At last Ward Porton gained a point where one of the foundations of the bridge rested on comparatively solid ground, with the river behind and a wide stretch of marshland ahead. Here there was a long ladder used by the workmen, and down this the rascal went as fast as his feet could carry him. By the time Dave reached the top of the ladder, Porton was well on his way over the solid ground. Soon the gathering darkness hid him from view. Knowing that it would be next to useless to attempt to follow the rascal now that he had left the vicinity of the bridge, Dave returned to where he had left Roger. Then the pair started slowly back to the end of the bridge from which they had come. "I can't understand what brought Ward Porton here," remarked Roger, when the chums had once more gained the swimming-place. "Do you suppose he knew you were in this vicinity, Dave?" "Possibly, Roger. But at the same time, I don't think that would explain his presence here. He wouldn't dare to impersonate me around this camp. He'd be sure to be caught at it sooner or later." "Well, I don't understand it at all." "Neither do I. I am sorry that we didn't catch the rascal," returned Dave, soberly. When they went back into camp they informed Frank Andrews, and also Mr. Obray, of what had occurred. These men had already heard some of the particulars regarding Dave's double and the disappearance of the Basswood fortune. "Too bad you didn't get him," said Frank Andrews. "But you be careful how you run over that unfinished bridge, unless you want to have a nasty fall and either get killed or else crippled for life." Several days went by, including Sunday, and nothing more was seen or heard of Ward Porton although the lads made a thorough search for him. Dave sent letters home and to Ben Basswood, telling the folks in Crumville of what had happened. "A little greaser to see you, Dave," remarked one of the civil engineers as Dave was coming from an unusually difficult afternoon's work. He walked to where his fellow worker had pointed, and there saw a dirty, unkempt Mexican lad standing with a letter in his hand. The communication was addressed to Dave, and, opening it, he read the following: "I have broken with Tim Crapsey and have the Basswood miniatures here with me safely in Mexico. If the Basswoods will pay me ten thousand dollars in cash they can have the pictures back. Otherwise I am going to destroy them. I will give them two weeks in which to make good. "As you are so close at hand, maybe you can transact the business for Mr. Basswood. When you are ready to open negotiations, send a letter to the Bilassa camp, across the border, and I will get it. "WARD PORTON." CHAPTER XXVII ACROSS THE RIO GRANDE Dave read the note from Ward Porton with intense interest, and then passed it over to Roger. "What do you know about that!" exclaimed the senator's son, after he had perused the communication. "Do you think Porton tells the truth?"