For a short space there was a calm that seemed more thrilling than the wildest confusion. It took a few seconds for the rush of water to reach the Bohio, and when it did the tug began to sway and tug at the mooring cables, for they had not yet been cast off to enable it to be towed.

Blake rushed toward the lower cabin.

"Where are you going?" cried Joe.

"To get the cameras," replied his chum, not pausing. "This is a chance we mustn't miss."

"But we must escape! We must look to ourselves!" shouted Mr. Alcando. "This is not time for making moving pictures."

"We've got to make it this time!" Joe said, falling in with Blake. "You'll find you've got to make moving pictures when you can, not when you want to!"

To do justice to Mr. Alcando he was not a coward, but this was very unusual for him, to make pictures in the face of a great danger—to stand calmly with a camera, turning the crank and getting view after view on the strip of celluloid film, while a flood of water rushed down on you. It was something he never dreamed of.

But he was not a "quitter," which word, though objectionable as slang, is most satisfactorily descriptive.

"I'll help!" the young Spaniard cried, as he followed Blake and Joe down to where the cameras and films were kept.

On came the rush of water, released by the accidental opening of the upper lock gates before the lower ones were closed. The waters of Gatun Lake were rushing to regain the freedom denied them by the building of the locks.

But they were not to have their own way for long. Even this emergency, great as it was, unlikely as it was to happen, had been foreseen by those who built the Canal.

"The dam! Swing over the emergency dam!" came the cry.

The Bohio was now straining and pulling at her cables. Fortunately they were long enough to enable her to rise on the flood of the rushing water, or she might have been held down, and so overwhelmed. But she rose like a cork, though she plunged and swayed under the influence of the terrible current, which was like a mill race.

"Use both cameras!" cried Blake, as he and Joe each came on deck bearing one, while Mr. Alcando followed with spare reels of film. "We'll both take pictures," Blake went on. "One set may be spoiled!"

Then he and his chum, setting up their cameras on the tripods, aimed the lenses at the advancing flood, at the swung-back gates and at the men on top of the concrete walls, endeavoring to bring into place the emergency dam.

It was a risky thing to do, but then Blake and Joe were used to doing risky things, and this was no more dangerous than the chances they had taken in the jungle, or in earthquake land.

On rushed the water. The tug rose and fell on the bosom of the flood, unconfined as it was by the restraining gates. And as the sturdy vessel swayed this way and that, rolling at her moorings and threatening every moment to break and rush down the Canal, Blake and Joe stood at their posts, turning the cranks. And beside them stood Mr. Alcando, if not as calm as the boys, at least as indifferent to impending fate.

Captain Wiltsey of the Bohio had given orders to run the engine at full speed, hoping by the use of the propeller to offset somewhat the powerful current. But the rush of water was too great to allow of much relief.

"There goes the emergency dam!" suddenly cried Blake.

"Gone out, you mean?" yelled Joe above the roar of waters.

"No, it's being swung into place. It'll be all over in a few minutes. Good thing we got the pictures when we did."

Across the lock, about two hundred feet above the upper gate, was being swung into place the steel emergency dam, designed to meet and overcome just such an accident as had occurred.

These dams were worked by electricity, and could be put in place in two minutes; or, if the machinery failed, they could be worked by hand, though taking nearly half an hour, during which time much damage might be done. But in this case the electrical machinery worked perfectly, and the dam, which when not in use rested against the side of the lock wall, and parallel with it, was swung across.

Almost at once the rush of water stopped, gradually subsiding until the tug swung easily at her mooring cables.

"Whew!" whistled Blake in relief, as he ceased grinding at the crank of his moving picture camera. "That was going some!"

"That's what!" agreed Joe. "But I guess we got some good films."

"You certainly deserved to!" exclaimed Mr. Alcando, with shining eyes. "You are very brave!"

"Oh, it's all in the day's work," spoke Blake. "Now I wonder how that happened?"

"That's what I'd like to know," said Captain Wiltsey. "I must look into this."

An inquiry developed the fact that a misplaced switch in some newly installed electrical machinery that controlled the upper lock gate was to blame. The lock machinery was designed to be automatic, and as nearly "error proof" as anything controlled by human beings can be. That is to say it was planned that no vessel could proceed into a lock until the fender chain was lowered, and that an upper gate could not be opened until a lower one was closed. But in this case something went wrong, and the two gates were opened at once, letting out the flood.

This, however, had been foreseen, and the emergency dam provided, and it was this solid steel wall that had saved the lock from serious damage, and the Bohio from being overwhelmed.

As it was no harm had been done and, when the excitement had calmed down, and an inspection made to ascertain that the gates would now work perfectly, the tug was allowed to proceed.

"Well, what are your plans now, boys?" asked Mr. Alcando on the day after the lock accident.

"Back to Culebra Cut," answered Blake. "We have orders to get a picture of a big slide there, and we're going to do it."

"Even if you have to make the slide yourself?" asked the Spaniard with a short laugh.

"Not much!" exclaimed Blake. "I'd do a good deal to get the kind of moving pictures they want, but nothing like that. There have been some rains of late, however, and if things happen as they often have before in the Cut there may be a slide."

"Yes, they do follow rains, so I am told," went on the Spaniard. "Well, I do not wish your Canal any bad luck, but if a slide does occur I hope it will come when you can get views of it."

"In the daytime, and not at night," suggested Joe.

For several days nothing of interest occurred. Blake and Joe sent back to New York the films of the mad rush of waters through the lock, and also dispatched other views they had taken. They had gone to Culebra Cut and there tied up, waiting for a slide that might come at any time, and yet which might never occur. Naturally if the canal engineers could have had their way they would have preferred never to see another avalanche of earth descend.

Mr. Alcando had by this time proved that he could take moving pictures almost as well as could the boys. Of course this filming of nature was not all there was to the business. It was quite another matter to make views of theatrical scenes, or to film the scene of an indoor and outdoor drama.

"But I do not need any of that for my purpose," explained Mr. Alcando. "I just want to know how to get pictures that will help develope our railroad business."

"You know that pretty well now," said Blake. "I suppose you will soon be leaving the Canal—and us."

"Not until I see you film the big slide," he replied. "I wish you all success."

"To say nothing of the Canal," put in Joe.

"To say nothing of the Canal," repeated the Spaniard, and he looked at the boys in what Blake said afterward he thought was a strange manner.

"Then you haven't altogether gotten over your suspicions of him?" asked Joe.

"No, and yet I don't know why either of us should hold any against him," went on Joe's chum. "Certainly he has been a good friend and companion to us, and he has learned quickly."

"Oh, yes, he's smart enough. Well, we haven't much more to do here. A slide, if we can get one, and some pictures below Gatun Dam, and we can go back North."

"Yes," agreed Blake.

"Seen anything of Alcando's alarm clock model lately?" asked Joe, after a pause.

"Not a thing, and I haven't heard it tick. Either he has given up working on it, or he's so interested in the pictures that he has forgotten it."

Several more days passed, gloomy, unpleasant days, for it rained nearly all the time. Then one morning, sitting in the cabin of the tug anchored near Gold Hill, there came an alarm.

"A land slide! A big slide in Culebra Cut! Emergency orders!"

"That means us!" cried Blake, springing to his feet, and getting out a camera. "It's our chance, Joe."

"Yes! Too bad, but it had to be, I suppose," agreed his chum, as he slipped into a mackintosh, for it was raining hard.