By arguments such as these the opposition actually checked for some years the carrying out of several important undertakings, including the Trent and Mersey Navigation. But, when once the movement had fairly started, it made rapid progress. James Brindley's energy, down to the time of his death in 1772, was especially indomitable. Having ensured the success of the Bridgewater Canal, he turned his attention to a scheme for linking up the four ports of Liverpool, Hull, Bristol, and London by a system of main waterways, connected by branch canals with leading industrial centres off the chief lines of route. Other projects followed, as it was seen that the earlier ventures were yielding substantial profits, and in 1790 a canal mania began. In 1792 no fewer than eighteen new canals were promoted. In 1793 and 1794 the number of canal and navigation Acts passed was forty-five, increasing to eighty-one the total number which had been obtained since 1790. So great was the public anxiety to invest in canals that new ones were projected on all hands, and, though many of them were of a useful type, others were purely speculative, were doomed to failure from the start, and occasioned serious losses to thousands of investors. In certain instances existing canals were granted the right to levy tolls upon new-comers, as compensation for prospective loss of traffic--even when the new canals were to be 4 or 5 miles away--fresh schemes being actually undertaken on this basis. The canals that paid at all paid well, and the good they conferred on the country in the days of their prosperity is undeniable. Failing, at that time, more efficient means of transport, they played a most important rôle in developing the trade, industries, and commerce of our country at a period especially favourable to national advancement. For half a century, in fact, the canals had everything their own way. They had a monopoly of the transport business--except as regards road traffic--and in various instances they helped their proprietors to make huge profits. But great changes were impending, and these were brought about, at last, with the advent of the locomotive. The general situation at this period is well shown by the following extracts from an article on "Canals and Rail-roads," published in the _Quarterly Review_ of March 1825:-- "It is true that we, who, in this age, are accustomed to roll along our hard and even roads at the rate of 8 or 9 miles an hour, can hardly imagine the inconveniences which beset our great-grandfathers when they had to undertake a journey--forcing their way through deep miry lanes; fording swollen rivers; obliged to halt for days together when 'the waters were out'; and then crawling along at a pace of 2 or 3 miles an hour, in constant fear of being set down fast in some deep quagmire, of being overturned, breaking down, or swept away by a sudden inundation.