“A bully good thing to know,” assented Andy.  “For we can be dead sure of Felipe all the time; and through him get pointers about the rest of the crew.  There are a few goats among the sheep, and when we make sure of it, I’m just going to pay them off, and chuck them ashore in any old place.”

“Now that’s what I call a clever scheme,” Frank declared.  “They would have no kick coming, because, you see, no Spanish American could ever complain of getting his wages without having to do any work!”

“I guess not,” Andy remarked, grinning assent.

Upon further conference it was decided to divide the day and night into watches, so that one of them could be on deck and alert all of the time, while the other secured some sleep.

Treachery, they knew, would be likely to crop out during the night time.  Those on board may have found some means of telling their confederates ashore about what time the boat would reach a given point.  And by means of some native method of telegraphing, such as by means of wigwag flags, or “smokes,” the news could be hurried up the river much in advance of the vessel that was butting against the strong current of the swollen Magdalena.

Then Frank went forward to have a long talk with the trusty pilot.  He took Felipe into his confidence, telling him for the first time all about their sacred mission to this region of Colombia.  And in this way, as well as by promising to double his regular wages, Frank quite won the old fellow’s heart.

In return Felipe was able to give his employer considerable valuable information connected with the crew.  Frank mentioned no names, and hence he was satisfied that he had made no mistake in his calculations, when among the list of “suspects” given by the pilot, both Enrique and little “Cospita” were included.

“We must get rid of them both as soon as possible,” he announced.  “So just before night sets in, draw the boat to shore near some village or town.  Then I shall pay both men off, get their signatures to the fact, and insist on their going ashore.  Meanwhile, as you find opportunity, post a few of the faithful ones to the fact that we suspect them of being insurrectoes.”

Felipe declared that the idea was superb.  He was growing more and more fond of these venturesome young Americanos, who were so generous, so brave, and who had come all this great distance, actuated by such a noble purpose.  So many a man may easily feel when his salary has been unexpectedly doubled.

During the balance of that afternoon the two young aviators continued to alternately sit upon the deck, and wander about the boat, watching things.  Frank had the precious aeroplane locked up in the spacious lazerette, which being also used as a storeroom for extra supplies, that the circumstance need not be looked upon as singular.

“I’m determined that no ill may happen to that machine, if I can help it,” he said to his chum, when speaking of what he had had done.