Description of the Coal-field under the Firth of Forth. 341

I trust, in conclusion, that my object in the foregoing remarks may not be misunderstood. The results are purely theoretical, and from what has been shewn, they are very liable to mislead in practice, if applied to comparing different kinds of fuel. On the other hand, if used for determining the comparative steam-raising power, or the thermal effect, of different specimens of coal, for instance—that is, of different varieties of the same kind of fuel-they are doubtless of considerable value. I have shewn sufficiently why the theoretical effects cannot be obtained in practice, but with the same kind of fuel, be it wood, peat, coal, charcoal, or coke, the specimen or variety which, submitted to the foregoing tests, exhibits the highest results in theory, may safely be considered the best practically, and therefore, when properly applied, such calculations afford a useful means of determining the comparative commercial value of fuel.

Description of the Large Coal-field under the Firth of Forth. By Mr DAVID LANDALE, M.E.* (With a Plate.)

The Secretary having asked me to read a paper for this session, and the President of the Geological Society having made the same request, it occurred to me that this subject was suitable for both Societies, giving the geological portion to the one body in the shape of a memoir, and the engineering or proposed means of working and winning the field, to the Royal Scottish Society of Arts. The first portion was read last month, and I now proceed to lay the other half of it before you, divested of much of the geological detail.

When we consider the important part which Scotland now plays in the coal trade of great Britain, furnishing fully one-seventh of the whole, I hope the subject will be one of . some interest to the Fellows of the Society.

From the statistics furnished by Robert Hunt, Esq., keeper of the mining records at the Museum of Practical Geology, Jermyn Street, London, we find that for the last nine years the coal produce of Great Britain was as follows:

* Read before the Society on 22d February 1864, and awarded the special thanks of the Society. 2 x

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From which it appears, from 1854 to 1862 the output has increased from about 64 to 81 millions per annum, showing an increase of production equal to 2 millions per annum, the total production on the whole globe being calculated at 128 millions per annum.

Scotland has more than kept pace with the rest of the kingdom; in the first five years of that period her proportion. was fully one-eighth, and for the three years ending in 1862 it has increased to nearly one-seventh of the total output, as will be seen by the preceding figures.

The exciting discussions in Parliament upon the commercial treaty with France, and the great diversity of opinion given by eminent men on that occasion, has created a great interest in this matter, and data are now being collected to get at reliable information on the subject. Mr Hull, one of the officers of the Geological Survey, published a book on the subject in 1861, of which a second edition has been called for. It contains a vast amount of important information as to the stores of coal, its consumpt, and rate of exhaustion. Mr Hull takes 4000 feet, or a depth of 666 fathoms, as the limit of mining operations, and at this great

depth he makes out that there is a store of coal still in Great Britain to last 1000 years; and for Scotland he gives a supply of 25,323 millions, or 2450 years, with a vend of 10 millions, but as that vend is now fully 11 millions, it follows it will only last 2300 years; and I hope to show you that we have another 900 millions of tons, or 81 years' supply, scarcely scratched near our own doors, which Mr Hull has not taken into his calculations at all. He brings out that certain districts of the coal-fields are much nearer exhaustion than others, such as Lanarkshire, Northumberland, and Durham, and several others, and when these are done we shall have to supply our neighbours to a much greater extent than we have yet done.

There is a general resemblance between the coal-fields of Fife and the Lothians, although the seams have different names, as will be seen from the following sections constructed by me in 1851, and also by looking at the coast sections. One of the sections of the Fife coast made by me in 1838 represents the coal strata as known to exist along the Fifeshire coast. The East Lothian coast will be found on the Ordnance section of recent date, showing most of the coal-seams along the shore on this side of the Forth in the two basins of the Esk and Cockenzie ; but as many seams do not reach the coast, and the coals have different names at different places, they are not all exhibited on that section. The following printed vertical sections may therefore be taken as the best for shewing the stratigraphical position of the several coal beds.

I have endeavoured to identify the several seams on each side of the Forth by numbering them on the margin of each.