't anything. When
I was perfecting my giant cannon I was nearly blown up more than once,
and you remember how we got stuck in the submarine."

"I should say I did!" exclaimed Ned with a shudder. "I don't want any
more of that. But as between being blown through a roof and held at the
bottom of the sea, I don't know that there's much choice."

"Well, perhaps not," agreed Tom. "But as for ending my experiments, I
wouldn't dream of such a thing! Why, I've only just begun! I'll have a
silent motor yet!"

"And a non-explosive one, I hope," added Mr. Damon dryly. "Bless my
shoe buttons, Tom, but if my wife knew what danger I'd been in she'd
never let me come over to see you any more."

"Well, the next time I invite you to a test I'll be more careful,"
promised the young inventor.

"There isn't going to be any next time as far as I'm concerned!"
laughed Ned. "I think it's safer to sell Liberty Bonds."

And, though they joked about it, they all realized the narrow escape
they had had. As for Eradicate, once he knew he had not been the one
who caused the damage, he felt rather proud of the part he had taken in
the mishap, and for many days he boasted about it to Koku.

True to his determination, Tom Swift did not give up his experimental
work on the silent motor. The machine that had been blown through the
roof was useless now, and it was sent to the scrap heap, after as much
of it as possible had been salvaged. Then Tom got another piece of
apparatus out of his store room and began all over again.

He worked along the same lines as at first--providing a chamber for the
escaping gases of the exhaust to expend their noise and energy in, at
the same time laboring to cut down the concussion of the explosions in
the cylinder without reducing their force any. And that it was no easy
problem to do either of these, Tom had to admit as he progressed. All
previous types of mufflers or silencers had to be discarded and a new
one evolved.

"Jackson, I need some one to help me," said Tom to his chief
mechanician one day. "Haven't you a good man who is used to
experimental work that you can let me take from the works?"

"Why, yes," was the answer. "Let me see. Roberts is busy on the new
bomb you got up, but I could take him off that--"

"No, don't!" interposed Tom. "I want that work to go on. Isn't there
some one else you can let me have?"

"Well, there's a new man who came to me well recommended. I took him on
last week, an