With the exception of the Thames—which it rivals, and with which for a number of years past it has run a neck-to-neck race—the Mersey is, so far as its volume of business is concerned, the most important river in the world. This, however, is an attainment of comparative modern origin. The first wet dock was constructed at Liverpool, in 1708-9, on the site now occupied by the Custom House. In the latter part of the same century several other docks were constructed. The dock estate has now an area of 1078 acres, the whole of which is appropriated to basins, docks, quays, and premises worked in connection therewith. THE WEAVER. The history of the navigation of the river Weaver, which adjoins the Mersey in Cheshire, supplies a notable example of what may be made of an originally insignificant and tortuous stream in order to adapt it for the requirements of commerce. The river has been canalised between Northwich and Chester, twenty miles of the navigation being artificial navigation, and the other thirty miles being river proper. In 1721 three Cheshire gentlemen obtained the first Act of Parliament for making the river Weaver navigable. The depth then provided for was only 4 feet 6 inches, and boats of more than 40 to 50 tons could not enter. About the year 1760, the navigation was carried down so as to enable vessels to enter at nearly all tides, and in 1810 the river was further improved by the Weston Canal, which is four miles long, enabling vessels of much deeper draught to enter without navigating a dangerous part of the old river. This canal forms a junction with the Bridgwater Docks at Weston Point, and a dock was formed in connection with it so as to enable vessels to wait for the tide. In 1830 the depth was increased to 7 feet 6 inches, with locks 88 feet long and 18 feet wide, capable of taking cargoes of 100 to 150 tons. There were at this time eleven single locks on the river, not including the entrances to the Mersey. About 1860, a second set of locks, having 10 feet of water on the sills, and 100 feet long by 22 feet wide, was placed by the side of the existing locks, and the number was reduced to nine pairs. The larger size, owing to the vessels being built almost to the shape of the lock, were capable of passing vessels with nearly 320 tons on board.