"Great!" exclaimed the eccentric man. "Bless my postage stamp, but it's great! Why, there's hardly a sound, Tom, and I can hear you quite easily."
"And I can hear you," added Tom. "I don't believe, down below there," and he nodded toward the earth, though Mr. Damon could not see this, as the airship, save for a tiny light over the instrument board, was in darkness, "they know that we're flying over their heads."
"I agree with you," was the answer. "Tom, my boy, I believe you've solved the trick! You have produced a silent aeroplane, and now it's up to the government to make use of it."
"I'm not quite ready for that yet," replied the young inventor. "I have several improvements to make. But, when they are finished, I'll let Uncle Sam know what I have. Then it's up to him."
"And you must be careful, Tom, that some of your rivals don't hear of your success and get it away from you," warned Mr. Damon, as Tom guided the Air Scout along the aerial way—an unlighted and limitless path in the silent darkness.
"Oh, they'll have to get up pretty early in the morning to do that!" boasted Tom, and afterward he was to recall those words with a bit of chagrin.
On and on they sailed, and as Tom increased the speed of the motor, and noted how silently it ran, he began to have high hopes that he had builded better than he knew. For even with the motor running at almost full speed there was not noise enough to hinder talk between himself and Mr. Damon.
Of course there was some little sound. Even the most perfect electric motor has a sort of hum which can be detected when one is close to it. But at a little distance a great dynamo in operation appears to be silence itself.
"I can go this one better, though," said Tom as he sailed along in the night. "I see where I've made a few mistakes in the baffle plate of the silencer. I'll correct that and—"
As he spoke the machine gave a lurch, and the motor, instead of remaining silent, began to cough and splutter as in the former days.