Having heard the horn, Mr. Billers expected an automobile would pass. But when no car flashed by he turned indolently in his seat and looked behind. The roadway was clear. There was not an automobile in sight. He did not see Chet, doubling up with laughter, on the back of the wagon. He gazed doubtfully at the Hardy boys, who were standing at the curb, trying to conceal their smiles.

“Could ’a’ swore I heard a horn,” grunted Mr. Billers. Then he tugged at the lines and brought the horses into the middle of the road again.

Instantly the horn shrieked again. This time it was even louder and more insistent than before. It seemed that an automobile was right behind the wagon, clamoring to pass.

Almost automatically, Mr. Billers yanked at the reins and the horses again went to the side of the road.