HYDROGRAPHY. The water parting is situated much nearer the west than the east coast, with the result that the larger number of rivers flow to the east; with the exception of the western Severn, the eastern rivers are the longest, and their basins larger than the western basins. As the eastern rivers of England flow sluggishly down the gentle slope of the plain lands, it is nat-. ural that they should be least liable to floods and most important for navigation. Their value for commerce is somewhat impaired, however, by the fact that, crossing the softer rocks of the plain, they carry down a great deal of alluvium with which their mouths are often seriously clogged. The Tyne, Wear, and Tees of Northeast England have a course of only 70 or 80 miles, and their commercial importance depends upon the great coal-fields (Tyne and Wear) and the iron and salt deposits (Tees) near them. The basin of the Humber embraces 10,000 square miles, from the mineral beds of the Pennine slopes through the rich agricultural plains; the Aire, Ouse, Trent, and other tributaries help to make it one of the most useful river systems in Eng land. The Thames rises only 300 feet above the sea, but it has a long course of about 200 miles. Its sluggish current, its well-protected estuary, and the tides which carry the largest ocean vessels 50 miles up to London Bridge, help to make the Thames one of the largest commerce-carriers among the world's rivers. The important western rivers of South Britain are limited to the Severn and the Mersey. The Severn is the longest Brit ish river (nearly 250 miles), with tides of ex traordinary height, and empties through one of the largest and richest coal-fields in Europe. It is
navigable for a long distance, and is a great com merce-carrier. The Mersey is a short river, rising on the Pennine slopes and obstructed at its mouth by a shifting bar, but its proximity to a rich coal-field and to the great manufacturing dis trict of England gives it immense importance in commerce. The western rivers of Scotland, ex cepting the Clyde, are only short, torrential, and commercially valueless streams; but the Clyde, artificially widened and deepened in its lower part at enormous expense, is the most important river in Scotland, and all the industries of the Low lands a-nd Southern Uplands—agricultural, min eral, and manufacturing—are represented in its trade. With this exception, the longer and more gently flowing eastern rivers are most useful. The Tay, Spey, and Tweed are all about 100 miles, and the Dee and the Don about SO miles long. The Tay and the Forth are great water highways, commanding all the river traffic pass ing through the eastern-central portion of Scot land. The two famous lake regions of Great Britain are in the Highlands of Scotland, where here and there in the valleys the rivers have spread out into long and narrow lakes or lochs, which follow the curves of the hillsides and con tribute much to the beauty and charm of this picturesque region, and the Lake District of the Cumbrian Mountains in Northwest England, al ready mentioned.