terials of older rocks, and from chemical precipitates,) on those lower spaces into which the detritus of ancient elevated regions was transported by the force of water; the second raising these strata from the sub-aqueous regions in which they were deposited, by forces analogous to those whose effect we occasionally witness in the tremendous movements of land, that form one of the phenomena of modern Earthquakes.

I am relieved from the necessity of entering into details respecting the history of the Coal Fields of our own country, by the excellent summary of what is known upon this interesting subject, which has recently been given in a judicious and well selected anonymous publication, entitled The History and Description of Fossil Fuel, the Collieries, and Coal Trade of Great Britain. London, 1835.

The most remarkable accumulations of this important vegetable production in England are in the Wolverhampton and Dudley Coal Field, (Pl. 65, Fig. 1,) where there is a bed of coal, ten yards in thickness. The Scotch Coal field near Paisley presents ten beds, whose united thickness is one hundred feet. And the South Welsh Coal Basin (Pl. 65, Fig. 2,) contains, near Pontypool, twenty-three beds of coal, amounting together to ninety-three feet.

In many Coal fields, the occurrence of rich beds of iron ore in the strata of slaty clay, that alternate with the beds of coal, has rendered the adjacent districts remarkable as the site of most important Iron foundries; and these localities, as we have before stated, (p. 65,) usually present farther practical advantage, in having beneath the Coal and Iron ore, a substratum of Limestone, that supplies the third material required as a flux to reduce this ore to a metallic state.

Our section, Pl. 65, Fig. 1, illustrates the result of these geological conditions in enriching an important district in the centre of England, near Birmingham, with a continuous succession of Coal mines, and Iron foundries. A similar result has followed from the same causes, on the north-east

frontier of the enormous Coal basin of South Wales, in the well-known Iron foundries, near Pontypool and Merthyr Tydfil,* (See Pl. 65, Fig. 2.) The beds of shale in the lower region of this coal field are abundantly loaded with nodules of argillaceous iron ore, and below these is a bed of millstone grit capable of enduring the fire, and used in constructing the furnaces; still lower is the limestone necessary to produce the fusion of the ore. Pl. 65, Figs. 1, 2.

The great iron foundries of Derbyshire, Yorkshire, and the south of Scotland, afford other examples of the beneficial results of a similar juxtaposition, of rich argillaceous iron ore and coal.

"The occurrence of this most useful of metals," says Mr. Conybeare,t"in immediate connexion with the fuel requisite for its reduction, and the limestone which facili

* In the Transactions of the Natural History Society of Northumberland, Durham, and Newcastle, vol. i. p. 114, it is stated by Mr. Foster, that the quantity of iron annually manufactured in Wales is about 270,000 tons, of which about three-fourths are made into bars, and one-fourth sold as pigs and castings. The quantity of coal required for its manufacture will be about five tons and a half, for each ton of iron. The annual consumption of coals by the iron works will therefore be about 1,500,000 tons. The quantity used in the smelting of copper ore imported from Cornwall, in the manufacture of tin plate, forging of iron for various purposes, and for domestic uses, may be calculated at 350,000 tons, which makes altogether the annual consumption of coal in Wales, 1,850,000 tons. The quantity of iron manufactured in Great Britain in the year 1827 was 690,000 tons. The production of this immense quantity was thus distributed,

tates that reduction, is an instance of arrangement so happily suited to the purposes of human industry, that it can hardly be considered as recurring unnecessarily to final causes, if we conceive that this distribution of the rude materials of the earth was determined with a view to the convenience of its inhabitants."

Let us briefly consider what is the effect of mineral fuel, on the actual condition of mankind. The mechanical power of coals is illustrated in a striking manner, in the following statement in Sir J. F. W. Herschel's admirable Discourse on the study of Natural Philosophy, 1831, p. 59.

"It is well known to modern engineers that there is virtue in a bushel of coals, properly consumed, to raise seventy millions of pounds weight a foot high. This is actually the average effect of an engine at this moment working in Cornwall.

The ascent of Mont Blanc from Chamouni is considered, and with justice, as the most toilsome feat that a strong man can execute in two days. The cumbustion of two pounds of coal would place him on the summit."

The power which man derives from the use of mineral coal, may be estimated by the duty* done by a pound, or

* The number of pounds raised, multiplied by the number of feet through which they are lifted, and divided by the number of bushels of coal (each weighing eighty-four pounds) burnt in raising them, gives what is termed the duty of a steam engine, and is the criterion of its power. (See an important paper on improvements of the steam engine, by Davis Gilbert, Esq. Phil. Trans. 1830, p. 121.)

It is stated by Mr. J. Taylor, in his paper on the duty of steam engines, published in his valuable Records of Mining, 1829, that the power of the steam engine has within the last few years been so advanced by a series of rapid improvements, that whereas, in early times, the duty of an atmospheric engine was that of 5,000,000 pounds of water, lifted one foot high by a bushel of coal, the duty of an engine lately erected at Wheal Towan in Cornwall, has amounted to 87,000,000 pounds; or, in other words, that a series of improvements has enabled us to extract as much power from one bushel, as originally could be done from seventeen bushels of coal. Thus, through the instrumentality of coal as applied in the steam engine, the power of man

any other given weight of coal consumed in working a steam engine; since the quantity of water that the engine will raise to a given height, or the number of quarters of corn that it will grind, or, in short, the amount of any other description of work that it will do, is proportionate to that duty. As the principal working of mineral veins can only be continued by descending deeper every year, the difficulty of extracting metals is continually on the increase, and can only be overcome by those enlarged powers of drain

over matter has been increased seventeen fold since the first invention of these engines; and increased nearly threefold within twenty years.

There is now an engine at the mines called the Fowey Consols in Cornwall, of which Mr. Taylor considers the average duty, under ordinary circumstances, to be above 9,000,000; and which has been made to lift 97,000,000 lbs. of water one foot high, with one bushel of coals.

The effect of these improvements on the operations of mines, in facilitating their drainage, has been of inestimable importance in extracting metals from depths which otherwise could never have been reached. Mines which had been stopped from want of power, have been reopened, others have been materially deepened, and a mass of mineral treasure has been rendered available, which without these engines must have been for ever inaccessible.

It results from these rapid advances in the application of coal to the production of power, and consequently of wealth, that mining operations of vast importance, have been conducted in Cornwall at depths till lately without example, e. g. in Wheal Abraham, at 242 fathoms, at Dolcoath at 235 fathoms, and in the Consolidated Mines in Gwennap at 290 fathoms, the latter mines giving daily employment to no less than 2,500 persons.

In the Consolidated Mines, the power of nine steam engines, four of which are the largest ever made, having cylinders ninety inches in diameter, lifts from thirty to fifty hogsheads of water per minute, (varying according to the season) from an average depth of 230 fathoms. The produce of these mines has lately amounted to more than 20,000 tons of ore per annum, yielding about 2,000 tons of fine copper, being more than one-seventh of the whole quantity raised in Britain. The levels or galleries in these mines extend in horizontal distance a length of about 43 miles. (See J. Taylor's account of the depths of mines, third report of British Association, 1833, p. 428.)

Mr. J. Taylor farther states, (Lond.` Edin. Phil. Mag. Jan. 1836, p. 67) that the steam engines now at work in draining the mines in Cornwall, are equal in power to at least 44,000 horses, one-sixteenth part of a bushel of coals performing the work of a horse.

ing which Coal, and the steam engine, alone supply. It would be quite impossible to procure the fuel necessary for these engines, from any other source than mineral coal.

The importance of Coal should be estimated, not only by the pecuniary value of the metals thus produced, but by their farther and more important value when applied to the infinitely varied operations and productions of machinery and of the arts.

It has been calculated that in this country about 15,000 steam engines are daily at work; one of those in Cornwall is said to have the power of a thousand horses,* the power of each horse, according to Mr. Watt, being equal to that of five and a half men; supposing the average power of each steam engine to be that of twenty-five horses, we have a total amount of steam power equal to that of about two millions of men. When we consider, that a large proportion of this power is applied to move machinery, and that the amount of work now done by machinery in England, has been supposed to be equivalent to that of between three and four hundred millions of men by direct labour, we are almost astounded at the influence of Coal and Iron, and Steam, upon the fate and fortunes of the human race. "It is on the rivers," (says Mr. Webster,)" and the boatman may repose on his oars; it is in highways, and begins to exert itself along the courses of land conveyances; it is at the bottom of mines, a thousand (he might have said, 1800) feet below the earth's surface; it is in the mill, and in the

* When Engineers speak of a 25 horse Engine, they mean one which would do the work of that number of horses constantly acting, but supposing that the same horses could work only 8 hours in every 24, there must be 75 horses kept at least to produce the effect of such an Engine,

'The largest Engine in Cornwall may, if worked to the full extent, be equal to from a 300 to 350 horse power, and would therefore require 1000 horses to be kept to produce the same constant effect. In this way it has been said than an Engine was of 1000 horse power, but this is not according to the usual computation.

Letter from J. Taylor, Esq.to Dr. Buckland,