"Great Britain ... has a range of high land passing nearly its whole length, which divides the springs and rain waters that fall to the opposite coasts: we shall call this range dividing the eastern and western rivers of Britain the grand ridge.... No less than 22 of our canals now do or are intended to pass this grand ridge, forming as many navigable connections between the rivers of the east and west seas!... The Dudley canal crosses this grand ridge twice, the two ends being on the eastern side, and the middle part on the western side thereof; the Kennet and Avon crosses the eastern and western branches, into which it divides on the Chalk Hills, west of Marlborough, by which parts of this canal are in the drainage of the west, the south and the east seas! The Coventry Canal, also, by means of its Bedworth branch, crosses the grand ridge twice. The populous and remarkable town of Birmingham is situate on high ground, near to the grand ridge, and has six canals branching off in different directions, either immediately therefrom or at no great distance, and, what is singular, owing to a loop, or sudden bend of the ridge at this place, no less than five of them traverse the grand ridge, either by means of tunnels or deep-cutting."
While the grand ridge here in question presents no difficulty to powerful locomotives, the position is altogether different with canals fed by streams of water that will not flow up-hill. In the case of the Birmingham Canal, specially referred to in the extract just given, there are three separate "levels." The lowest is 209 feet, and the highest 511 feet above sea level. Boats doing the cross-country journey, or passing between Birmingham and the coast, would have to overcome such heights as these by means of locks, lifts or inclined planes.
Here we have a very different proposition from that which is presented by canals on the flat surfaces of Holland, Belgium and North Germany—with, also, their abundant water supplies, from great rivers or otherwise—whereas the upper levels of the Birmingham Canal are kept filled with water only by means of costly and powerful pumping machinery, supplemented by reservoirs.
When the original builders of canals had to cross the grand ridge, or any other elevation over which they required to pass, they sought to economise water consumption and to keep down both cost of construction and working expenses by making the locks on the top levels only just large enough to pass boats of a small size. The dimensions of any boat making a through journey are thus controlled by those of the smallest lock through which it would require to pass. On lower levels where the water problem did not arise—or not to the same degree—the locks could well be made larger, to accommodate larger boats engaged only in local traffic.
The material differences in cost of construction and operation between waterways on a low and uniform level and those crossing considerable eminences, by means of locks, were well recognised by Parliament when approving the lists of tolls to be paid on different waterways. On the Aire and Calder the minimum toll, if a boat passed through a lock, was fixed at five shillings. On the Rochdale Canal the minimum toll for a boat crossing the summit level was ten shillings.[[49]] The reason for this difference is that whereas the Aire and Calder navigation is but little above sea level throughout, the summit of the Rochdale Canal is at a height of 600 feet above sea level, and is crossed by means of ninety-two locks in thirty-two miles.
The reader will see, therefore, that the want of a common gauge in the construction of artificial waterways, mainly designed, at the outset, to supply the needs of particular districts, may often have been due to more practical reasons than simply a lack of combination or a difference of view on the part of canal constructors, the problem of gauge on canals built at varying elevations, and all depending on water supply, being entirely different from any question as to the gauge or the running of railways on the same or similar routes.
"The necessity of a uniform gauge on canals as on railways," says Clifford, "is now clear enough. We need not wonder that, in the eighteenth century, Parliament was no wiser than the engineers, and had not learned this lesson." It was, however, not entirely a matter of wisdom. There were, also, these inherent defects of the canal system itself to be considered. It is very doubtful if even Parliament, had it possessed the greatest foresight, could have forced, or have persuaded, the canal companies to construct locks of precisely the same dimensions at elevations of 400, 500 or 600 feet, where water was difficult to get or costly to pump, as on canals more or less on the sea level, and deriving an abundant water supply from mountain streams or navigable rivers.
Forbes and Ashford, in "Our Waterways," also think it is much to be regretted that in this country no standard dimension was ever fixed for canals, "as has been done in France." But the superficial area of the United Kingdom, with its mountains and valleys, and hills and dales, presents a wholly different problem, in the matter of canal construction, from that offered by the flat surfaces of France, of Holland, of Belgium or of North Germany. In 230 miles of waterway between Hamburg and Berlin there are three locks. In this country there is an average of one lock for every mile and a quarter of canal navigation. The total number of locks is 2,377, and for each of these there must be allowed a capitalised cost of, on an average, £1360.
The fate that overtook the once prosperous canals of South Wales when the railways could no longer be suppressed by the canal companies, and were allowed to compete fairly with them, has been materially due to their own physical disadvantages in respect of the large number of locks they require to overcome the steep inclines of the mountainous district in which they were made. These facts are brought out in the Fourth (Final) Report of the Royal Commission on Canals and Waterways, where it is said:—
"The Glamorganshire and Aberdare Canals were bought by the Marquis of Bute in 1885. They form a continuous narrow waterway with a total length of about 32 miles. In this distance there are 53 locks.... The waterway is used at the Cardiff end by small coasting vessels, but above this point the traffic has fallen off considerably. The total tonnage carried on the canals amounted in 1888 to 660,364 tons; in 1905 to 249,760 tons. Two railways run parallel to the canals and carry almost all the coal brought down from the collieries near the canals. The gradients from these collieries to the port are considerable. This makes the haulage of full railway trucks easy, and, on the other hand, in the case of the canal makes necessary a great number of locks relatively to the mileage, with consequent slowness of transport.