He had managed to let the Serbian boy know what they meant to do about getting his sister and himself on his native soil. How those black eyes snapped as the plan was unfolded to him! Jack fancied he could see unshed tears there also, showing how their generosity must have affected the other. He could not express his gratitude by repeating that one word “thank” again, but he did display it by almost fiercely seizing Jack’s hand and actually kissing it, an act that made the American boy feel exceedingly queer, because he was not accustomed to such things.

They kept, as a rule, closer to the right bank of the river, for that would in time prove to be the one on which the Serbian capital was located. Besides, Jack believed it would answer their purposes better in case circumstances forced them to make a hurried landing, so that their passengers might conceal themselves in the brush.

The sun was hot again, and as the afternoon began to wear along they found that the breeze created by their own swift passage was the only invigorating thing to be met with.

“But it’s beginning to cloud up, you can see,” Josh remarked, when Buster complained that he was melting away with the heat; “and once the old sun gets out of sight it’ll be a whole lot more comfy.”

“I’ve been watching those clouds,” remarked Jack, “and they please me a whole lot, because we must have a cloudy night if we’re ever going to run past the batteries on both sides of the river.”

“Whew! that sounds as if we might be away back in the civil war, trying to pass Memphis on a gunboat, with the Confeds whanging away at us to beat the band. But, of course, you don’t expect to have any real trouble getting by, do you, Jack?”

“So far as I can see, there’s no reason why we should meet up with any,” the skipper informed him.

“And once we’re well by Belgrade the worst will be over,” cheerily observed Josh. “You see, the railroad runs down through Serbia from the capital, and any invasion must, of course, follow the Morava River, because Serbia is a mountainous country, and there are passes through which troops have to go if ever they hope to reach Nisch down near the middle of the nation.”

“Seems like you’ve been reading up on Serbia, Josh,” ventured George.