Over the Irwell from Water Street is the entrance to the Manchester, Bolton & Bury Canal. Landmarks Canals Before 1750, roads were an impractical way of transporting heavy goods and water transport on the rivers was the accepted method. The number of suitable rivers was limited. Power to drive machinery was also derived from water but this needed fast-flowing streams where a head could be built up to turn the waterwheels. Finding the two types of water at the same locality was rare. Castlefield could use the River Medlock, as it fell to join the River Irwell to turn the wheels, but the Irwell needed to be improved to make it a safe river to navigate. Eight locks were constructed between 1724 and 1734, along the Rivers Irwell and Mersey; this was known as the Mersey and Irwell Navigation. Short cuts were dug to eliminate the difficult bends. Wharfs were built at Manchester Wharf, Water Street in 1740, and if the wind was not in the east small boats could travel from there to the sea. The navigation was subject to continuous improvement and was eventually superseded by the Manchester Ship Canal. The Bridgewater Canal was commissioned by Francis Egerton, 3rd Duke of Bridgewater, to transport coal from his mines in Worsley to Manchester. It was built by James Brindley and is the world's first true industrial canal, and Britain's first arterial canal. It opened to Castlefield in 1761 and fully to Liverpool in 1766. Castlefield was the Manchester basin, and it was watered by the River Medlock. The actual river was culverted under the basin and emerged by Potato Wharf, then flowed into the Irwell at Hulme Locks. The basin also was watered by ground water runoff, and in times of heavy rain, a weir was needed to maintain the water level. Brindley built a clover leaf-shaped weir which was replaced by the Giant's Basin. Today this appears as a 7-metre-deep, 7-metre-wide circular sump, crossed by an iron footbridge. The basin allowed other goods to be transported into the city such as cotton (from 1784) and building materials, and food. In 1802 the Rochdale Canal joined here at Duke's Lock, lock 92; this was the first canal to cross the Pennines; it brought with it clean water from its feeder reservoir at Hollingworth Lake. It connected with the Ashton Canal and the Peak Forest Canal bringing building limestone from