But it is chiefly the neighbourhood of the sea which gives such an incomparable value to our most important coal-fields; as, thanks to this advantageous situation, which none of the French, Belgian, and German coal-fields possess, Great Britain is enabled to provide not only her own coast-towns, but almost all the sea-ports in the world, with a cheaper fuel than can be produced in their own country. Even in Ostend, Belgian coal, rendered dear by canal transport, is unable to compete with that which is brought over sea from England; and Hamburg provides herself with fuel from Newcastle and Hartlepool, and not from the coal-fields of Saxony and Westphalia.
Coal is found in seventeen counties in Ireland, over an area of about 3,000 square miles. Yet, notwithstanding this great abundance of coal which the country possesses, and which is distributed throughout almost all parts of the island, from Limerick to Antrim, her capital and chief cities and ports have hitherto depended upon Great Britain for their supplies of mineral fuel, both for domestic and for manufacturing purposes. To those who are unacquainted with the actual circumstances, it appears scarcely credible that this fine country has made so little use of the coal which has been so bountifully bestowed upon her. Among other causes not political, which perpetuate this state of things, is the extraordinary facility and cheapness with which the ports of Ireland can be supplied from the great western coal-fields of Great Britain. The excellence, abundance, and cheapness of peat, which is not only the common fuel of the poor in the interior, and, indeed, of all classes in some districts, but is also brought in barges by the great canal, and consumed to a considerable amount in the capital itself, is another reason why the Irish coal-mines have, as yet, been so little worked.
When we consider the vast importance of coal, we cannot wonder at the paramount influence which it has exercised over the distribution of our population in modern times. While Salisbury, Winchester, and Canterbury—important towns of mediæval England—are reduced to atrophy from the distance and absence of coal-fields, Newcastle, Leeds, Manchester, Sheffield, Birmingham, Glasgow, and a host of other flourishing towns may truly be said to be built on coal.
Where there are large coal-fields there is life and a prospect of almost unlimited prosperity, for they are sure to attract machinery and man. Take a geological map of a new and thinly-populated country; and if it be marked with coal-fields the spots where large cities will exist hereafter may be safely determined.
A more detailed examination of the chief coal-fields of England shows us the immensity of the mineral riches which are here still hoarded up for the benefit of future generations.
The superficial extent of the South Welsh coal-fields is about a thousand square miles. On its northern wing we find on an average twenty-one coal bands, forming an aggregate thickness of eighty and a half feet. In some parts of the south wing there are even as many as thirty-three bands of an aggregate thickness of one hundred and four feet of pure coal, so that the average depth of the field may be estimated at ninety-two feet.
Numerous transversal valleys intersect this magnificent coal-field, and afford the easiest means of working it in every depth. They also facilitate the transport of the coal on the canals and railroads which lead along their bottom or along their slopes to the harbours of the Bristol Channel. In the chapters on iron and copper, I have had occasion to describe the gigantic industries, founded on these natural advantages, which have raised South Wales from being one of the most insignificant into one of the most important provinces of the empire.
All the coals of this basin are so rich in carbon as to yield from seventy to ninety per cent. of coke. They are either anthracites or only semi-bituminous, and are consequently not suitable for making gas, nor are they much liked for burning in open fire-places, as they do not emit a genial flame. On the other hand, the semi-bituminous Welsh coal is invaluable for burning in steam-engines, for it has been proved to generate one-quarter more steam than any other kind of English coal. One of its properties—by no means unimportant—is its non-liability to spontaneous combustion, which, it is well known, occasionally takes place with bituminous coals, and by which vessels have been lost at sea, and warehouses ignited on land. The value of the Welsh steam or slightly bituminous coal is enhanced by its quality of burning almost without smoke, a property hitherto slightly appreciated, but the importance of which in time of war is evident. Steamers burning the fat, bituminous coal can be tracked at sea at least seventy miles, before their hulls become visible, by the dense columns of black smoke pouring out of their pipes or chimneys, and trailing along the horizon. It is a complete tell-tale of their whereabouts, which is not the case with vessels burning Welsh or anthracital coal. From its compactness and density, the latter has likewise great advantages in point of stowage space over the ordinary weak bituminous coals. For long voyages this concentration of power and economy of space may easily be appreciated. From its great superiority over other kinds, Welsh coal has been exclusively used for some time past by the French Government, and it is also employed in England by all the chief mail packet companies.
Coal is not exported from the South Wales basin as much as from some other fields, owing to the enormous requirements of the large iron works, most of which consume as much as can be supplied by their collieries. Every week, however, sees increased supplies of Welsh coal thrown into the London market, and every year fresh collieries are opened to meet the demand. The total number of pits in South Wales in 1865 was four hundred and eighteen, which produced between seven and eight million tons annually. The New Navigation Pit at Mountain Ash may be cited as an example of the grand scale on which the most important of these workings are conducted. The shaft is eighteen feet in diameter inside the walling, and divided into four compartments, two of which are for the drawing of coal, one for sending the workmen up and down, and the fourth for the drainage. Notwithstanding the great depth of three hundred and seventy yards, a carriage containing two half-tons of coal can be wound up in one minute, and the whole colliery is estimated to supply more than one thousand tons a day. The mineral property extends over an area of seven miles long by three miles in width, covering from four thousand to five thousand acres of four-foot coal. From this one case the reader may form a slight estimate of the boundless resources of the whole basin.
The Great Central Coal-field, which ranges through South Yorkshire, Nottinghamshire, and Derbyshire, has a superficial extent of about one thousand square miles. In character it is closely allied to that of Newcastle, and is considered by some geologists to be a re-emergence of the same strata from beneath the covering of the magnesian limestone under which they suppose it to be concealed through the intervening space. It extends a little from the north-east of Leeds nearly to Derby, a distance of more than sixty-five miles. Its greatest width—twenty-three miles—is on the north, reaching nearly to Halifax on the west. On the south it extends towards the east to Nottingham, and is there about twelve miles wide. Though possessing some fine coal-seams, it is of far inferior importance to the Manchester or South Lancashire Coal-field, from which it is separated by a lofty chain of hills. This highly valuable basin, which extends over about five hundred and fifty square miles, begins in the north-west of Derbyshire, and continues thence to the south-west part of Lancashire, forming an area somewhat in the shape of a crescent, having Manchester nearly in the centre.