THE CHARTOGRAPHERS OF THE STATION 195 



like other creatures, however, the sheep has to compromise with his 

 ideal; economy of physical labour forbids too long a daily climb to 

 camp, too great a daily descent to graze. The primitive instinct, there- 

 fore, that safety can only be attained on the highest possible top, becomes 

 modified by custom. In practice, at any rate, the sheep does not always 

 sleep on the summits or crowns of hills. On extensive stretches where 

 there are no available natural camping sites, where hill-tops are distant, 

 or where cliff formation makes their attainment difficult, camps are formed 

 on the slopes. It is in such localities that sleeping-shelves have grown 

 out from the hillsides, like the lip ornaments of the women of certain 

 African tribes, or as fungus projects from dead timber. They are built 

 with the same enormous patience as a.re the viaducts decades going 

 towards the construction of a perfect ledge. Each of them represents 

 the labour of generations of sheep the thousandfold repetition of a 

 natural habit. Before a sheep lies down, his custom is to turn round 

 twice or thrice like a dog. He then rests with his feet beneath his 

 body. On an even slope, such as we have imagined, his slipping 

 downhill is only prevented by the resistance of hoof and knee. His 

 weight presses the turf upon which he lies downwards in an immeasur- 

 ably minute degree, and inwards also to an extent almost equally in- 

 tangible. For long these two opposite pressures, inward and downward, 

 are the only factors that count. Later, however, the mere bulge in the 

 hillside becomes the incipient shelf. Its projection begins to arrest the 

 almost infinitesimal amount of water-borne silt that percolates through 

 the grass-blades during wet weather. As the sheep, turning and scrap- 

 ing, settles himself for the night, in dry weather a small quantity of dust 

 is likewise shuffled towards the outer edge of the shelf. At a more 

 advanced stage a sheep does not always rise to relieve himself his 

 droppings begin, instead of rolling down the slope, to rest on the lip 

 of the now rapidly -growing ledge. In summer they blend with the 

 dust of his nightly circlings and preliminaries of rest. With slight 

 rains and dews they are trodden into a compost that nourishes the 

 grass-roots. The sleeping -ledge in time becomes perfect, thrusting 

 itself out at right angles to the slope, like a swallow's nest gummed 

 to a wall. The tendency of the most highly-finished of these sleeping- 

 shelves is to become in their last stage very slightly concave, their 

 edges upheld chiefly by a mass of meadow-poa roots. They must 

 then, on a well-drained slope, be most dry and comfortable couches. 



