It will be borne in mind that the canoe was moving toward the northern end of the lake, in which direction the two occupants faced. Before them was the section in which they hoped to find their missing friend. Their backs were turned upon the workshop of Professor Morgan in the neighborhood of the little town of Purvis. When last seen he was traveling in that direction, and the brothers ought not to have forgotten to watch the sky to the south. None the less they did so and the oversight proved unfortunate.
Harvey said something which Dick did not fully catch. Without ceasing to swing his paddle, he turned his head, glanced over his shoulder and asked for a repetition of the words. Before the younger could comply, Dick said in an excited undertone:
“Cover your face with your handkerchief, Harv!”
The younger was quickwitted enough to obey without stopping an instant to learn the reason for the strange command. He snatched out the piece of silk and held it to his nose in a natural manner and awaited the explanation which he knew would come in a second or two.
At the moment of looking back, Dick Hamilton saw the monoplane coming with the speed of a hurricane barely fifty feet aloft and directly over them. Professor Morgan had noticed the two young men in the canoe and a tinge of suspicion caused him to sail thus low that he might gain a look at the faces of the occupants. Since the elder brother was a stranger to him, it was better that his countenance should be clearly seen, but one glimpse of the face of Harvey would reveal everything. If he bowed his head to hide his features the act would be significant, but calling into play his handkerchief had nothing singular about it. To give naturalness to the action, Harvey emitted a blast from his nasal organ which suggested the honk of an automobile horn. In the uninterrupted stillness the aviator probably heard it.
Dick gazed aloft and watched the swoop of the machine with the strange man controlling the levers, who leaned forward and over, and scrutinized the couple so keenly that Dick caught the gleam of the piercing black eyes, and circled his dripping paddle about his shoulders by way of salutation; but the Professor made no acknowledgment. He continued to peer sharply downward until he had shot well past, when he curved upward and continued his swift course over the sheet of water and the wooded country beyond. It could not be seen that he glanced again behind him but skimmed away with undiminished swiftness.
CHAPTER XIII.
DISCOVERY IMPENDS.
HARVEY asked in a muffled voice: “May I take away my handkerchief?”