Paul mounted to a height of about two thousand feet, then let the Sky-Bird straighten out in the direction of their next stop. He opened up the throttle little by little, and the machine rapidly gained momentum. But somehow the young pilot was dissatisfied. Finally he hitched the stick over to the notch which should have brought the craft into a speed of 150 miles, and watched the speedometer closely.
"Humph!" he ejaculated, after fifteen or twenty minutes.
"Say, Paul," cried Bob just then, "we're losing on the Clarion.
She's clear out of sight now."
"Why don't you tell me something I don't know?" growled Paul in a tone very queer for him.
"What's the matter with you, Buddy?" demanded John, stepping up. "You seem to have an awful grouch on, some way!"
"Got a good reason for it," snapped Paul. "This is enough to make a preacher almost swear."
"Don't talk, but speed her up a bit if you don't want them to get away," advised John.
"She doesn't act right, somehow," said Paul. "The Sky-Bird ought to be hitting it up to a hundred and fifty right now, but she's only making a hundred and fifteen. She acts groggy; don't you notice it?"
"I thought myself she was riding a little rocky—sort of out of balance," admitted John.
"Take the stick and try her yourself," said his brother.