A close inspection of the heavier-than-air machine designed by Joe Gresson proved of absorbing interest, for here again celludine entered into the greater part of its construction. Possessed of two planes, these were supported by girders passing to right and left, and braced together in a manner which made them peculiarly rigid, while the lower and upper planes were supported on the girders holding those positions respectively, some three feet only separating them. Immediately beneath, forming, in fact, the foundation for the girders, was a long, boat-shaped body, with sharpened prow, no visible keel, and a flat bottom tapering from stem to stern. The latter extended a considerable distance, and supported at its end two small elevating planes and a big vertical rudder. Finally, two struts on either side had spring wheels attached to them, while the steel stampings, to which they were bolted themselves, had a form of spring attachment which one could realize would provide against severe shocks when landing.
"Then she can come down on water or on land?" asked the Colonel, adjusting an eyeglass which he had just produced. "Most interesting. And how, pray, does she return to her parent ship, this gigantic air vessel?"
"How? By merely circling above and dropping on this deck. I will show you," said Joe, his face flushed with pride. "But first allow me to describe the method by which the pilot controls the machine, and how lateral and fore-and-aft stability are assured. See, there are the same movements as on other machines for controlling height, for turning, or 'banking', to use the technical expression. One merely sits in the cab placed towards the stem of the boat body where the levers are located. Come, Colonel, and you too, Major, and Dick. Try a spin. I can assure you that there is no risk in the matter."
"But—but set off when ten thousand feet from the land, when one can distinguish no single object," cried the former, aghast at such a suggestion. "Yes, I'll come," he said a moment later, deliberately screwing his monocle a little tighter into position and looking at the inventor. "You tell me there is no great risk, and hearing that, I accept the invitation. After all, you must not blame me if I show some little trepidation. My dear sir, I am not a bird, and this is the first occasion on which I have ever ascended from native earth."
As for the Major, he too nodded his willingness, though he also felt not a little trepidation. As for Dick, one may say that the happy-go-lucky fellow hardly ever counted risks, such is the record of midshipmen. But even so, a glance through the transparent material beneath him towards the brown blur far, far below caused him an undoubted tremor. But he had grit. He had proved it, and now leaped into the boat without further hesitation. The Colonel and his brother officer were already there, while Joe stepped in behind them.
"Take your seats, gentlemen," he said, with a smile which went far to reassure them. "Now, we are ready, save for the fact that our engine is not yet running, while the doors of this sunken hangar are not open. But I pull this cord hanging overhead. See! An electric motor raises the whole shed and opens it. Then we press this little pedal—more electricity, my friends—a six-volt battery feeds a small motor aboard here and turns the engine round. Now air is forced through my paraffin carburettor and the vapour resulting is fed to that gasometer in the bows of the boat. Yes, it's a gasometer, just as you see on land, though much smaller. Thence the gas passes to the engine, where it receives more air and—ah! she's off. Listen to her humming, and for one moment notice the position of the engine. It is centrally placed, immediately beneath the planes, and is suspended from a single point. Thus it is free to swing both backward and forward and from side to side. There lies the secret of automatic stability. Say we are coasting along and a gust cants us to the right. The heavy engine still keeps in the same vertical position, while this whole machine turns as it were on that single point. You can readily follow that certain levers attached to engine and machine will be altered in position, and as a direct result the wing tips are warped in a prearranged manner, the back planes rotate upward or downward, or the rudder itself is operated. That is for coasting, for use when on a long, straight flight, when one wishes to take note of one's surroundings, to eat, or even to sleep."
"Sleep!" gasped the Major.
"Why not?" came Joe's cool answer.
"But up in the air, thousands of feet up!"
"As well there as within a hundred feet. The action I have been describing is automatic. There is no question of human error in its behaviour. So long as the planes have room for manœuvring, and the engine does not stop, there is no need to interfere in the slightest. Set your course, lock your tiller, and go to sleep. But you shall see; for the moment I will trust to my own skill in manœuvring. In fact, by pulling this small lever I secure the engine. In effect it is now suspended not only from a single point, but fixed rigidly to the framework of the whole machine. Then if I wish to bank, no automatic action can disturb my calculations. We are ready, I think. Look! flexible tubes above the engine carry the water from the force pumps to the motors on the hubs of the two propellers. There you see precisely the same hydraulic system of conveying power as is used elsewhere in this airship. No need, therefore, to have a dozen men holding the machine down, for the propellers are motionless, the bypass being full open. But I close it now—watch them twirl. I shut it almost completely——"