For several days after the first real trial of his sky racer Tom was busy going over the Humming-Bird, making slight changes here and there. He was the sort of a lad who was satisfied with nothing short of the best, and though neither his father nor Mr. Jackson could see where there was room for improvement, Tom was so exacting that he sat up for several nights to perfect such little details as a better grip for the steering-lever, a quicker way of making the automatic equilibriumizer take its position, or an improved transmitter for the wireless apparatus.
That was a part of his monoplane of which Tom was justly proud, for though many aeroplanes to-day are equipped with the sending device, few can receive wireless messages in mid-air. But Tom had seen the advantage of this while making a trip in the ill-fated Red Cloud to the cave of the diamond makers, and he determined to have his new craft thus provided against emergencies. The wireless outfit of the Humming-Bird was a marvel of compactness.
Thus the days passed, with Tom very busy; so busy, in fact, that he hardly had time to call on Miss Nestor. As for Andy Foger, he heard no more from him, and the bully was not seen around Shopton. Tom concluded that he was at his uncle's place, working on his racing craft.
The young inventor sent a formal protest to the aviation committee, to be used in the event of Andy entering a craft which infringed on the Humming-Bird, and received word from Mr. Sharp that the interests of the young inventor would be protected. This satisfied Tom.
Still, at times, he could not help wondering how the first plans had so mysteriously disappeared, and he would have given a good deal to know just how Andy got possession of them, and how he knew enough to use them.
"He, or some one whom he hired, must have gotten into our house mighty quickly that day," mused Tom, "and then skipped out while dad fell into a little doze. It was a mighty queer thing, but it's lucky it was no worse."
The time was approaching for the big aviation meet. Tom's craft was in readiness, and had been given several other trials, developing more speed each time. Additional locks were put on the doors of the shed, and more burglar-alarm wires were strung, so that it was almost a physical impossibility to get into the Humming-Bird's "nest" without arousing some one in the Swift household.
"And if they do, I guess we'll be ready for them," said Tom grimly. He had been unable to find out who it was that had attempted once before to damage the monoplane, but he suspected it was the ill-favored man who was working with Andy.
As for Mr. Swift, at times he seemed quite well, and again he required the services of a physician.
"You will have to be very careful of your father, Tom," said Dr. Gladby. "Any sudden shock or excitement may aggravate his malady, and in that case a serious operation will be necessary."