“Yes, and there may be again,” said Blake.

“I hope not!” exclaimed Captain Watson.  “They are not only dangerous, but they do terrible damage to the Canal and the machinery.  We want no more slides.”

“But some are predicted,” Blake remarked.

“Yes, I know they say they come every so often.  But now it would take a pretty big one to do much damage.  We have nearly tamed Culebra.”

“If there came a big slide here it would block the Canal,” observed Mr. Alcando, speculatively.

“Yes, but what would cause a slide?” asked the captain.

“Dynamite could do it,” was the low-voiced answer.

“Dynamite?  Yes, but that is guarded against,” the commander said.  “We are taking no chances.  Now, boys, you get a good view of Culebra,” and he pointed ahead.  Blake and Joe were soon busy with their cameras, making different sets of views.

“Hand me that other roll of film; will you, please?” asked Blake of the Spaniard, who was helping them.  “Mine is used up.”

As Mr. Alcando passed over the box he muttered, though possibly he was unaware of it: 

“Yes, dynamite here, or at the dam, would do the work.”

“What—­what’s that?” cried Blake, in surprise.

CHAPTER XVI

THE COLLISION

Judging by Mr. Alcando’s manner no one would have thought he had said anything out of the ordinary.  But both Blake and Joe had heard his low-voiced words, and both stared aghast at him.

“What’s that you said?” asked Blake, wondering whether he had caught the words aright.

“Dynamite!” exclaimed Joe, and then Blake knew he had made no mistake.

Somewhat to the surprise of himself and his chum the Spaniard smiled.

“I was speaking in the abstract, of course,” he said.  “I have a habit of speaking aloud when I think.  I merely remarked that a charge of dynamite, here in Culebra Cut, or at Gatun Dam, would so damage the Canal that it might be out of business for years.”

“You don’t mean to say that you know of any one who would do such a thing!” cried Blake, holding the box of unexposed film that the Spaniard had given him.

“Of course not, my dear fellow.  I was speaking in the abstract, I tell you.  It occurred to me how easy it would be for some enemy to so place a charge of explosive.  I don’t see why the Canal is not better guarded.  You Americans are too trusting!”

“What’s that?” asked Captain Watson, coming up at this juncture.

“I was merely speaking to the boys about how easy it would be to put a charge of dynamite here in the cut, or at the dam, and damage the Canal,” explained Mr. Alcando.  “I believe they thought I meant to do it,” he added with a laugh, as he glanced at the serious faces of the two moving picture boys.

“Well,—­I—­er,—­I—­,” stammered Blake.  Somewhat to his own surprise he did find himself harboring new suspicions against Mr. Alcando, but they had never before taken this form.  As for Joe, he blushed to recall that he had, in the past, also been somewhat suspicious of the Spaniard.  But now the man’s frank manner of speaking had disarmed all that.