“My mistake,” said the penitent Tuckerman. “I see that it won’t do for me to think of two things at once when I’m out on this lily-pad.”

“Paddle—quickly now,” Ben ordered. “But not too quickly. There’s a rip off that ledge.”

They passed the rip and came into smoother water. Presently they were on the ocean side of the island. “There’s the creek where we saw the footprints,” said Ben.

“Don’t point out anything else to me,” said Tuckerman. “If I move my left leg I can’t get it back in place.”

By the time they reached the southern end of the island the bow-paddler felt as if the muscles of his knees were tied in hard knots. “Do you mind,” he said in a tone of apology, “if I stop paddling for a couple of minutes and unwind myself? I’ll move very slowly.”

“Go ahead,” said Ben. “I’ll balance the canoe.”

Tuckerman pushed himself back, then very carefully unwound his long legs, stretched them out with an exclamation of relief, rubbed the muscles, and then readjusted himself in a new and more comfortable position. “I suppose to be a really proficient canoeist,” he observed, “one ought to be made of rubber. There—how’s that? Didn’t I do it cleverly?”

“Wonderful!” said Ben.

Tuckerman picked up his paddle again, and, proud of his ability to move without rocking the boat, stuck the paddle in the water and gave a mighty sweep. The bow swung around, rocked, tilted; Tuckerman pressed his arm hard on the left-hand gunwale.

“Hold on, Professor!” cried Ben. “We don’t want to head out into the ocean. Keep your paddle out of the water. Steady there!” With alternate strokes to right and left Ben soon had the canoe back on its course parallel to the shore.