"By keeping watch. I've got nothing to do now for the next week. We've just set off a big blast, and I've got the powder for the following one all ready. The men will be busy for some time getting out the broken rock. Now what I propose to do is to go in the tunnel and work among them until I can learn something.
"I can understand the language pretty well now, though I can't speak much of it. I'll go in the tunnel every day and find out what's going on."
"But you'll be known, and if one of our men, or one who we suppose is one, turns out to be a spy, he'll be very cautious while you're in there."
"He won't know me," Tom said. "This is how I'll work it. I'll go off with Professor Bumper the next time he starts on one of his weekly expeditions into the woods. But I won't go far until I turn around and come back. I'll adopt some sort of disguise, and I'll apply to you for work. You can tell Tim to put me on. You might let him into the secret, but no one else."
A few days later Tom was seen departing with Professor Bumper into the interior, presumably to help look for the lost city. Mr. Damon was away from camp on business connected with the drug concern, and Koku, to his delight, had been given charge of a stationary hoisting engine outside the tunnel, so he would not come in contact with Tom. It was not thought wise to take the giant into the secret.
Then one day, shortly after Professor Bumper and Tom had disappeared into the forest, a ragged and unkempt white man applied at the tunnel camp for work. There was just the barest wink as he accosted Mr. Titus, who winked in turn, and then the new man was handed over to Tim Sullivan, as a sort of helper.
And so Tom Swift began his watch.