The Thames
Paris, the junction of the various waterways, becomes the capital of a new state, and the influence of its kings leads out upon every side along the river valleys which fall into the main valley of the Seine.
There are but two considerable modifications to the use for habitation of slow and constant rivers: their value is lessened or interrupted by precipitous banks or they are rendered unapproachable by marshes. The first of these causes, for instance, has singularly cut off one from the other the groups of population residing upon the upper and the lower Meuse, as it has also, to quote another example, cut off even in language the upper from the lower Elbe.
From this first species of interruption the Thames is, of course, singularly free. There is no river in England, with the exception of the Trent, whose banks interfere so little with the settlement of men in any place on account of their steepness.
As to the second, the Thames presents a somewhat rare character.
The upper part of the river, which is in lowland valleys the most easily inhabited, and the part in which, once the river is navigable, will be found the largest number of small settlements, is in the case of the Thames the most marshy. From its source to beyond Cricklade the river runs entirely over clay; thenceforward the valley is a flat mass of alluvium,
