Ned left the tall, thin gentleman in the station building engaged in the study of the time-table. But he did not long remain there. As the dejected little lad, who had not realized how he had been upborne by his secret hope of help and counsel from his father's old friends till it was snatched from him, took his way along the darkening shadowy paths, the tall man was once more swiftly afoot, and although he passed Ned and walked openly in advance he was determined no more to lose trace of the boy. The idea of quitting the city, which the inquiry at the station had revealed, precipitated the necessity of prompt action. Very little more time could now be accorded to the line of investigation which the detective was pursuing,--the hope of discovering the boy in communication with the incendiaries. It would be necessary to arrest him forthwith, lest he escape from the town, and with him vanish the only clue as yet developed of the origin and perpetrators of the crime. Nevertheless the detective determined that he would still seek in this limited interval to secure some inkling, some vestige of a theory, that might lead to the unmasking of the principals in this nefarious affair. Thus he was acutely conscious of the patter of the small feet as they came nimbly along behind him; when at last they began to lag he turned from the road and sat down on a bench by the wayside, and there Ned noticed him for the first time since they had been in the park, and remembered when and where he had before seen him. Ned was relieved to observe as he passed that the man seemed to take no heed of him. He did not even look up. Perhaps in his turn Ned would not have again thought of the stranger, so frequently encountered, had he not turned back as he reached the big iron gate to gaze regretfully over the great green stretch of the park. The man was just rising from the bench under the tree; he stretched his limbs with much deliberation, caught up his cane and came slowly down the broad walk toward the gate. He too was about to leave the place. Ned could not have said why, but he determined that he would not ride back to town in the same car. He loitered. There were two of the cable double-cars waiting on the track. The foremost was nearly full of passengers,--the other altogether empty. "I'll take the car that he leaves," Ned said to himself. Impressed with the idea that he was watched, he had half expected that the man would hesitate and wait for him. To his surprise the stranger strode past without so much as a glance toward him and stepped upon the platform of the foremost car. "I'm the biggest fool in town!" thought Ned in scorn for his terrors, turning nevertheless toward the other car. "Go on!" said the grip-man of the empty cable car. "This car is going to turn in."