“One of the secret agents brought me the box containing the mechanism that was to set off the dynamite,” the Spaniard resumed.  “You nearly caught him,” he added, and Blake recalled the episode of the cigar smoke.  “I had secret conferences with the men engaged with me in the plot,” the conspirator confessed.  “At times I talked freely about dynamiting the dam, in order to throw off the suspicions I saw you entertained regarding me.  But I must explain one thing.  The collision, in which the tug was sunk, had nothing to do with the plot.  That was a simple accident, though I did know the captain of that unlucky steamer.

“Finally, after I had absented myself from here several times, to see that all the details of the plot were arranged, I received a letter telling me the dynamite had been placed, and that, after I had set it off, I had better flee to Europe.”

Blake had accidentally seen that letter.

“I received instructions, the time we were starting off on the tug,” went on Alcando, “that the original plot was to be changed, and that a big charge of dynamite was to be used instead of a small one.

“But I refused to agree to it,” he declared.  “I felt that, in spite of what I might do to implicate myself, you boys would be blamed, and I could not have that if the Canal were to suffer great damage.  I would have done anything to protect you, after what you did in saving my worthless life,” he said bitterly.  “So I would not agree to all the plans of that scoundrel, though he urged me most hotly.

“But it is all over, now!” he exclaimed with a tragic gesture.  “I am caught, and it serves me right.  Only I can be blamed.  My good friends, you will not be,” and he smiled at Blake and Joe.  “I am glad all the suspense is at an end.  I deserve my punishment.  I did not know the plot had been discovered, and that the stage was set to make so brilliant a capture of me.  But I am glad you boys had the honor.

“But please believe me in one thing.  I really did want to learn how to take moving pictures, though it was to be a blind as to my real purpose.  And, as I say, the railroad company did not want to really destroy the dam.  After we had put the Canal out of business long enough for us to have amassed a fortune we would have been content to see it operated.  We simply wanted to destroy public confidence in it for a time.”

“The worst kind of destruction,” murmured Captain Wiltsey.  “Take him away, and guard him well,” he ordered the soldiers.  “We will look further into this plot to-morrow.”

But when to-morrow came there was no Mr. Alcando.  He had managed to escape in the night from his frail prison, and whither he had gone no one knew.

But that he had spoken the truth was evident.  A further investigation showed that it would have been impossible to have seriously damaged the dam by the amount of dynamite hidden.  But, as Captain Wiltsey said, the destruction of public confidence would have been a serious matter.