"All right, then. Come on," and Adrian led the way into the car ahead, while Donald and Pedro stood by to uncouple as soon as they passed the clump of trees before alluded to. Almost at the same instant several sharp blasts from the whistle gave the danger signal, and Donald threw over the coupling lever and put on the brake. The coaches slowed quickly down, but the engine and express car dashed in between the horsemen stationed on either side of the track. Prepared for what they knew was coming, the engineer and fireman had thrown themselves down on the floor of the cab, while Adrian, Billie and the three guards poured a volley into the robbers as they passed and several horses lost their mounts. This fire was followed by a fusillade from the horsemen and a minute later the engine, striking an unspiked rail, rolled completely over into the ditch, wrenching itself clear from the express car, which, after bumping over the ties for several seconds, suddenly ceased its antics and glided smoothly along. As by a miracle it had run completely over the space from which the rail had been loosed and landed upon the good track, down which it now sped. So unexpected was the change from ties to track that Adrian and Billie were unable for a few moments to understand what had happened. Then Billie rushed to the door and seized the hand brake. "Grab hold and help stop this car," he yelled to Adrian, "or there is no knowing where we'll land." Adrian hastened to obey, but the wrench that had been given the car when the engine broke loose had put the brake out of commission and the car sped on. The three Mexican guards now appeared on the platform and gazed wildly up the track where they could see the fight going on between the bandits and their companions. "What shall we do, Senor?" asked one of them. "Search me," from Billie. "How long is this grade?" "It is down hill all the way to Pitahaya." "How far is that?" "Ten kilometers from Pachuca." "That must be about three miles farther," said Adrian. "Correct," from Billie, "but unless it's a mighty steep up-grade the other side of Pita-what's-its-name, we're going so fast we'll not stop till we've run away past it." "Well, what of it? We can coast back, can't we?" The car gave a lurch to one side that almost threw the boys off the platform. "We're certainly going some," called Adrian. "Hang on!" And hang on they did until they dashed past the little station of Pitahaya and after several minutes began to slow down. "This is a little better," Adrian finally remarked as the car showed some sign of coming to a stop. "Yes, indeed," from Billie. "I suppose we'll come to a dead stop soon. Do you think she'll start back on her own hook, or shall we have to start her?" "We'll soon see," and see they did, for a couple of minutes later the car came to a stop.