Sanctioned by Parliament in 1769, six years before the Grand Trunk Canal was opened, the Leeds and Liverpool Canal was mainly designed to overcome the natural barrier, in the form of a chain of lofty hills, which separated Lancashire from Yorkshire, serving to isolate Liverpool and to keep back from her the flow of trade and commerce from industrial centres on the other side of the hills which should otherwise have regarded Liverpool as their natural port. The canal was further intended to open up more fully than had been done before the great coal-fields of Lancashire, ensuring a better distribution of their mineral wealth both to Liverpool and to the manufacturing towns of Lancashire; while, by connecting with the Aire at Leeds, the capital of the Yorkshire woollen industry, the canal was to provide another cross-country connection, by inland navigation, between Liverpool and Hull. The work of constructing the Leeds and Liverpool Canal included (1) the piercing of the Foulridge Hills by a tunnel, 1640 yards long, which alone took five years of constant labour; (2) an aqueduct bridge of seven arches over the {180}Aire; and (3) an aqueduct carrying the canal over the Shipley valley. The total length of navigation was 127 miles, with a fall from the central level of 525 ft. on the Lancashire side, and of 446 ft. on the Yorkshire side. The entire work of construction extended over 41 years, and the total cost was £1,200,000. The effect of the Leeds and Liverpool Canal on the industrial districts of Lancashire and Yorkshire was no less remarkable than the effect of the Grand Trunk Canal on the industries west or south of the Trent. When the Leeds and Liverpool Canal was formed there was, as Baines observes in his "Lancashire and Cheshire," not one town containing 10,000 inhabitants along the whole of its course from Liverpool to Leeds. With the improved facilities afforded for the conveyance of raw materials and manufactured goods from or to the port of Liverpool came a new era for the textile trades all along the route of the canal--and the now busy and well-populated towns of Wigan, Blackburn, Nelson, Keighley, Bradford and Leeds are indebted in no small degree for their industrial expansion to the better means of communication which the Leeds and Liverpool Canal, in the days when railways were still far off, opened up to them. Still another canal that was made in order to establish a line of communication west and east, and to serve important intermediate districts, was the Rochdale Canal, which starts from Manchester, rises by a succession of locks to a height 438 ft. above the Manchester level, and, fed on the hill summit by some great reservoirs, descends to the river Calder at Sowerby Bridge, the point from which that river is navigable to the Humber.