Out onto the road rolled the automobile. During the little daylight that had remained after his arrival at home and following the discovery of the loss of the tank Tom and Ned had traced it, by the marks of the big steel caterpillar belts, to the main road. It had gone along that some distance, just how far could not be said. "But by using the searchlight of the auto we can trace her as long as they keep her on the road," said Tom. "After that we'll have to trust to luck, and to what inquiries we can make." The touring car carried a powerful lamp, and by its gleams it was easy to trace for a time the progress of the ponderous tank. There was no need to make inquiries of persons living along the way, though once or twice Tom did get out to ask, confirming the fact that the big machine had rumbled past in a direction away from the Swift home. "I had an idea they might have doubled on their tracks for a time, and backed her up just to fool us," Tom said. "They might do that, keeping her in the same tracks." But this, evidently, had not been done, and the tank was making good speed away from the Swift house. They kept up the search until about midnight, and then a heavy rain began just before they reached a point where several roads branched. "Luck's with them!" exclaimed Tom. "This will wash away the marks, and we'll have to go it blind. Might as well put up here for the night," he added, as they came to a village hotel. It was evident that little more could be done in the rain and darkness, and there was danger of over-running the trail of the tank if they kept on. So they turned in at the hotel and got what little rest they could in their anxious state of minds. Tom tried to be cheerful and to look for the best, but it was hard work. The tank was his pet invention, and, moreover, that her secrets should fall into the hands of the enemy and be used for Germany and against the United States eventually, made the young inventor feel that everything was going wrong. The rain kept up all night, and this would make it correspondingly hard for them to pick up the trail in the morning. "The only thing we can do is to make inquiries," decided Tom. "Fortunately, the tank can't easily be hidden." They started off after an early breakfast. The roads were so muddy and wet that traveling was difficult and dangerous for the automobile, and they were disappointed in finding no one who had seen or heard the tank pass up to a point not far from the hotel where they had stayed overnight. From then on the big machine seemed to have disappeared. "I know what they've done," Tom said, when noon came and they had found no trace of the ponderous war machine. "They've left the road and taken her cross country, and we can't find the spot where they did this because the rain has washed out the marks. Well, there's only one thing left to do." "What's that?" asked Ned.