The lamp had burned low and the fire was nearly out, yet Dr. Silence saw in a moment that the cat was in an excited state.  It kneaded with its front paws into his chest, shifting from one to the other.  He felt them prodding against him.  It lifted a leg very carefully and patted his cheek gingerly.  Its fur, he saw, was standing ridgewise upon its back; the ears were flattened back somewhat; the tail was switching sharply.  The cat, of course, had wakened him with a purpose, and the instant he realised this, he set it upon the arm of the chair and sprang up with a quick turn to face the empty room behind him.  By some curious instinct, his arms of their own accord assumed an attitude of defence in front of him, as though to ward off something that threatened his safety.  Yet nothing was visible.  Only shapes of fog hung about rather heavily in the air, moving slightly to and fro.

His mind was now fully alert, and the last vestiges of sleep gone.  He turned the lamp higher and peered about him.  Two things he became aware of at once:  one, that Smoke, while excited, was pleasurably excited; the other, that the collie was no longer visible upon the mat at his feet.  He had crept away to the corner of the wall farthest from the window, and lay watching the room with wide-open eyes, in which lurked plainly something of alarm.

Something in the dog’s behaviour instantly struck Dr. Silence as unusual, and, calling him by name, he moved across to pat him.  Flame got up, wagged his tail, and came over slowly to the rug, uttering a low sound that was half growl, half whine.  He was evidently perturbed about something, and his master was proceeding to administer comfort when his attention was suddenly drawn to the antics of his other four-footed companion, the cat.

And what he saw filled him with something like amazement.

Smoke had jumped down from the back of the arm-chair and now occupied the middle of the carpet, where, with tail erect and legs stiff as ramrods, it was steadily pacing backwards and forwards in a narrow space, uttering, as it did so, those curious little guttural sounds of pleasure that only an animal of the feline species knows how to make expressive of supreme happiness.  Its stiffened legs and arched back made it appear larger than usual, and the black visage wore a smile of beatific joy.  Its eyes blazed magnificently; it was in an ecstasy.

At the end of every few paces it turned sharply and stalked back again along the same line, padding softly, and purring like a roll of little muffled drums.  It behaved precisely as though it were rubbing against the ankles of some one who remained invisible.  A thrill ran down the doctor’s spine as he stood and stared.  His experiment was growing interesting at last.