"Sit still!" cried Tom, and at that instant he tilted the elevation planes, and the craft shot upward, going over the fence like a circus horse taking a seven-barred gate.

"Oh!" exclaimed the physician in a curious voice.They were off on their trip to save the life of Mr.Swift.

What the sensations of the celebrated specialist were, Tom never learned.If he was afraid, his fright quickly gave place to wonder, and the wonder soon changed to delight as the machine rose higher and higher, acquired more speed, and soared in the air over the country that spread out in all directions from Kirkville.

"Magnificent! Magnificent!" murmured the doctor, and then Tomknew that the surgeon was in the grip of the air, and was one of the "bird- men."Every moment the Humming-Bird increased her speed.They passed over the river near where men were working on the broken bridge.It was now no barrier to them.Tom, noting the barograph, and seeing that they were twenty-two hundred feet high, decided to keep at about that distance from the earth.

"How fast are we going?" cried Dr.Hendrix, into the ear of the young inventor.

"Just a little short of a hundred an hour!" Tom shouted back."We'll hit a hundred and five before long."His prediction proved true, and when about forty miles from Shopton that terrific speed had been attained.It seemed as if they were going to have a trip devoid of incident, and Tom was congratulating himself on the quick time made, when he ran into a contrary strata of air.Almost before he knew it the Humming-Bird gave a dangerous and sickening dive, and tilted at a terrifying angle.

"Are we going to turn turtle?" cried the doctor.

"I--I hope not!" gasped Tom.He could not understand why the equilibrium weights did not work, but he had no time then to investigate.Quickly he warped the wing tips and brought the craft up on an even keel.

He gave a sigh of relief as the aeroplane was once more shooting forward, and he was not mistaken when he thought he heard Dr.Hendrix murmur a prayer of thankfulness.Their escape had been a narrow one.Tom's nerve, and the coolness of the physician, had alone saved them from a fall to death.

But now, as if ashamed of her prank, the Humming-Bird went along even better than before.Tom was peering through the slight haze that hung over the earth, for a sight of Shopton.At length the spires of the churches came into view.

"There it is," he called, pointing downward."We'll land in two minutes more.""No time to spare," murmured the doctor, who knew the serious nature of the aged inventor's illness."How long did it take us?""Fifty-one minutes," replied Tom, glancing at a small clock in front of him.Then he shut off the motor and volplaned to earth, to the no small astonishment of the surgeon.He made a perfect landing in the yard before the shed, leaped from his seat, and called:

"Come, Dr.Hendrix!"

The surgeon followed him.Dr.Gladby and Dr.Kurtz came to the door of the house.On their faces were grave looks.They greeted the celebrated surgeon eagerly.

"Well?" he asked quickly, and they knew what he meant.

"You are only just in time," said Dr.Gladby, softly, and Tom, following the doctors into the house, wondered if his trip with the specialist had been in vain.