nature. Over the roof is a large quantity of pyritous shale, which occasionally burns spontaneously for a long time, producing a singular appearance, not unlike that which may be seen sometimes near Newcastle, where the slack or small coal is left in heaps at the pit-mouth.

Fig. 2.--Section across the thick coal and lower seams in the Aubin coal-field.

8

7 6

Level of the valley.

Some of the seams worked in this basin are of very unusual thickness, but all appear subject to great and sudden variations. In one mine (les Etuves) the coal is as much as fifty yards thick where worked, and as the whole of this is near the surface (see 1, fig. 2) and above the level of the valley, it is found possible to pare away the surface and remove the coal by a process analogous to quarrying. The actual quantity of available coal in this seam in the Aubin concession cannot be less than 10,000,000 of tons, all above the valley; and the same bed, though disconnected, is repeated at intervals, and is worked in the Decazeville valley.

Two other seams (Fournal (3) and Bois Nègre (4), fig. 3) measure together no less than thirty-eight yards in thickness, and there are others from two to ten yards each where worked. The beds less than four or five feet thick are not even named. It must, however, be borne in mind that the thickness is not the same over any length of section, although the seams themselves appear constant *.

* The following are the names and average thicknesses of the different seams whose relative position may be judged of by the sections (figs. 2 & 3) in the text:

No. 1. Les Etuves (Pelonie haute)

Yds. Ft.

2. Pelonie basse

4

3. Fournal

16

4. Bois Nègre

21

5. Fraysse No. 3 (Montet No. 1) (Bussonie No. 1)...........
6. Do. No. 2 Do. No. 2) ( Do.

No. 2)..

5

7. Do. No. 1 Do. No. 3)

8

8. Passelaygue (Bezelgues)....

10

The quality of the coal is variable, but generally sufficiently good for manufacturing and household purposes. The thick coal (les Etuves) burns with a long flame, and is valuable for domestic use; the twenty-yard seam cokes well, and would be valuable for locomotives, and for the manufacture of iron; some parts of it also yield a fair per-centage of gas. The Passelaygue (ten yards thick) is greatly valued as an excellent coal for the forge. It is clean and moderately hard, but is interstratified with a small band of shale and pyrites, making it desirable to wash the coal before coking.

Fig. 3.-Section acros the middle seams of the Aubin coal-field.

5 6

The various seams have been hitherto worked on a system which may be described as a convenient combination of the pillar and stall with the long-wall method, a small proportion of coal only being left behind, and very little timber used. The cost of extraction is very moderate, and it is distinctly proved that any quantity of mineral can be brought to bank at a cost varying from a shilling to twenty pence per ton of twenty hundredweight.

A few bands of iron ore certainly occur in these coal-measures, but none have yet been worked, and it is very possible that when attention is drawn to this subject, other and thicker layers may be found.

The south-eastern portion of the Aubin coal-field is covered up with beds of the triassic period, which are soon succeeded by soft red sandstones and oolitic limestones. Near Marcillac, the sandstones contain marls in which a considerable amount of copper has been found, chiefly in the form of a small gravel of malachite pebbles. The coal reappears in this direction on the edge of the crystalline rocks in one or two places before reaching Rodez. At this point several pits have been sunk and mines opened.

The Rodez basin (somewhat improperly so-called) consists of a series of beds of coal dipping heavily to the north, reposing on the schists and gneiss or granite of the Aveyron district on

the south, and covered up almost immediately, first by new red sandstone rocks of no great thickness, and then by hard calcareous beds of the liassic period. An extensive and important series of oolitic limestones next succeeds, and ranges for a great distance.

The ground where the coal crops out consists of a series of hills of some elevation flanking the crystalline rocks, and occupying part of the narrow space between them and the river Aveyron. The length of the crop is about six miles from Rodez to Laissac, but the coal reappears near Severac, a distance of about fifteen miles from Rodez, and is supposed to be continuous throughout. I saw no distinct proof of this, although it is by no means unlikely, and indeed there is little doubt that beneath the secondary rocks the coal-measures will ultimately be traced at intermediate points round the whole of the eastern side of the granite and gneiss of Aveyron from Aubin by Rodez, Severac and St. Afrique to St. Gervais, Graissesac, and the other coal-fields already known in the south.

The breadth of the Rodez coal-field as determined by the outcrop of beds of the carboniferous period is extremely limited. Of the coal-seams there are four described, but only two or at most three appear worth working. These vary in thickness from three to as much as eighteen feet each, but cannot, I think, be calculated on as having in all a greater mean total thickness than twelve feet. The middle part of the crop appears to have the thickest beds, but these do not extend many hundred yards without becoming nipped to about a third of their dimensions. The total distance between the crystalline rocks and the new red sandstone does not much exceed half a mile, and hitherto there has been nothing absolutely proved beyond that limit. The beds incline at angles varying from 30° to 60°, and the principal bands of coal are within a thickness of 100 yards of measures. The lines of outcrop, though really continuous, are difficult to trace, and the actual relation they bear to each other is imperfectly made out over most part of the field.

I considered it important to obtain an estimate, however general, of the total quantity of available coal in these concessions, and I therefore made the necessary calculations for the purpose. Owing to the great irregularity in thickness of the different coal-seams, and the very considerable slope of the beds, the

result is small compared with other concessions of anything like equal extent. I cannot anticipate a larger quantity than sixteen millions of tons as the available produce of the district I visited for all the seams, if worked to a depth of 150 fathoms below the water level. It will be understood that the absolute exhaustion of the field to this extent could not take place without a number of deep pits, each provided with all requisite machinery for extraction, and must take considerable time. From any single pit in this district some time must elapse before a quantity of coal amounting to 100 tons per day could be properly taken, as the whole of the preliminary works are yet to be commenced.

The first aspect of the Rodez coal is unfavourable, as it has a stony, dirty appearance and bad colour; but on further examination and actual trial, it proves to be much better than could be supposed. It burns freely with a moderately long flame and much heat. It does not die out rapidly, or consume quickly; and though the proportion of ash is not small, it is by no means excessive. It cokes well, and in large, compact and clean-looking pieces, and the coke, made after washing the coal, would certainly be well adapted to the manufacture of iron. The proportion of coke is about sixty-six per cent. of the washed coal. The present average cost of getting the coal and bringing to bank is considered to be nearly 3s. per ton. The cost of the coke properly made from washed coal would not be less than 7s. per ton.

The concessions brought under my notice include almost the whole of the field from Rodez to Laissac, a distance of between five and six miles. In most places the coal has been got by shallow pits, and foot-rails or small levels run in upon the coal at its crop. As much as could be carried off thus without timbering, shafts, or cross-cuts, has been already removed, and the result has been to some extent injurious to the upper part of the remaining coal. A large quantity of coal might, however, still be obtained by deeper adits entering in some places from the valley of the Aveyron, although no extensive mining operations could be carried on without arrangements being made for deep sinkings, in which it is not unlikely that there would be a large quantity of water *.

* Since my visit I learn that the coal has been lately reached by a shaft sunk through a moderate thickness of the new red sandstone, and that it is

C

The principal employment of the Rodez coal has hitherto been for local purposes, such as lime-burning, and for domestic use in the neighbourhood, and the average annual supply from the Bennac mine, the only one at present in work, is about 4500 tons. The greatest amount that has been taken from this mine in a day is sixty tons, nor does the system of working admit of greater development.

The profit has been large in proportion to the amount of sales, being in fact almost equal to the expenses. There is, however, little capital invested, and the cost of management is extremely small. It must be borne in mind that no opportunity exists for greatly increased development, as the demand is nearly, if not quite, supplied, and the market would hardly admit of any addition to the quantity without a reduction of price, nor even then to any great extent, unless the means of communication are improved.

The one great resource for this, as for all the adjoining coal basins, is the establishment of railway communication with the principal towns of the South of France. It is proposed to bring a branch of the Great Central Railway (the main line of which is now in course of construction) to the town of Rodez, and in this case all the coal property would become very valuable, as iron ores are abundant at no great distance.

The chief sources of iron ore to supply the Aubin and Decazeville furnaces, and others in these coal districts, consist of thick and widely extended deposits in the limestone rocks immediately adjacent, belonging to the oolitic period. There are also large quantities of other kinds of ore, valuable for mixing, brought from various places within a radius of twenty or twenty-five miles. Amongst these is a rich and valuable hydrous oxide from Perigord, and some other very rich peroxides combined with silica, from Lunel.

The jurassic rocks on both sides of the Aubin coal-field are remarkably rich in ferruginous deposits in the limestone. At Veuzac, near Villefranche, are two beds, each a yard thick, nearly horizontal, and close to the surface. The cost of getting is less than fifteen-pence per ton. The ore is partly pisolitic, and the beds are traceable on the surface for five or six miles.

much more horizontal and of better quality there than in the mines of Bennac, the nearest point at which it crops. This discovery greatly increases the value and importance of the mineral field.