But he saw the reason a little later, for Alec took him to a sunken deck house, which, seeing that its roof was dead level with the deck, might be expected to offer no resistance whatever to the air. Opening a trap, he ushered his new friend in, though the contents were plainly to be seen without that manœuvre. And there, anchored to the floor, was a pair of spreading planes, as transparent as glass, strong and flexible, attached at their centre to a boat constructed of the same material.
"An aeroplane!" he gasped. "Here, on an airship? Why?"
"For scouting. To act as a messenger. To take passengers to and fro when it's necessary."
Alec spoke loftily, watching Dick's amazement with secret delight. "That's why there are rails on the deck outside," he explained. "She starts from 'em."
"But—but how does she return?" asked Dick, somewhat bewildered, for whoever heard of an aeroplane flying towards an airship and settling upon it? But Alec dismissed the question with a shrug of his shoulders, and a wave of his hands.
"Ain't there enough deck to please you?" he asked. "Do you want to provide a drill ground? You just operate a motor; this sunken hangar rises with the aeroplane, and there you are, ain't you?"
Dick felt the truth of the words. The huge monster on which he had found refuge presented a deck wide enough and long enough to provide safe landing for any aviator. As for this plane upon which he looked, it was obviously meant to float in the water, in fact, it was a waterplane, though the long, centrally-placed boat, to which the planes were immediately attached, was provided with wheels also, to enable it to roll upon the rails, and also to land either on this deck or on terra firma. It was, without shadow of doubt, the last word in the science and manufacture of a heavier-than-air machine.
"Ripping!" exclaimed Dick. "You've been in her?" he asked admiringly, with just a suspicion of jealousy in his voice.
"Once: I'm going again. You'll come too."