Then he noticed that Joe, too, was gazing thoughtfully down the railway tracks. Joe raised a sandwich to his lips absently, essayed a bite and missed the sandwich altogether. Still he continued gazing at the two water towers. Finally Joe turned and looked at his brother. In the eyes of both was the light of a great discovery. They knew that they were both thinking of the same thing. "Two water towers," said Frank slowly. "An old one and a new one." "And Jackley said--" "He hid the stuff in the old tower." "He was a railwayman." "Why not?" shouted Joe, springing to his feet. "Why couldn't it have been the old water tower? He used to work around here." "He didn't say the old tower of Tower Mansion, after all. He just said 'the old tower!'" "Frank, I believe we've stumbled on the clue!" "It would be the natural thing for him to come to his old haunts after the robbery. And if he found he couldn't get away with the stuff he would hide it somewhere he knew. The old water tower! Why didn't we think of it before, Joe? Why, that _must_ be the place!" CHAPTER XXII THE SEARCH Lunch, motorcycles--everything else was forgotten! With a wild yell of delight, Frank began to scurry down the embankment that flanked the right of way. At his heels ran Joe. They raced down the grassy slope until they came to the wire fence. They scrambled over it, heedless of tearing their clothes. They dashed up on to the cinder path beside the rails. "What if we're wrong, Frank?" panted Joe. "We can't be wrong. I just know that's what Jackley meant. The old tower. It was the old _water_ tower he meant all along. He didn't have time to explain." The Hardy boys were tingling with excitement. It seemed that they could never reach the water tower. They dashed along the cinder path with all the speed at their command, but the tower still seemed a long distance away. "If only we _have_ stumbled on the secret after all, Joe!" "It'll clear Mr. Robinson--" "We'll get the reward--" "Dad'll be proud of us." These thoughts gave them new strength and their hopes were high as they neared the tower. The structure reared gloomily from beside the tracks. At close quarters it was even more decrepit, even more in a state of disrepair than they had imagined. The old tower had been abandoned for some time in favor of the new tank nearer the station. It sagged perilously. The ladder that led to the top lacked so many rungs that at first the boys feared they would be unable to ascend. "If Jackley got up this ladder, we can do the same," said Frank, as he stopped, panting, at the bottom. "Let's go." He began to scramble up the flimsy ladder. Hardly had he ascended four rungs than there came an alarming crack! "Look out!"