“It was a shame!” he confessed. “The poor old chap reined in his horses and made me come up and sit on the seat beside him. He asked me if I had walked very far and then he told me all about his argument with the policeman and the chauffeur. I could hardly keep my face straight.”

When the boys reached the lane that led in toward Willow Grove from the main road they broke into a run and raced into the woods, shouting and yelling like wild Indians. Once in the friendly shade of the trees they capered about in the joy of their Saturday freedom. Chet took charge of the lunches and stored them in a convenient clearing, and then began the rush for the river.

The day passed in the usual fashion of such days. They swam, they ate, they loafed about under the trees, they played games at imminent risk of life and limb, they explored the woods, and otherwise enjoyed themselves with all the happy energy of healthy lads. Joe Hardy, who was an amateur naturalist in his way, went roaming off by himself during the afternoon while the other boys were enjoying their third swim of the day, and penetrated deeper into the woods.

He poked about in the undergrowth, examining various flowers and plants that came to his attention, but discovered no specimens that he had not seen before. He was just on the point of going back to the other lads when he saw before him a small clearing. It was a part of the grove in which he had never been, so he ploughed on through the bushes until he found himself in a clearing that appeared to be part of an abandoned roadway.

It was in a low-lying part of the grove and the ground was wet. At one point it was muddy, and in this mud Joe saw something that aroused his curiosity.

“Tire tracks, eh! There’s been an automobile in here,” he muttered to himself. “I wonder how on earth a car could get this far into the woods!”

Then he remembered his father’s remarks on the value of developing his powers of observation, so he went over closer and examined the marks in the mud.

“That’s a strange tread,” he thought. “I’ve never seen a tire mark quite like that before.”

He gazed at it until he was sure that if he ever saw a similar auto tread again he would recognize it.

“That just goes to prove that Dad was right,” said Joe. “Probably I’ve seen auto tires like that often, but I’ve never noticed the markings, and now that I do notice one in particular it seems strange to me. But I wonder what an automobile was doing in here and how it came to get here in the first place!”

However, he gave the matter little further thought and retraced his steps through the woods until he returned to the other boys, who were getting dressed after their swim.

“I thought automobiles weren’t allowed in Willow Grove,” he said casually to Chet Morton.

“Neither they are. You have to park just inside the fence.”

“Well, somebody brought a car right down into the grove.”