Supplementing these considerations as to the physical configuration of the country is the further fact that in the colliery districts the keeping of the canals in working order involves great trouble, incessant watchfulness and very {306}considerable expenditure on account of subsidences due to coal-mining. In my book on "Canals and Traders" (P. S. King & Son) I have told how "throughout practically the whole of the Black Country, the Birmingham Canal, for a total distance of about eighty miles, has been undermined by colliery workings, and is mainly on the top of embankments which have been raised from time to time, in varying stages, to maintain the waterway above the level of the ground that has sunk because of the coal mines underneath." Many of these embankments, as I have had the opportunity of seeing for myself, are now at a height of from twenty to thirty feet above the present surface of the land, and in one instance, at least, the subsidences have been so serious that an embankment twenty feet high and half a mile long has taken the place of what was formerly a cutting. If the Birmingham Canal had not been controlled by the London and North-Western Railway Company, who are under a statutory obligation to keep it in good and effective working condition, it would inevitably have collapsed long ago. No independent canal company, deriving its revenue from canal tolls and charges alone, could have stood the heavy and continuous drain upon its resources which, in these circumstances, the canal would have involved; and like conditions apply to various other railway-owned canals in the north, in Wales, and elsewhere. Concerning the Glamorganshire Canal, it is said in "Transport Facilities in South Wales and Monmouthshire," by Clarence S. Howells:[50] "The present owners have spent £25,000 on the canal since 1885 in an ineffectual attempt to revive its waning fortunes. One of its many difficulties is the subsidence caused by colliery workings." Dealing with the general position in regard to canal transport in the United Kingdom, J. S. Jeans remarks in "Waterways and Water Transport" (1890):-- "The railway companies have been accused of acquiring canal property in order that they might destroy it, and thereby get rid of a dangerous rival. This is probably not the case. The railway companies are fully aware of the fact that water transport under suitable conditions is more economical than rail transport. It would therefore have suited them, at the {307}same rates, to carry by water heavy traffic, in the delivery of which time was not of so much importance. But the canals as they came into their possession were naturally unadapted for such traffic without being more or less remodelled, and this the railway companies have not attempted.