A hundred and fifty yards behind them down the centre of the empty road the first of their pursuers came pounding and panting—­a fat but powerful policeman who had distanced all the rest.  He came on at a splendid pace for so portly a figure; but, like all heavy bodies in motion, he gave the impression that it would be easier for him to increase his pace than to slacken it suddenly.  Nothing short of a brick wall could have abruptly brought him up.  Turnbull turned his head slightly and found breath to say something to MacIan.  MacIan nodded.

Pursuer and pursued were fixed in their distance as they fled, for some quarter of a mile, when they came to a place where two or three of the trees grew twistedly together, making a special obscurity.  Past this place the pursuing policeman went thundering without thought or hesitation.  But he was pursuing his shadow or the wind; for Turnbull had put one foot in a crack of the tree and gone up it as quickly and softly as a cat.  Somewhat more laboriously but in equal silence the long legs of the Highlander had followed; and crouching in crucial silence in the cloud of leaves, they saw the whole posse of their pursuers go by and die into the dust and mists of the distance.

The white vapour lay, as it often does, in lean and palpable layers; and even the head of the tree was above it in the half-daylight, like a green ship swinging on a sea of foam.  But higher yet behind them, and readier to catch the first coming of the sun, ran the rampart of the top of the wall, which in their excitement of escape looked at once indispensable and unattainable, like the wall of heaven.  Here, however, it was MacIan’s turn to have the advantage; for, though less light-limbed and feline, he was longer and stronger in the arms.  In two seconds he had tugged up his chin over the wall like a horizontal bar; the next he sat astride of it, like a horse of stone.  With his assistance Turnbull vaulted to the same perch, and the two began cautiously to shift along the wall in the direction by which they had come, doubling on their tracks to throw off the last pursuit.  MacIan could not rid himself of the fancy of bestriding a steed; the long, grey coping of the wall shot out in front of him, like the long, grey neck of some nightmare Rosinante.  He had the quaint thought that he and Turnbull were two knights on one steed on the old shield of the Templars.

The nightmare of the stone horse was increased by the white fog, which seemed thicker inside the wall than outside.  They could make nothing of the enclosure upon which they were partial trespassers, except that the green and crooked branches of a big apple-tree came crawling at them out of the mist, like the tentacles of some green cuttlefish.  Anything would serve, however, that was likely to confuse their trail, so they both decided without need of words to use this tree also as a ladder—­a ladder of descent.  When they dropped from the lowest branch to the ground their stockinged feet felt hard gravel beneath them.