"Hold on there!" cried the young inventor, but, naturally, the fleeing one did not stop. Tom began to sprint, and as it was slightly down hill, he made good time. The figure ahead of him was running well, too, but Tom who could see better, now that he was out from under the trees, noticed that he was gaining. The fleeing one came to a little brook, and hesitated a moment before leaping across. This enabled Tom to catch up, and he made a grab for the figure, just as the man or boy sprang across the little stream. Tom missed his grip, but he was not going to give up. He scarcely slackened his speed, but, with the momentum he had acquired in racing down the hill, he, too, leaped across the brook. As he landed on the other side he made another grab for the figure, a man, as Tom could now see, but he could make out no features, as the person's hat was pulled down over his face. "I've got you now!" cried Tom exultantly, reaching out his hand. His fingers clutched something, but the next instant the young inventor went sprawling. The other had put out his foot, and tripped him neatly and, Tom throwing out his hands to save himself in the fall that was inevitable, went splashing into the brook at full length. The unknown, pausing a moment to view what he had done, turned quickly and raced off in the darkness. CHAPTER XI CROSSED WIRES More surprised than hurt, and with a feeling of chagrin and anger at the trick which had been played on him, Tom managed to scramble out of the brook. The water was not deep, but he had splashed in with such force that he was wet all over. And, as he got up, the water dripping from his clothes, the lad was conscious of a pain in his head. He put up his hand, and found that contact with a stone had raised a large lump on his forehead. It was as big as a hen's egg. "Humph! I'll be a pretty sight to-morrow," murmured Tom. "I wonder who that fellow was, anyhow, and what he wanted? He tripped me neatly enough, whoever he was. I've a good notion to keep on after him." Then, as he realized what a start the fleeing one had, the young inventor knew that it would be fruitless to renew the chase. Slowly he ascended the sloping bank, and started for home. As he did so he realized that he had, clasped in his fingers, something he had grabbed from the person he was pursuing just before his unlucky tumble. "It's part of his watch chain!" exclaimed Tom, as he felt of the article. "I must have ripped it loose when I fell. Wonder what it is? Evidently some sort of a charm. Maybe it will be a clue." He tried to discern of what style it was, but in the dark woods this was impossible. Then the lad tried to strike a match, but those in his pocket had become wet from his unexpected bath. "I'll have to wait until I get home," he went on, and he hastened his steps, for he was anxious to see what he had torn loose from the person who appeared to be spying on him.