But along with the improvement of roads other schemes were being developed which ultimately led to the formation of the navigable canals which now intersect the county. The first of these is the one known as the Bridgewater Canal, which was commenced in 1758, when the Duke of Bridgewater obtained power to construct a water way from Worsley to Salford and to Hollinfare (or Hollin Ferry), on the river Irwell, and also to carry his canal across that river through Stretford into the town of Manchester. This work, which was then considered a masterpiece of engineering, was carried out under the direction of James Brindley. In addition to the aqueduct over the river, which is upwards of 200 yards long, there were other difficulties to be overcome, amongst them a tunnel of three-quarters of a mile in length. The bridge over the Irwell consists of three arches, the centre one 63 feet wide and 38 feet high, thus admitting barges to go through with masts standing, and, as Baines put it (writing in 1836), affording the spectator the "extraordinary sight, never before witnessed in this country, of one vessel sailing over the top of another." In 1761 a much bolder scheme was commenced by the Duke, which, when completed, formed a canal nearly 30 miles long, from Stretford to Runcorn on the Mersey. This took five years to construct, and it had the effect of at once lessening the cost of carriage by water between Manchester and Liverpool by at least fifty per cent. But this first Lancashire canal was not used only for the conveyance of goods; boats on the model of the Dutch _trekschuyt_ were used daily to take passengers from Manchester to the places on the line of route. A branch from Worsley to Leigh was cut in 1795. Before the establishment of canals powers had been obtained in 1720 to render navigable the Irwell and Mersey from Liverpool to Manchester, and in 1726 the river Douglas (_alias_ Asland), from Wigan to the Mersey. These river improvements were made at great cost, and at the best were not found to work in a very satisfactory manner, and were soon superseded by the ordinary canals. One of the first Lancashire canals was the Leeds and Liverpool, which was begun in 1770, when it was considered one of the boldest schemes which had ever been undertaken in England. Its length from Leeds to Liverpool is 107 miles. Dr. Aiken, writing near the close of the century, says of this canal: "On a cursory survey, the tract of country through which it passes will probably appear not extremely inviting to such an undertaking. It is but lightly peopled, and though the great towns at the opposite extremities abound in objects of commercial importance, yet their connection with each other is not very intimate, nor does it seem likely to be much promoted by such a circuitous communication. Coal and limestone are the chief natural products of the intermediate country; and as the districts abounding in the one often want the