y heard unusual noises, but
it was only some disturbance caused by the storm, and morning
arrived without anything unusual having taken place. The rain still
continued, and Tom, looking from his window and seeing the downpour,
remarked:

"I'm glad of it!"

"Why?" asked his father, who was in the next room.

"Because I'll have a good excuse for staying in and working on my
motor-cycle."

"But you must do some studying," declared Mr. Swift. "I will hear
you in mathematics right after breakfast."

"All right, dad. I guess you'll find I have my lessons."

Tom had graduated with honors from a local academy, and when it came
to a question of going further in his studies, he had elected to
continue with his father for a tutor, instead of going to college.
Mr. Swift was a very learned man, and this arrangement was
satisfactory to him, as it allowed Tom more time at home, so he
could aid his father on the inventive work and also plan things for
himself. Tom showed a taste for mechanics, and his father wisely
decided that such training as his son needed could be given at home
to better advantage than in a school or college.

Lessons over, Tom hurried to his own particular shop, and began
taking apart the damaged motor-cycle.

"First I'll straighten the handle-bars, and then I'll fix the motor
and transmission," he decided. "The front wheel I can buy in town,
as this one would hardly pay for repairing." Tom was soon busy with
wrenches, hammers, pliers and screw-driver. He was in his element,
and was whistling over his task. The motor he found in good
condition, but it was not such an easy task as he had hoped to
change the transmission. 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 a