Page:Tom Swift and His Motor Cycle.djvu/66

Rh. He had finally to appeal to his father, in order to get the right proportion between the back and front gears, for the motor-cycle was operated by a sprocket chain, instead of a belt drive, as is the case with some.

Mr. Swift showed Tom how to figure out the number of teeth needed on each sprocket, in order to get an increase of speed, and as there was a sprocket wheel from a disused piece of machinery available, Tom took that. He soon had it in place, and then tried the motor. To his delight the number of revolutions of the rear wheel were increased about fifteen per cent.

"I guess I'll make some speed," he announced to his father.

"But it will take more gasolene to run the motor; don't forget that. You know the great principle of mechanics—that you can't get out of a machine any more than you put into it, nor quite as much, as a matter of fact, for considerable is lost through friction."

"Well, then, I'll enlarge the gasolene tank," declared Tom. "I want to go fast when I'm I going."

He reassembled the machine, and after several hours of work had it in shape to run, except that a front wheel was lacking.