"I'll write and ask him," answered the lad "I'm sure he'll go."
Securing, a few days later, the assistance of two mechanics, whom he knew he could trust, for as yet the construction of the Advance was a secret, Mr. Swift prepared to rush work on the submarine, and for the next three weeks there were busy times in the shed next to the seaside cottage. So busy, in fact, were Tom and Mr. Sharp, that they only found opportunity for one trip in the airship, and that was to get some supplies from the shops at home.
"Well," remarked Mr. Swift one night, at the close of a hard day's work, "another week will see our craft completed. Then we will put it in the water and see how it floats, and whether it submerges as I hope it does. But come on, Tom. I want to lock up. I'm very tired to-night."
"All right, dad," answered the young inventor, coming from the darkened rear of the shop. "I just want to"
He paused suddenly, and appeared to be listening. Then he moved softly back to where he had come from.
"What's the matter?" asked his father in a whisper. "What's up, Tom?"
The lad did not answer. Mr. Swift, with a
