field covers a considerable portion of the counties of Cork, Limerick, and Kerry, but the seams of coal are comparatively few and of little value. The Munster coal field, however, is the most extensive in Ireland, occupying a workable area of one million square acres. The strike of the strata is east and west, as in the South Wales coal basin, and the dip to the south at an angle of forty-five degrees.

Coal has been wrought in the neighbourhood of Kanturk for nearly a century. In the Dromagh colliery four beds have been worked; the uppermost, three feet thick, is anthracite; and the two lower beds culmiferous deposits. In the neighbourhood of Cork and Waterford the thickness of the mountain limestone averages fifteen hundred feet, and the coal measures two thousand feet. Directly on the limestone occur black indurated shales, higher up these alternate with olive-coloured grits and flags, and among them or above them occur two or three bands of coal, together with abundance of coal plants. These coal measures are highly contorted and inclined, and often inverted; and the coals are not only changed into anthracite, but squeezed and crushed so as to be only got in small dice-shaped fragments. The regularity of the beds is also interfered with, so that beds of which the original thickness was probably a couple of feet, have now, for many yards, only one or two inches, and then suddenly expand into large pockets of coal; so that coal mining is here conducted like vein mining. Black limestones and shales also occur, containing Aviculo-pecten, Goniatites, Posidonia, &c., similar to those met with in the Lancashire coal field. Lough Allen, the source of the Shannon, is the centre of the Connaught coal district. This district contains two hundred thousand square acres of workable coal. Coal and iron have been worked at Arigna, and the iron was of good quality; but the badness of the roof was a serious impediment to the profitable prosecution of the works. The Ulster coal field commences near Dungannon, in the county of Tyrone, and extends in a southerly direction. The principal collieries in this field are at Coal Island and Dungannon. It is estimated to possess five hundred thousand square acres of workable coal, with eight seams, the thickest of which is six feet, averaging a total thickness of forty feet. The Leinster coal field is about eighteen miles in length, and six in breadth. It is situated in the counties of

*

*Jukes' "Manual of Geology."

Kilkenny, Queen's County, and Carlow, extending for a short distance into Tipperary. The coal of Kilkenny is nearly pure carbon, and the best seams vary from fifteen to eighteen inches in thickness. The extent in square acres is nearly one hundred and fifty thousand, possessing nine seams, and a total thickness of twenty-three feet of coal. Some of the old workings, which are of very high antiquity, manifest considerable mining skill, but no tradition exists in the neighbourhood even as to the time when they were wrought.

VI.-COAL DEPOSITS OF SCOTLAND.

These extend, though not continuously, over a distance in length of about one hundred miles, having a breadth of from thirty to forty. The total number of seams are from fifty to sixty that exceed a foot, but the average thickness throughout is about three feet and a half. The thickness of the whole measures is five thousand feet. The coal-field extending along the Clyde Valley, and through Lanarkshire, has a workable area of one million square acres, having eighty-four seams of coal, whose total thickness is nearly two hundred feet, the thickest seam being about thirteen feet. The Mid-Lothian coal-field has a total thickness of three thousand feet, comprising stratified beds of sandstone, shale, coal, ironstone, and limestone. The lower beds contain the Burdiehouse limestone, so famous for its organic remains. The coal seams in this group are tolerably numerous and valuable; the most important is the "North Green's seam," which varies in thickness from a few inches to fully five feet, and has been extensively worked for the Parrot, or gas-coal, which it contains. The Edge group contain about thirty seams of coal above a foot thick, and many more of less size; they occur irregularly, some lying only a few inches apart, and others from eighty to ninety feet. The Upper or Flat coal series occupy the centre of the basin, where the coals rest at a very low angle; hence the name of the group. These occupy the centre of the Mid-Lothian coal-field. The EastLothian field contains sixty seams of coal, which average a total thickness of one hundred and eighty feet, the thickest seam being about thirteen feet. There are also several other small areas; at Dumfries one occupies about 45,000 square acres, with ten seams of coal, whose total thickness is fifty-five feet. The total amount of coal supposed to exist in Scotland occupies about three

L

times the space of the Newcastle coal-field; the thickness of the available coals in them, however, is more than double.

DURATION OF OUR COAL SUPPLIES.

Great anxiety from time to time has been caused by the repeated question How long will our coal supplies continue? This question has again been exciting public, and, indeed, senatorial attention. The interest which was taken by every class of persons during the recent Parliamentary debates on this important subject, shows the amount of importance which is very properly attached to it; for everyone felt that upon the truthful answer to this question no small portion of our national prosperity depended. When it is remembered, too, that upwards of seventy million tons of coal are annually taken from our supplies, we cannot help feeling some degree of alarm. There have not wanted prophets of evil to foretell our approaching decline, although their account savours very much of the same style as Laplace's celebrated description of what would happen to the earth, if it should be struck by a comet. The most reasonable article which has appeared on this important subject is one written by Professor Ansted, on "Coal Fields and Coal Extraction;" although, perhaps, he takes too narrow a view of our fuel stores. He makes it out, from a rough calculation, that our stores of coal will last, at the present rate of consumption, about six hundred years! Without doubt this figure is extremely low, and, when compared with the estimates of other geologists equally celebrated, seems somewhat contradictory. Dr. Buckland states that the coal of the Newcastle coal-field will last for four hundred years. Mr. Bailey reduced this to two hundred years; but others of the coal owners, who were examined before the House of Commons in 1830, extended it to upwards of 1,700 years. "But the Newcastle coal-field, although it has been longest worked, is neither the largest nor the most important. The Lancashire district is as large, and has a far greater thickness of coal. The Yorkshire field is larger; but the coal beds are not so numerous, although some are thicker. The South Staffordshire is small, but the thickness of the coal is exceedingly great, amounting in some parts to between thirty and forty feet. The Somersetshire field is only one-half that of Newcastle; but the South Wales coalfield has both a much greater area, thicker beds, and more of them than it."* Taking, therefore, the estimate of Dr. Buckland respecting

*Ansted's "Geological Gossip," page 286.

the duration of the deposits in the Newcastle field, and comparing the rest from it, we should have a far greater period of duration than that assigned by Professor Ansted. By a later account the estimated extent of the coal measures of the United Kingdom, is six thousand square miles, or about four millions of acres. Assuming the average thickness of workable coal throughout this area moderately, at fifteen feet, as an acre contains 4,840 square yards, it would yield 24,000 cubic yards of coal: making a large reduction for waste, &c., and taking only one-third of this amount, at the average weight of one ton per cubic yard, each square mile of coal measures would yield five million tons of coal. The present annual expenditure of coal is estimated at the most about eighty millions of tons. Thus, every year, sixteen out of the six thousand square miles are being exhausted; and, at this rate, it will require fully three hundred and fifty years. And if we calculate the whole fifteen feet in thickness, it will take one thousand and fifty years to exhaust the coal-fields of Great Britain.

Another authority (one of the geological survey), has more recently stated, that, at the present rate of consumption, the coal beds of the United Kingdom will last upwards of thirteen hundred years. Mr. Bakewell also stated that the coal measures of the South Wales coal-field would supply the consumption of Great Britain for 2,000 years. (?) In all these calculations much has necessarily been deducted for waste, pillars remaining, dangerous state of mines from gases, stoppages by water, &c.; but we may reasonably expect that with additional discoveries and inventions, in connection with mining, much of this now necessary waste will be both saved and recovered, and thus the period of duration of our fuel stores be prolonged. Since the introduction of the "Davy" lamp, and improvements in pumping engines, and ventilation of mines, many mines formerly abandoned have been re-worked. At the same time, it behoves us as a nation, depending materially upon our mineral treasures, to know their value and extent, and to economise their resources.

What the future has in store for us we cannot tell; the past two centuries have done so much in the history of improvement and invention, that we may safely argue that the time is coming when fuel will perhaps not be the main spring of almost every occupation. Already we are enabled to weave by electricity; and it is well

known that the expansive properties of carbonic acid gas are sufficient to act as a motive power. Magnetism, Galvanism, and perhaps other "isms" yet to be discovered, will each be pressed into the cause of Progress. So long as the old Anglo-Saxon spirit of perseverance and industry is kept up, England will not fail in prosperity, neither will her sons lack influence.

From papers read before the Geological Society, of London,* it would appear that there is a possibility of reaching the carboniferous measures in the more southern counties, sooner than has been previously supposed. All the rocks of the secondary division have a tendency to thin out as they approach the mouth of the Thames, especially the new red sandstone.

The following tablef shows how the new red sandstone thin out southerly:

These facts may have an important bearing with regard to the depth of the coal under the south-eastern counties; and, as our northerly coal-fields become more exhausted, may not attempts be made, guided by the future progress of geology, to search in places where it would be now reckoned almost fruitless?

*

Quarterly Journal Geological Society, vol. 16. + Manchester Geological Transactions, vol. 2.

J. T.