to make a device for liquefying gases. The parts were so rusted that even after oiling them, Andy could not operate them.
“I’ll pass that up for to-day,” thought the boy finally, his face wet with perspiration and his hands greasy with oil and brown from the rust. “Now for the little model!”
He had a theory about the cylinders, but he had none about the model. In appearance, it resembled a wooden fan that the boy had once seen—a fan made by slitting half of a bit of straight-grained pine and then spreading the slit sections out like over-lapping feathers. In a way, too, it resembled a bird’s tail. The device to which the fan-like pieces were attached was so contrived as to open and close the tail-like extension.
Andy carried the contrivance into the sunlight and carefully cleaned it. Then, by grasping the central wooden shaft with a pair of pliers, he found he was able to turn it. A little brass cogwheel on the shaft operated in two smaller wheels, one on each side. These, working on a beveled gear, moved levers simultaneously but in opposite directions. It required but a few minutes to discover that turning the shaft to the right drew down the fan-like blades on the right-hand side of the tail-like part and, at the same time, elevated those on the left-hand side.
“I guess it’s a toy,” argued the boy. “Maybe the inside of an automatic bird. Anyway, it works just as a bird spreads its tail when flying.”
Further examining the miniature combination of wood and brass, Andy made another discovery: the shaft not only turned both ways, but it, the beveled gears, and the connecting levers, worked forward and back. As the boy pushed the shaft backward, all the sheaves of the tail-like extension flew upward.
“It is a bird,” exclaimed Andy. “It moves like a pigeon’s tail when the bird starts flying.”
Pulling the shaft forward, reversed the operation, and the sheaves dropped downward.
“There she is comin’ down,” the boy cried aloud. “I’ve got it. It’s a new kind o’ boat rudder.”
What increased the resemblance to a bird’s tail was another ingenious device—two rows of small cones just above and below the narrow ends of the sheaves. Each blade, working upon a universal hinge, was free to move to the right and left. As they rose or fell under the pressure of the shaft, they pressed on the cones and spread out, fanwise.