turn, feed the engines."

"Yes, that's all plain enough," said the inquisitive Dick, "but how do
you get your power for starting?"

"If there is not enough juice in the storage batteries for the purpose
we resort to compressed air," was the reply from Tom, for Jack, with
keen eyes on the unrolling ribbon of road, was too busy to have his
attention distracted.

"And that?" Dick paused interrogatively.

"Is pumped into a pressure tank as we go along. See that gauge?" he
pointed to one on the dashboard of the car in front of the driver's
seat.

Dick nodded.

"Well, that's a pressure gauge. You see, we have sixty pounds of air
in the tank now. That can generate enough electricity to start the car
going. After that the process is automatic."

"Yes, you explained that. Suppose the tank should, through an
accident, be empty, and you wanted to start?"

"We've provided for that"

"I expected so. Wabbling wheels of Wisconsin, you fellows are
certainly wonders."