canals or partially destroyed by the development of railways. Thus it is certain that so small a stream as the Adur in Sussex floated barges up to the boundaries of Shipley Parish; that the Stour was habitually used beyond Canterbury; that so tiny a tributary as the Ant in Norfolk was followed up from its parent Bure to the neighbourhood of Worsted.
In this connection the Thames is of an especial interest, for it had, in proportion to its length, the greatest section of navigable non-tidal water of any of the shorter rivers in Europe. Until the digging of the Thames and Severn Canal at the end of last century it was possible, and even common, for boats to reach Cricklade, or at anyrate the mouth of the Churn. And even now, in spite of the pumping that is necessary at Thames head and the consequent diminution of the volume of water in the upper reaches, the Thames, were water carriage to come again into general use, would be a busy commercial stream as high up as Lechlade.
This exceptional sector of non-tidal navigable water cutting right across England from east to west, and that in what used to be the most productive and is still the most fertile portion of the island, is the chief factor in the historic importance of the Thames.
From Cricklade to the navigable waters of the Severn Valley is but a long day's walk; and one may say that even in the earliest times there was thus provided a great highway