1866. | Our Coal Supply and our Prosperity. 465 
we cannot grant all that Mr. Vivian demands in his estimate of 
the resources of the great South Wales coal-field. Not one of 
Mr. Vivian’s mines in South Wales has reached one-half the depth 
of which he makes so small an account, and yet he must have a 
tolerable experience of the difficulties and outlay of mining by 
machinery even to the moderate depth of 400 or 500 yards. If 
it were taken for granted that because the coal is there it must 
be accessible, the Royal Commission would not be needed. 
Let us now ask: Are we likely to procure a supply from below 
the sea, or estuaries of Great Britain ? 
The districts in which coal-measures extend under the sea are 
certainly few, considering the large areas the coal-fields occupy in 
the land. We cannot expect any great addition to our supply 
from these tracts, as it is evident the entrance to the mines must 
be always above the limit of high tides. In Cumberland, Flint- 
shire, and a few other places, coal has been worked under the sea 
with success for many years—one of the mines af Whitehaven 
extending 3,200 yards from the shore. In Scotland the coal 
formation constitutes the sea-board of parts of Ayrshire, Fifeshire, 
and the Lothians. In England we may expect a very large quantity 
of coal to be recovered under the sea between the north of the 
Tyne and the Tees, provided great care be taken to leave barriers 
for stopping off the waters for some distance from the outcrop of 
the seams downwards. We may also expect at some future time, 
coal to be wrought under the estuary of the Dee, and possibly that 
of the Mersey, and again along the coast of the Vale of Clwyd 
near Rhyl. But the most important tract is that which is covered 
by the waters of Swansea and Carmarthen Bays. In the latter 
case many hundreds of acres of the lower and most important seams 
are under water, and we shall not be surprised if, at some future 
time, steps be taken to reclaim from the ocean by embankments a 
sufficient extent of the estuary to allow of the recovery of the whole 
of the coal. 
To this inquiry let us add the parallel one: In what districts 
and under what formations may there be coal still undiscovered ? 
It is perfectly true, as stated by Mr. Vivian, that some of our 
coal-fields are merely outcropping portions of larger concealed coal- 
fields. If we take the Lancashire and Cheshire coal-field on the 
North, the Flintshire, Denbighshire, and Shropshire coal-fields on 
the West, the North Staffordshire coal-field on the East, and the 
South Staffordshire coal-field on the South, we inclose an enormous 
area under nearly the whole of which we may safely state that coal 
exists within a depth of 5,000 feet of the surface.* If we were to 
adopt a limit of 4,000 feet, the area would be considerably reduced, 
* See Map of the Coal-bearing Tracts of Great Britain, ‘ Quarterly Journal of 
Science,’ No. 1. Also, Hull’s ‘ Coal-fields of Great Britain.’ Second edit. 
