They combine the clearness of a mountain stream with only a degree more current than the slow-running rivers of central or eastern England. They savour, in short, of the unexpected. There is no stir nor movement of water on the hillsides, as in Wales or Devonshire, to suggest the natural corollary of a clear torrent in the valley below. The hills here, though graceful and delightful in their peculiar way, are more waterless than any clay ridge in Northamptonshire or Suffolk, for reasons already given. Nor does the chalk stream usually run like a western river. It moves at most times but little faster than the rivers on which men go boating or float-fishing for roach. Its environment is smooth, its course is peaceful, and its fall gradual. It is all this that gives the flavour and charm of the unexpected, when you arrive at the bank and find a stream gliding past your feet as translucent as if it had just gushed out from a limestone mountain in Cumberland. The Chalk Stream gives best evidence of its quality in being the natural home of the trout and grayling, fish that do not often flourish in, and are never indigenous to, slow-running streams of other than chalk origin. There are two Avons in Wiltshire which illustrate the contrast to perfection: the one which runs westward through the fat pastoral regions, the clays and greensands of north-west Wilts towards Bath and Bristol; the other, which rises in the Marlborough Downs, and cuts through the heart of Salisbury Plain, as translucent as a mountain stream. The last alive with lusty trout; the other, which moves slowly with murkier current over a muddier bottom, breeding only coarser fish and belonging to another family of rivers. The Kennet is assuredly of noble birth; for it is the offspring of the once sacred upland pastures of Avebury, where stand the uncanny fragments of the great prehistoric temple of the sun, and twines its infant arms around the mighty and mysterious mound of Silbury: the child, in fact, of one of the [Illustration: THE AVON, NEAR SALISBURY] [Illustration] three great wonders of Britain, leaving Stonehenge to its rival the southern Avon.