distance of the walking cat. Once he made a complete circuit, but always
carefully out of reach; and in the end he returned to his master's legs
and rubbed vigorously against him. Flame did not like the performance at
all: that much was quite clear.

For several minutes John Silence watched the performance of the cat with
profound attention and without interfering. Then he called to the animal
by name.

"Smoke, you mysterious beastie, what in the world are you about?" he
said, in a coaxing tone.

The cat looked up at him for a moment, smiling in its ecstasy, blinking
its eyes, but too happy to pause. He spoke to it again. He called to it
several times, and each time it turned upon him its blazing eyes, drunk
with inner delight, opening and shutting its lips, its body large and
rigid with excitement. Yet it never for one instant paused in its short
journeys to and fro.

He noted exactly what it did: it walked, he saw, the same number of
paces each time, some six or seven steps, and then it turned sharply and
retraced them. By the pattern of the great roses in the carpet he
measured it. It kept to the same direction and the same line. It behaved
precisely as though it were rubbing against something solid.
Undoubtedly, there was something standing there on that strip of carpet,
something invisible to the doctor, something that alarmed the dog, yet
caused the cat unspeakable pleasure.

"Smokie!" he called again, "Smokie, you black mystery, what is it
excites you so?"