ler--"

"There you go again, Ned. Let's not talk about it. Come on forward and
see what progress we are making."

It must not be supposed that to get the big gun aboard the vessel,
arrange for a new supply of the explosive, and for many of the great
projectiles, had been easy work. It was a task that taxed the skill and
strength of Tom and his friends to the utmost.

There had been wearying delays, especially in the matter of making the
disappearing carriage. At times it seemed as if the required
projectiles would never be finished. The powder, too, gave trouble, for
sometimes batches would be turned out that were utterly worthless.

But Tom never gave up, even when it seemed that some of the failures
were purposely made. Ned declared that there was a conspiracy against
his chum, but Tom could not see it that way. It was due to a
combination of circumstances, he insisted.

But finally the gun had been put aboard the ship, having been
transported from the proving ground in the valley, and they were now en
route to Panama. There the giant cannon was to be set up, and tried
again. If it came up to expectations it was to be finally adopted as
the official gun for the protection of the big canal, and Tom would
receive a substantial reward.

"And I'm confident that it will make good," said the young inventor to
his chum, as they paced the deck of the vessel. "In fact, I'm so sure I
have practically engaged the Universal Steel Company to hold itself in
readiness to make several more of the guns."

"But suppose Uncle Sam decides against the cannon on this second test?"

"Well, then I've lost out, that's all," declared Tom, philosophically.
"But I don't believe they will."

"It certainly is a giant cannon," remarked Ned, as he paused to look at
the prostrate monster, lashed to the deck, with its wrappings of
tarpaulins. "It looks bigger here than it did when you fired the shot
that saved the town, Tom."

"Yes, I suppose it does, by contrast. But let's go down and see how the
powder and shells are standing the trip. I told the captain to have
them securely lashed, so if we struck rough weather, and the vessel
rolled, they wouldn't carry away."

"Especially the powder," put in Ned. "If that starts to banging
around--well, I'd rather be somewhere else."

"Bless my rain gauge!" cried Mr. Damon. "Please don't say such things.
You make me nervous. You're as bad as that steel foreman."

"All right, I'll be better," pro