and has therefore created a point of high strategical importance in the fortified hill of Lewes. But, unlike the Adur, the maritime portion of its course is of some length, and during these eight miles or so between Lewes and the mouth at Newhaven it rather resembles the lower part of the Arun. It has the same treeless, marshy sides, highly embanked for the formation of water meadows, the same strong, scouring tide, the same violent current, but, luckily for the London, Brighton, and South Coast Railway, not the same bar. The entry at Newhaven is particularly easy, the best in the county, and would be fairly easy even without the dredging that is carried on, or the breakwater that defends it from the south-west. These three rivers between them form the main hydrographical features of the centre of the county; their three harbours standing at almost exactly regular intervals are the sole entries to the west and middle of Sussex; the three gaps in the Downs behind those harbours are the three gates to South England from the sea; the three castles that defend those gaps complete the significance of the series. The Cuckmere is but a very small stream coming out just beyond Newhaven with Seaford at its mouth, and would be scarcely worth mentioning were it not for the fact that, like its larger sisters, it shows that singular capacity for cutting right down through the chalk hills and making a gap through which it can pass to the sea. This feature, which is common to the Sussex rivers, is also discovered in the streams which cross the northern chalk range into the Thames valley. These also are three in number--the Wey, the Mole, and the Darent. And it is conjectured by scientists that these three rivers, like those other three in Sussex, the Arun, the Adur, and the Ouse, run independent of the chalk hills, and cut through them from the following cause: the Wealden heights, the forest ridge that is, in which all six take their rise, is conceived to be geologically much older than the North or the South Downs, and it is presumed that the rivers had already formed their valleys, and were already beginning to erode the surface of the land before the chalk hills began to arise, so that as the Downs gradually rose the little rivers continued their sawing, and kept to their original level while the great heaps of white shell which were building up our hills rose upon either side of their valleys. This theory, unfortunately, like most scientific theories, and especially geological ones, is traversed by another theory equally [Illustration: THE ROTHER AT FITTLEWORTH] [Sidenote: THE EASTERN ROTHER]