Page:The Canal System of England.djvu/16

 a cradle could be hauled, were in use, but this contrivance in its primitive form was very inadequate, and could only be employed to a limited extent.

The lock, as now used, was not invented until the 14th century. By its introduction the construction of canals for inland navigation received a fresh impetus, and it is, in fact, only at this time that the history of modern canals may be said to have commenced.

The recognised need in these early times was that river-navigation should be rendered more efficient, and thus we find that the improvement of the navigation of the Thames was undertaken in 1423, that of the Lea in 1425, the Ouse in 1462, the Severn in 1603, the Stour in 1504, the Humber in 1631, and the Welland in 1571.

In 1572 the first Ship Canal was constructed in England—the "Exeter"—a comparatively short waterway which had received Royal Assent in 1539. From this date canal schemes were entered upon more extensively.

During the 17th century many canalisation schemes were undertaken, thus between the years 1623 and 1699, the Rivers Colne, Itchin, Wye, Avon, Medway, Wey, Bure, Witham, Fal and Vale, Aire and Calder, and Trent were all more or less canalised.

In the next century similar projects for river and canal navigation proceeded apace. The following examples