"Isn't it wonderful!" exclaimed his daughter with enthusiasm; and Linton nodded. "Wonderful, indeed, yet here it is!"
Her father went on stolidly: "It was proved many years ago that a flying machine weighing nearly 8,000 lbs., carrying its own engine, fuel, and passengers, can lift itself into the air. An aeroplane will always lift a great deal more than a balloon of the same weight."
"I know," agreed Linton, "and it can travel at a high rate of velocity with less expenditure of power."
"Exactly; a well-made screw propeller obtains sufficient grip on the air to propel an air-boat at almost any speed; the greater the speed the greater the efficiency of the screw. We are going slowly at this moment, but I could put her along at 70 miles an hour, if one wanted to."
Suiting the action to the word, he did increase the speed very considerably for a short distance, and conversation had to be suspended. It was the quickest travelling Linton had yet experienced in the upper air, and he turned with some anxiety to Zenobia Jardine, thinking the pace might tax her nerves. She was perfectly calm, however, and her father set all fears at rest by saying, as he slackened pace again:
"The steering with the new gyroscope is almost automatic, just as if she were a torpedo. Even in a stiff wind she reverts to a horizontal keel. It is simply like the balancing of a bird."
"The Bladud is splendid!" cried Linton with conviction.
"She's hard to beat," was the President's comment. "But, after all, she's only the natural outcome of the air-gun, which has been known for generations. An air-gun is shaped like a rifle, with a hollow boiler or reservoir of power. You force into the reservoir by means of a condensing syringe as much air-power as it will hold. By opening a valve a portion of the air escapes into the barrel of the gun. That's what takes place when you pull the trigger. The released air presses against the ball just as gunpowder would. Off goes your bullet without a sound or sign to show that it has been discharged. Air condensed to 1-46th of its bulk gives about half the velocity of gunpowder. It's precisely the same principle that's firing us through the air at the present moment."
"It's a wonderful discovery!" was Linton's comment.
"Yes," mused Mr. Jardine, "and yet the thing was always there to be discovered."