But, to his chagrin, he saw them rise the next instant, as cleverly as ever.  Lieut.  Bradbury, who had been watching the maneuver of the Golden Butterfly, gave an admiring gasp, as he witnessed the daring feat.

“Good heavens!” he exclaimed, and the evident note of astonishment and appreciation in his tones did not tend to increase Mortlake’s self-satisfaction.

“The pesky brats,” he muttered to himself; “we’ve got to do something to put them out of the race.  There isn’t another American-built aeroplane that I fear except that bothersome kids’ machine.”

And there and then Mortlake began to hatch up a scheme that in the near future was to come very nearly proving disastrous to Peggy and Roy and their high hopes.

“Magnificently handled, don’t you think so, Mortlake?” inquired the naval officer, the next instant.

“Yes, very clever,” agreed Mortlake, far too smart to show his inward feelings, or to wear his heart upon his sleeve; “very neat.  But I can do the same thing if you’d care to see it?”

The naval officer glanced at the puffy features of his companion and his thick, bull-like neck.

“No, thanks,” he said.  “I’ve got to be getting back.  There’s another type of machine I’ve got to look over out at Mineola.  It is really necessary that I reach there as quickly as possible.”

“Very well,” said Mortlake, inwardly relieved, as he didn’t much fancy duplicating Roy’s feat, “we’ll head straight on for the shore.”

“If you please.”

But what was the Golden Butterfly doing?  As the steamer raced onward, that aerial wonder had swung in a spiral, and was now seemingly hovering about, awaiting the arrival of the Silver Cobweb.

As the two aeroplanes drew abreast, Mortlake muttered something, and bent over his engines.  The Cobweb leaped forward like an unleashed greyhound.  But the Golden Butterfly was close on her heels, and making almost as good time.  Mortlake plunged his hands in among the machinery and readjusted the air valve of the carburetor.  Another increase of speed resulted.  The indicator crawled up to sixty-six, sixty-eight and then to seventy miles an hour.

“Pressing her a bit, aren’t you?” asked the officer, as they seemed to hurtle through the air, so fast did they rush onward.

“Oh, no.  She’s built for speed,” responded Mortlake, with a gratified grin; “she’ll leave any such old lumber wagon as that Prescott machine miles behind her any day in the week.”

This seemed to be true.  The Golden Butterfly, making about sixty miles, was being rapidly left behind.

“I should think you’d be afraid of overheating your cylinders,” volunteered the lieutenant.

Now, this was just what Mortlake was afraid of.  But, as has been said, he was the sort of man who, in sporting parlance, was willing always “to take a chance” to beat any one he considered his rival.  He was taking a desperate chance now.  Under the artificial means he had used to increase the speed of his engines, the motor was “turning up” several hundred more revolutions a minute than she had been built for.