As the night wore on the silence grew deeper and deeper, and only at rare intervals he heard the sound of wheels on the main road a hundred yards away, where the horses went at a walking pace owing to the density of the fog.  The echo of pedestrian footsteps no longer reached him, the clamour of occasional voices no longer came down the side street.  The night, muffled by fog, shrouded by veils of ultimate mystery, hung about the haunted villa like a doom.  Nothing in the house stirred.  Stillness, in a thick blanket, lay over the upper storeys.  Only the mist in the room grew more dense, he thought, and the damp cold more penetrating.  Certainly, from time to time, he shivered.

The collie, now deep in slumber, moved occasionally,—­grunted, sighed, or twitched his legs in dreams.  Smoke lay on his knees, a pool of warm, black fur, only the closest observation detecting the movement of his sleek sides.  It was difficult to distinguish exactly where his head and body joined in that circle of glistening hair; only a black satin nose and a tiny tip of pink tongue betrayed the secret.

Dr. Silence watched him, and felt comfortable.  The collie’s breathing was soothing.  The fire was well built, and would burn for another two hours without attention.  He was not conscious of the least nervousness.  He particularly wished to remain in his ordinary and normal state of mind, and to force nothing.  If sleep came naturally, he would let it come—­and even welcome it.  The coldness of the room, when the fire died down later, would be sure to wake him again; and it would then be time enough to carry these sleeping barometers up to bed.  From various psychic premonitions he knew quite well that the night would not pass without adventure; but he did not wish to force its arrival; and he wished to remain normal, and let the animals remain normal, so that, when it came, it would be unattended by excitement or by any straining of the attention.  Many experiments had made him wise.  And, for the rest, he had no fear.

Accordingly, after a time, he did fall asleep as he had expected, and the last thing he remembered, before oblivion slipped up over his eyes like soft wool, was the picture of Flame stretching all four legs at once, and sighing noisily as he sought a more comfortable position for his paws and muzzle upon the mat.

* * * * *

It was a good deal later when he became aware that a weight lay upon his chest, and that something was pencilling over his face and mouth.  A soft touch on the cheek woke him.  Something was patting him.

He sat up with a jerk, and found himself staring straight into a pair of brilliant eyes, half green, half black.  Smoke’s face lay level with his own; and the cat had climbed up with its front paws upon his chest.