ADVENTITIOUS SHELLS. CHANGE OF SHALE. ALUM. in our mineral country. It is a greasy substance, of an agreeable smell; and I fuppofe afcribed to the benign part of those imaginary beings. It is efteemed ferviceable in rheumatic cafes, rubbed on the parts affected. It retains a place in our Dispensary. I SHALL juft mention two or three adventitious bodies difcovered at vast depths in our mines. We have been often furprised with finding great rude logs of timber, at the depth of twenty-five or forty-five yards under ground. They are quite rough, and totally freed from any fufpicion of having been used in the mines, even had they not been met with in new or unworked ground, in blue clay, and amidst tumblers. They are firm and strong when first taken up, and of a black color, as if they had been burnt. SHELLS, especially concha anomia, are very common, fometimes loose, but more frequently immersed in the lime-stone. I Now quit the heights, and go down a steep defcent, about half a mile, into the lower part of the parish. The mouth of a level, and a fhallow fhaft near it, difcovers the change of ftrata. The chert and the lime-ftone quite difappear, and in their place appear first the beds of shale, black, fhattery, and foon diffoluble when exposed to the weather. It is the fymptom of approaching coal, and the covering. Cronstedt, i. 259, calls it a pyritaceous fchiftus, and gives it other epithets, according to its contents. It is often found in beds of immenfe thickness, and often filled with inflammable air, which frequently bursts out to the great inconveniency and danger of the workmen. It is alfo impregnated with bitumen, which adds to its powers. In many parts of the kingdom it is found to contain quantities of alum; and and to be worked for the purpose of extracting from it that useful article. The trial is worth making. In our parts we have the fame advantages of coal for the procefs, and water-carriage for the exportation, as Whitby has. Coals begin to appear in their unprofitable beds, at a small distance to the east; half a mile further, in great bodies, and of an excellent quality. THE collieries of Moftyn and Bychton have been worked for a very confiderable space; and in the last century supplied Dublin and the eastern fide of Ireland with coals. They were discovered in the township of Moftyn, as early as the time of Edward I. as appears by an extent of that place, in the twenty-third year of that reign. I REMEMBER many fluctuations in their state. They are now in the most flourishing which I ever remember, inferior only to that in which they were in the latter end of the late, and the beginning of the prefent century. The rife of the collieries at Whitehaven, which interfered with our trade to Dublin, was one caufe of their decline; but another great caufe was a natural one, the lofs of the channel of the river. Dee. We still load a few small veffels for the neighboring coafts of North Wales. But our prefent profperity arifes from the great works of copper-plates, bolts, and fheathings for fhips, and the works of brass established of late years near the town of Holywell. To them may be added the confumption occafioned by the increase of population, by the acceffion of the cotton manufactures; and, finally, the vast quantities used for burning of lime, the effect of the happy inprovement in agriculture, annually increafing for numbers of I do not mention our obligations to the numerous fmelting-houfes for lead, as they have been established among us, during time immemorial, years. I RE COLLIERIES. QUAY. ENGINE. STRATA. I REMEMBER a quay beneath the Moftyn collieries, built by the THIS engine feems to have been formed on the model of fome STATA IN THE BYCHTON COLLIERIES. 4 |