/**/LIX. The Reports of Mr. WILLIAM SMITH, and Mr. EDWARD MARTIN, to the Bristol and Taunton Canal Company, on the State of the Collieries at and near Nailsea, in Somersetshire.
The Committee of Proprieters under an Act of Parliament passed last sessions, for the Bristol
and Taunton Canal, in Somersetshire; having resolved, in June last, to take the opinions of two
eminent mineral surveyors , whether the coalfield around Nailsea, across which their line of
canal is to pass, was likely to furnish such a supply of Coals, as by the tonnage on them, to pay
interest to the proprieters for the expense of executing this part of their line, about eight
miles in length from the river Avon at Morgan's Pill, near Bristol, with a branch to the eastward
of about two miles in length, to Nailsea collieries: I am happy in being able to present the
Reports of these two gentlemen, conceiving that they will be read with interest by a considerable
class of my subscribers: and I beg to solicit the communication of similar documents, from time
to time, respecting other coal and mining districts.
GENTLEMEN, - Agreeably to your order of the 13th of June, requesting my assistance to examine and report on the probability of a sufficient quantity of coal at Nailsea, and the neighbourhood, to induce the Company to proceed with the canal from Morgan's Pill to Nailsea, immediately; I am happy to state that my Survey of those works has been highly satisfactory and, that a sufficient quantity of coal may thence be obtained, is more than probable.
This coal district is of much greater extent than is generally imagined, and, like the great coal-field at Newcastle-upon-Tyne, becomes flatter in the deep than at the outcrops. From this favourable position of all the coal (which I have most clearly ascertained), and from the great difficulties which were likely to happen, with respect to water, being successfully encountered by the engines lately erected, there can be no doubt of the permanency of the works. From the extraordinary hardness of the roof, and the easy working of the coal, I have no doubt but the Nailsea Pits will produce the quantity stated.
In my Survey of the Backwell Common Works, I also found many favourable circumstances belonging to those veins of coal, which cannot fail to make the collieries established on them, of long duration. The veins are of sufficient thickness to produce a great quantity of coal, without going over much ground. There are also a sufficient number of veins lying one beneath another, within a moderate depth from the surface, so as not to require the too frequent repetition of the great expense of new pits and machinery. The veins also lie so moderately inclined, as to be for a long period of years within the reach, of such shafts as may be sunk, by the help of steam engines, which, from the small quantity of water, in a great extent of coal already working, have not yet been found necessary. As the sinkings through the strata lying over these veins of coal are all soft and mostly impervious to water, it may be reasonably expected that the veins which lie under these will have still less water.
The surface of the land, to a great extent around these collieries, (at Backwell Common) is a tenacious clay, quite unabsorbent, and altogether unlike the land at Nailsea; and although the veins are thinner, there are more of them, and the coal is of a harder and better quality. The disadvantages which these works have experienced, from the quantity of timber required, will lessen with the depth to which the veins are worked, and the expense of procuring such timber will be lessened by making the canal. Although these veins of coal have been worked for a long time, the works have been carried on in such a small way as not materially to have reduced the quantity of coal, or to render the working of the the deep coal anywise dangerous, from water contained in the old hollows. The whole of the water between the pits and the outcrops is known, and daily exhausted, without the aid of pumps, and, in fact, all the coal that has ever been worked out of these veins, has been merely along the outcrops; and instead of exhausting the veins, or of rendering the deep works dangerous, they have most satisfactorily proved the great extent to which such works may be carried.
These veins appear to underlay the Nailsea veins; and it is highly probable that other veins between them remain undiscovered. At these pits, (Mr. Water's and Mr. White's) there are large stacks of good coals on hand: if these works in their present state are capable of thus overstocking the sale, there can be no doubt of what they will produce, when all of them are in full working. Besides the pit which is now working at Nailsea, there is another nearly down to coal, and old ones are kept open, which may be very readily cleaned up, and brought into use, either by opening gangways from the bottoms of them to the deep coal, or by sinking them deeper to work the under vien, which is quite unwrought, except by a few shallow pits along the outcrop, and which were drained by a level through Mr. Davis's tan-yard.
From the singularly advantageous position of the Nailsea coal, which I have clearly ascertained, and the quantity of water which can come to the pits, being also clearly known, either from the hollows of old workings, or the vast extent of coal which can be worked, and that quantity of water being kept down, and rapidly decreasing in all parts of such an extensive coal-field, by the power of the present engine, proves most clearly that such a colliery, worked to its utmost extent, can never be drowned.
From duly considering all these circumstances, I am fully satisfied, of the great extent to which these collieries may be worked; and have no hesitation in stating, that the Bristol and Taunton Canal Company may, with the greatest safety, proceed with the immediate execution of their canal to these collieries, with full confidence of thence obtaining tonnage sufficient, to pay a good interest on their expenditure.
15, Buckingham Street
York Buildings, London
[Vide rough sketch of Nailsea Colliery, in annexed Section No. 1, Plate IX] the thickness of the veins or seams being as follows; viz.
|1st vein . . . . . .||4½ feet|
|2d ditto . . . . . .||2|
|6½ feet of coal, in all.|
From which it may be seen, that the position of the strata and veins of coal, which are near the north crop, as at (a. a.), rise out very rapidly, but which moderate materially in going down southward in the deep; for at the 50 fathoms Engine Pit, which is the deepest point this vein has ever been sunk to, and but very little coals have been worked at that depth, the fall or dip of the strata is only from seven to eight inches in the progressive yard, or as near as may be, a dip of one in five; and I have no doubt but that the strata and veins of coal dip less and less as they run southward, as down (b b.), and soon afterwards rise gradually southward, as up (c c.). I am confirmed in this opinion from two corroborating circumstances.
1st. On examining the ground from Nailsea Colliery, along the surface line (d d.) southward to Chelvy, Youngwood, &c. I observed in the Quarries, and other places where the rock was bare, that the strata rose southward; and if the common strata do so, the veins of coal must do so too, for they are parallel beds.
2d. It has been observed in the neighbourhood of (e e.), that the water in some of the Wells has been drained off at times, when the water in the 50-fathom Engine Pit was quite out; and that when an accident happened to the engine, so as to occasion the water of the colliery to rise a considerable height in the pit, the wells were also filled again. This proves a subterraneous communication, and which is effected through the means of a very hard rock (intersected with chinks and chasms) which lies in a great thickness, immediately above the main vein of coal, through which the water is perpetually flowing in great abundance, to the large engine in the 50-fathoms pit. This thick hard rock, at the same time that it forms a most substantial strong roof to the main vein of coal, certainly lets loose an immoderate quantity of water to the fire-engine the pumps of which are 18 inches; but I do not wonder at this large flow of water, at the depth of about 50 fathoms; for I am well aware , that the surface water in coal countries, in general, is let in from gravel banks, or from loose matter connected with the surface, which often overpowers the means opposed to it, and which cannot be conquered but by additional machinery. This once done to a considerable extent, as to depth, greater depths may be sunk to and worked, without much risk of pricking water. The principal colliery at Whitehaven, the property of Lord Lonsdale, dipping directly to and under the sea, is drained close to the sea , at the depth of 80 fathoms; and the same vein is pursued to, and worked under the sea, to the depth of 150 fathoms, where so much water is not met with, as would suffice for the wetting of the underground tram-roads, which is the case in all other situations where collieries are worked to very great depths. I merely mention these circumstances, on account of the above engine being heavily laden with water, at the depth of 50 fathoms only, and to show that it is no uncommon case. When other collieries are open on the same vein to the westward, viz. on Nailsea and Kenn Moors, they will partake of this colliery water, which seems to follow a particular stratum of very hard jointy rock.
As to White's colliery, which lies to the north and north-east of Messers. Grace's Colliery, at Nailsea; the veins which are known here, break out to the north of the Nailsea Colliery, and naturally lay perpendicularly under the same. The following are the number and thickness of the veins, with the depth to which they have been sunk down and worked.
[Vide White's Colliery, in annexed Section No. 2;] where the thicknesses are as follows, viz.
|1st, King's hill vein . . . . . .||2 feet|
|2d, Main vein . . . . . . . . . .||3½|
|3d, Dungey vein . . . . . . . . .||2|
|7½ feet, in all.|
As to Backwell Colliery, [vide No. 3, in annexed Section,] the property of Mr. Teague, partly his own estate, and partly that of the Marquis of Bath; the thicknesses are as follows, viz.
|1st, Vein (of Smith's coal) .||2½ feet|
|2d, Vein . . . . . . . . . . . . . .||3|
|3d, Ditto . . . . . . . . . . . . .||1½|
|4th, Ditto . . . . . . . . . . . . .||3|
|5th, Ditto . . . . . . . . . . . . .||2|
|12 feet, in all.|
As to the veins of coal which lie parallel one under the other in a limestone basin, (which
is the case with all the veins of coal in the coal countries that I am aquainted with*)
[Vide annexed Section No. 4; where G. W. and T. show the places of the supposed southern crops of Grace's, White's and Teague's veins, repectively.]
This section shows the position in which the sundry veins of coals lie in the ground, and exactly in a parallel direction with the substratum in the limestone. I have already pointed out two proofs at Nailsea colliery, of the veins and strata becoming flat in the deep, and afterwards rising southward; and if the Nailsea veins really do so, there can be no matter of doubt of all the other veins of coal and strata, acting and laying in the same manner. There is also positive proof, that the limestone takes a dip from the north side, (where the same is observable at Belmont, Wraxall, and Clevedon Court) to the southward; and from the south side to dip northward, observable at Backwell Village, at Chelvy, Mr. Piggott's &c.; which proves the uninterrupted continuity of the limestone all the way underneath.
No. 5, is a rough sketch plan of the north and south limestone,
which contains the veins of coal, in the range from Backwell collieries to Nailsea, Nailsea-Moor,
Kenn-Moor, and the inclosed lands westward, from thence to the sea, where
a a. are Messrs. Grace's veins of coal at Nailsea, dipping southward.
b b. are the supposed crops of the same veins, dipping northward.
c. is the east end of the crops of the same veins, dipping northward.
d d. are the crops of White's veins, dipping southward.
e e. are the supposed south crops of the same veins, dipping northward.
f. is the supposed east crop of the same veins, dipping westward.
g g. are the Backwell veins, dipping southward.
h h. are the supposed south crops of the same veins, dipping northward.
i. is the supposed east crop of the same veins, dipping westward.
And the centre or hollow of the supposed basin is along the dotted line l l l.
The north, the south, and the east outcrops of these veins are here delineated; but the west crops cannot be ascertained, for the basin seems to widen very much going westward. It is not a mile wide on the surface at A. There is no doubt, I think, of each having a west outcrop, but it may be at many miles distance, under the sea, where the veins of coal may have increased in number as the basin became more extended; and as the level course of the veins and strata run nearly west or down channel, they cannot take land and be seen again in Glamorganshire, &c.
Very large new collieries may be opened on Nailsea Moor, the property of Sir Hugh Smyth, Bart.; on Kenn Moor, the estate of Lord Paulett; under the lands of Sir Abraham Elton, Bart., near Clevedon church, where the Backwell veins, worked by Mr. Teague, must range. The proposed collieries on Kenn Moor, which is about the main line of the Canal, will be two miles nearer to Morgan's Pill than the Nailsea, for the canal branch to Nailsea appears to be about two miles in length.
There are ten veins or seams of coal already discovered within this limestone basin; which added together make 26 feet of solid coal. These ten veins worked in the usual way, will yield 30,000 tons of coal per acre; but as some of them are thin, being under two feet, I will only calculate upon 20,000 tons per acre, and on working 400 tons per day, and on 300 working days in the year.
Consequently 400 tons x by 300 days, make 120,000 tons per annum.
And again, I will only estimate upon 1,000 acres, containing upon an average the whole of the ten veins, though I have no doubt but there are 2 or 3000 acres. Therefore 1,000 acres x by 20,000 tons per acre, give 20,000,000 of tons, and 20,000,000 divided by 120,000 tons per annum, gives 166 years, which is the length of time the colliery would last, at 120,000 tons per annum.
The distance from Morgan's Pill to Nailsea Collieries I understand is ten miles, and the tonnage authorised to be received by the act for making the Canal is 2d. per ton per mile; so that every ton is 20d. which on 400 tons per day, and on 300 days in the year, amounts to 10,000l. per annum, being equal to 10 per cent. on a capital of one hundred thousand pounds. This is about the sum the estimate is made for; but from what I observed of the line of canal, it is all good ground and easy cutting (excepting the Tunnel), and I think the whole ten miles should be completed for, from 70,000l. to 80,000l.
All the Nailsea Colliers are much interested in promoting the canal scheme; that is to say, in getting the canal brought from Morgan's Pill to the vicinity of their works; for till that is done, their sales of coals are so small, that the moneys arising from what is sold to the country, will hardly pay for carrying the works on, particularly where heavy engines and machinery are required.
The Committee of Management should require the Nailsea colliers to put their works in such a state and condition, as to insure the working of 500 tons of coals per day at the least, as a sort of guarantee to the canal proprietors for the risk of laying out immediately about 100,000l.
Messrs. Grace and Co.'s Colliery is heavily loaded with water, and by pricking additional feeders it would be drowned out; another Engine should be put up, to place them on a tolerable certainty. White's Colliery seems to be better off in regard to water, and a new engine of considerable power is erecting on the deep work.
At Teague's Colliery very little water has hitherto been met with, but in sinking deeper and in extending the work in every direction, feeders of water will surely be pricked, and that colliery cannot be considered out of danger till a fire engine is erected upon it.
The proposed collieries on Kenn-Moor, on Nailsea-Moor, and also on the lands of Sir Abraham Elton Bart., to the southward of Clevedon church, should be opened.
(Signed) EDWARD MARTIN
Morriston, near Swansea,
July 31, 1811