"The River Irwell flows directly down from Bury to Manchester, and the river Croal, which flows through Bolton, joins the Irwell between Bury and Manchester; but neither of these streams was considered available, by any amount of improvement that could be given to it, for the purposes of navigation. They are both of them very impetuous streams, occasionally sending down immense torrents of water, but at other times so shallow as not to furnish sufficient depth of water for the smallest vessels. Instead, therefore, of wasting time and money upon them, a canal was cut at a considerably higher level, but following the general direction of the river Irwell."
The Manchester, Bolton and Bury Canal was thus a further example of the resort to artificial canals, with water channels capable of regulation, in preference to further schemes for rendering rivers navigable.
{ 185}How the situation brought about by the creation of the network of navigable waterways thus spread, or being spread, throughout the country was regarded by an impartial observer in the "Canal Mania" period is shown by the following comments thereon by Dr Aikin:--
"The prodigious additions made within a few years to the system of inland navigation, now extended to almost every corner of the Kingdom, cannot but impress the mind with magnificent ideas of the opulence, the spirit and the enlarged views which characterise the commercial interest of this country. Nothing seems too bold for it to undertake, too difficult for it to achieve; and should no external changes produce a durable check to the national prosperity, its future progress is beyond the reach of calculation. Yet experience may teach us, that the spirit of project and speculation is not always the source of solid advantage, and possibly the unbounded extension of canal navigation may in part have its source in the passion for bold and precarious adventure, which scorns to be limited by reasonable calculations of profit. Nothing but highly flourishing manufactures can repay the vast expense of these designs. The town of Manchester, when the plans now under execution are finished, will probably enjoy more various water-communication than the most commercial town of the Low Countries has ever done. At the beginning of this century it was thought a most arduous task to make a _high road_ practicable for carriages over the hills and moors which separate Yorkshire from Lancashire; and now they are pierced through by _three navigable canals_! Long may it remain the centre of a trade capable of maintaining these mighty works!"