Slight of body, but vigorous and wiry, and as full of scientific enthusiasm as when he was thirty years younger, he tramped the hills, taking long walks and climbs alone, or shorter ones with Hoyle at his heels like a devoted dog, shrilling questions as he ran to keep up. These the good doctor answered according to his own code, or passed over as beyond possibility of reply with quizzical counter-questioning.

They sat together one day, eating their luncheon in the shelter of a great wall of rock, and below them lay a pool of clear water which trickled from a spring higher up. Now and then a bullfrog would sound his deep bass note, and all the time the high piping of the peepers made shrill accompaniment to their voices as they conversed.

The doctor had made an aquarium for Hoyle, using a