So with dredges, with steam shovels, and hydraulic pumps, that sucked through big flexible pipes mud and water, spraying it off to one side, the work went on.  Blake had Mr. Alcando to help him, and the Spaniard was now expert enough to render valuable assistance.  While Blake was at one scene, getting views of the relief work, his pupil could be at another interesting point.

Blake had telegraphed to New York that the one picture above all others desired had been obtained—­that of a big slide in the Culebra Cut.  He did not tell how Joe had nearly lost his life in helping get the films, for Blake was modest, as was his chum, and, as he said, it was “all in the day’s work.”

Joe was left to recover from the shock and slight injuries at Gatun, while Blake and Mr. Alcando were at Culebra.  For the shock to the young moving picture operator had been greater than at first supposed, though his bodily injuries were comparatively slight.

“Well, what’s next on the programme?” asked Joe of Blake, about two weeks after the accident, when Blake had returned from Culebra.  Most of the work there was done, and the Canal was again open, save to vessels of extreme draught.

“I guess we’ll go on making pictures of Gatun Dam now; that is, if you’re well enough,” spoke Blake.  “How do you feel?”

“Pretty fair.  How did Alcando make out?”

“All right.  He’s learning fast.  We can trust him with a camera now, out alone.”

“That’s good.  I say, Blake,” and Joe’s voice took on a confidential tone, “you haven’t noticed anything strange about him, have you?”

“Strange?  What do you mean?”

“I mean while he was off there with you.  Anything more about that alarm clock of his?  And did anything more develop about his knowing the captain of that vessel that sunk the Nama?”

“No, that was only coincidence, I think.  Why, I can’t say that I’ve noticed anything suspicious about him, Joe, if that’s what you mean,” and Blake’s voice had a questioning tone.

“That’s what I do mean,” spoke Joe.  “And if you haven’t I have.”

“Have what?”

“I’ve been watching Alcando since you and he came back, and I think he’s decidedly queer.”

“Suspicious, you mean?”

“I mean he acts as though something were going to happen.”

“Another landslide?” asked Blake with a laugh.  “No chance of that here at Gatun Dam.”

“No, but something else could happen, I think.”

“You mean the—­dam itself?” asked Blake, suddenly serious.

“Well, I don’t exactly know what I do mean,” Joe said, and his voice was troubled.  “I’ll tell you what I noticed and heard, and you can make your own guess.”

“Go on,” invited Blake.  “I’m all ears, as the donkey said.”

“It’s no laughing matter,” retorted his chum.  “Haven’t you noticed since you and Alcando came back,” he went on, “that he seems different, in a way.  He goes about by himself, and, several times I’ve caught him looking at the dam as though he’d never seen it before.  He is wonderfully impressed by it.”