“It’s a fire, all right, Frank,” he said, as they negotiated the bend, and opened up a new vista ahead.

“Yes, that’s so for a fact,” returned his chum.  “And notice, will you, Andy, how old Felipe has managed to keep over well toward the port shore.  He sized up the situation all right, and knew how to act.”

“Yes, Felipe tells me he used to serve in the army.  Many a battle he has been through, not only in Colombia, but in other countries as well.  He was once something of a soldier of fortune.  But where are you going, Frank?” as his comrade started to leave him.

“I must warn the crew to keep out of sight, or they may be hit, if there happens to be any shooting going on,” called the other, over his shoulder.

He found that every member of the crew seemed to be awake, as if they had talked the situation over, and also guessed where the trouble would lie in wait for the venturesome young Americano senors.

So Frank gave his warning, and saw that they obeyed.  While they were in his employ he felt a certain degree of interest in these ragged fellows, and did not wish to be held responsible for any damage they might receive, if inclined to be reckless at times.

When he once more reached Andy’s side the latter was looking through a pair of marine glasses they had fetched along, thinking they would prove especially valuable in scrutinizing the country over which they might be passing in the aeroplane.

“They’re our friends, the revolutionists, I reckon,” he announced.  “I can see several who carry big swords that dangle around their heels.  And the common soldiers, while they have little if any uniforms, and some of them no shoes, seem to all have guns in their hands.  Here, look and tell me what that is on the little rise.  I’m afraid our worst fears are going to come true.”

“Well, you’re right, Andy,” replied the other, after he had clapped the binoculars to his eyes.  “That’s a cannon, all the same, and they’re getting ready to shoot!”

“Oh! my!  It makes a fellow’s flesh just creep, to think of being banged away at with a great big cannon!” declared Andy.

“This one isn’t so very big, I think.  And now we’re nearly opposite where the fire burns.  They’re going to make a move to show their hand.  Drop down flat on the deck, Andy—­quick with you!” and Frank, as he spoke, set the example himself.

Hardly had the two boys thus thrown themselves down than there was a heavy boom, accompanied by a brilliant flash of fire from the shore.

The revolutionists had fired upon the little steam yacht!

CHAPTER XII.

A GREAT SURPRISE.

“Wow! now, what do you think of that?” exclaimed Andy, raising his head, just as one of the big turtles native to these warm waters might thrust his out of his shell.

“Why, that was only a warning to bring us up short, and pay attention!” declared Frank.  “Because, as you saw, the ball splashed the water ahead of our bow.”