But that feeling soon wore off, and before a glittering expanse of water in the distance showed them that the ocean lay before them, Ned Nevins, the virtual owner of the Electric Monarch, was at work on the motors, oiling and adjusting as if he had been an engineer of a flying ship all his life.

The motion of the craft was delightfully smooth and even. If it had not been for the furious wind of the propellers, and the roaring of the motor, it would have been difficult to believe they were moving at all. Yet the speed indicator showed that they had attained a velocity of fifty miles an hour and their maximum speed had not by any means been reached.

Jack knew that with new machinery it would have been risking over-heated bearings and all manner of engine trouble, to let the Electric Monarch out to her full capacity.

Jack’s cheeks glowed and his eyes shone as the craft drove onward, with his firm hands on the controlling wheel. It was invigorating and blood-quickening to feel the way in which the Electric Monarch responded instantly to every move of the controlling devices.

“Of course the Electric Monarch isn’t mine, nor have I any right to any share in her but the builder’s, and yet I can’t help feeling that we all have a part in her,” said the boy to himself. “That Jeptha Nevins must have been a wonder. If he had only lived, this would have been a proud day for him. He certainly left Ned a great legacy in those plans. I wonder——”

Jack broke off short in his ruminations. The plans! It was true they were in the safe at High Towers, but it was also true that just the moment before sailing they had learned that enemies were interested in securing them. Enemies backed by powerful interests, too, judging by what Heiny Dill had said.

A troubled look crossed Jack’s face. His father was ill. In case intruders gained access to the library, he could make but a feeble resistance. But the next moment he dismissed the thought as ridiculous. How could any one know where the plans had been placed? And even so, if an attempt was made to blow open the safe, the servants would be bound to hear.

“Just the same,” thought the boy, “I wish we’d notified the police before we started.”

But at that moment a wind flaw struck the Electric Monarch and Jack’s attention was fully occupied in handling the craft as she heeled over like a ship in a heavy sea. When she was once more on an even keel, he had other matters to occupy his mind.