The boys got out to stretch their legs. The warm, sweet, balmy air was a new and novel thing to them. They strolled up and down the gravel walk, watching the natives. Hal said he rather liked the looks of their brown bare feet and the thin cotton trousers and shirts, but he fancied the enormous sombreros were too heavy and unwieldy. Ken spoke to several pleasant-faced Mexicans, each of whom replied: “No sabe, Señor.” The ticket agent at the station was an American, and from the way he smiled and spoke Ken knew he was more than glad to see one of his own kind. So, after Ken had replied to many questions about the States, he began to ask some of his own. “What’s the name of the waterfall we passed?” “Micas Falls,” replied the agent. “And the river?” “It’s called the Santa Rosa.” “Where does it go?” The agent did not know, except that it disappeared in the jungle. Southward the country was wild. The villages were few and all along the railroad; and at Valles the river swung away to the southwest. “But it must flow into the Panuco River,” said Ken. He had studied maps of Mexico and had learned all that it was possible to learn before he undertook the journey. “Why, yes, it must find the Panuco somewhere down over the mountain,” answered the agent. “Then there are rapids in this little river?” asked Ken, in growing interest. “Well, I guess. It’s all rapids.” “How far to Tampico by rail?” went on Ken. “Something over a hundred miles.” “Any game in the jungle hereabouts--or along the Santa Rosa?” continued Ken. The man laughed, and laughed in such a way that Ken did not need his assertion that it was not safe to go into the jungle. Whereupon Ken Ward became so thoughtful that he did not hear the talk that followed between the agent and Hal. The engine bell roused him into action, and with Hal he hurried back to their seats. And then the train sped on. But the beauty of Micas Falls and the wildness of the Santa Rosa remained with Ken. Where did that river go? How many waterfalls and rapids did it have? What teeming life must be along its rich banks! It haunted Ken. He wanted to learn the mystery of the jungle. There was the same longing which had gotten him into the wild adventures in Penetier Forest and the Grand Cañon country of Arizona. And all at once flashed over him the thought that here was the jungle river for him to explore. “Why, that’s the very thing,” he said, thinking aloud. “What’s wrong with you,” asked Hal, “talking to yourself that way?” Ken did not explain. The train clattered between green walls of jungle, and occasionally stopped at a station. But the thought of the jungle haunted him until the train arrived at Tampico. Ken had the name of an American hotel, and that was all he knew about Tampico. The station was crowded with natives. Man after man accosted the boys, jabbering excitedly in Mexican. Some of these showed brass badges bearing a number and the word _Cargodore_.