welldale, and Littondale; again crossed Hardflask and Malham moors; walked down Airedale to Skipton; and by Bolton, Blubberhouses, and Harrogate, traced the divisions of the millstone grit.

In the course of so many pedestrian journeys most of the high mountains have been ascended, and nearly every valley explored; the thicknesses of the strata having been ascertained by above one thousand barometrical observations.

I hope the preceding sketch of my proceedings will be thought to justify my publication; the nature of the subjects investigated, the necessity of close personal investigation of so many hills and dales, combined with that want of leisure, which so fatally retards the progress of men devoted to science, must be my apology for the long delay of its appearance.

I turn with pleasure to record the assistance which has been furnished me by several friends, whose names are not mentioned in the preceding pages. The mines of Greenhow hill were described to me on the spot by Mr. Nathan Newbold and Mr. Watson; Mr. Barratt supplied me with notes of those at Grassington, Mr. Stagg obligingly answered some queries concerning the mines which are under his able direction in Teesdale, and additions to my knowledge of the veins of Aldstone moor and the neighbouring districts were received from Mr. Sopwith, Mr. N. Wood, Mr. H. L. Pattinson, and Mr. Wm. Hutton. Notices of the limestones of Craven have at different times been communicated to me by Mr. Preston of Flasby, and Mr. Hamerton of Hellifield Peel; Mr. Yorke of Bewerley afforded me every facility for my inquiries in Nidderdale; Mr. Wheeler of Barnard Castle, Mr. Rutter of Middleton in Teesdale, Mr. Jonathan Otley of Keswick, and the late Mr. Bland of Hilton, have given me local information. My best thanks áre due to Mr. Hodgson of Lancaster, for prompt and complete information respecting the curious coalfield of Ingleton and Burton.

I am greatly obliged by the prompt attention of Mr. Gibson of

Hebden Bridge, and Mr. Francis Looney of Manchester, in sending specimens of many fossils from new localities in the limestone shale of the vale of Todmorden. Mr. Cooke forwarded for inspection the results of his researches in the vicinity of Hesket and Wigton, and Dr. Moore several select specimens for comparison and engraving.

But my greatest obligation is to MR. GILBERTSON of Preston, a naturalist of high acquirements, who has for many years explored with exceeding diligence and acumen a region of mountain limestone remarkably rich in organic remains. The collection which he has amassed from the small district of Bolland is at this moment unrivalled, and he has done for me, without solicitation, what is seldom granted to the most urgent entreaty; he has sent me for deliberate examination, at convenient intervals, THE WHOLE OF HIS MAGNIFICENT COLLECTION, accompanied by remarks dictated by long experience and a sound judgment. He had proposed to publish an account of his discoveries, and especially of the Crinoidea for which no man in Europe had equal materials, and had made a great number of careful drawings for the purpose; but all these, as well as the specimens, he placed at my disposal-a striking proof of liberal and genuine devotion to science.

An attentive examination of this rich Collection rendered it unnecessary to study minutely the less extensive series preserved in other cabinets. The Yorkshire Museum contains a considerable number of fossils from the limestone districts, chiefly presented by Mr. Danby, Mr. C. Preston, Mr. Kirby, Mr. Smith, Mr. Salmond, Mr. Roundell, the Rev. D. R. Currer, Mr. Hamerton, the Rev. W. V. Harcourt and myself. The same Museum contains a fine suite of fossils from the Northumberland limestones presented by the Rev. C. V. Harcourt. The Collections of the Natural History Society of Newcastle-on-Tyne have also been of great service to me. In addition to these advantages my own cabinet has furnished a few rare species; most of the figures of fossils are taken from specimens in Mr. Gilbertson's Collection, because these were generally the best that could be found.

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Very few and slight notices concerning this district have reached the Philosophical Societies of Yorkshire; the maps of Mr. Smith and Mr. Greenough are still the only graphical representations which can be consulted, (for Mr. Hall's Lancashire map only reaches the border of Craven,) and the memoirs of Professor Sedgwick and Dr. Buckland on the Penine chain, of Mr. Winch on the Geology of Northumberland and Durham, and of Professor Sedgwick and Mr. Hutton on the Whin sill, with my own Essays in the Geological Transactions and Encyclopædia Metropolitana, contain nearly all the geological information that has been even partially given to the public.šņa odt die on,daca a #dq I IZ bell mrbatoabites but an

Mr. Nixon has inserted in the Philosophical Magazine and Annals, some of the results of his exact trigonometrical and barometrical mea sures of the Yorkshire mountains; these, combined with the results of the Ordnance Survey and some of my own measures, will be found under the proper head. The labour of reducing my numerous barometical observations was lightened by the assistance of my friend Mr Wm. Gray, jun. ad morta

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I acknowledge with pleasure the useful information which I have received concerning the metalliferous veins of Cornwall from Mr. Hen wood, and those of Flintshire from Mr. Jolin Taylor.

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It has been my wish, to make just mention in the preceding notices of every individual who has accompanied me in my walks or in other ways specially aided my work; those who have in a less direct man ner interested themselves in the publication are by far more numerous, including nearly all the eminent cultivators of geological science. Among these I may be permitted to signalize one, the most competent of all men to have undertaken the description of this his native district, and whose labours on the borders of it rank among the best efforts of English' geology. Professor Sedgwick's examinations of the North of England have the same date as my own; we met for a few moments near the High force in 1822; after ten years of independent research we com pared results at Cambridge, and I found with great satisfaction that my

conclusions, drawn chiefly from examining the interior of the district, were consonant to those of my distinguished friend derived chiefly from the western border.

1

A valuable contribution to the philosophy of geology, by Mr. Hopkins, has just been printed for the Cambridge Transactions, and it is with extreme, gratification that I find the deductions from mechanical principles, as to the direction and other circumstances of the fissures and displacements of rocks, contained in this interesting Essay, perfectly in accordance with the inferences or laws of phenomena to which observation had conducted me. Had Mr. Hopkins's demonstrations in Geological Dynamics, been known to one before the Chapter on Subterranean Movements, (p.199,&c.) was printed, my views could not have been adduced, as it appears to me they ought now to be, in confirmation of his very important conclusions. The remarkable result arrived at by the tabulation of my observations on the Symmetrical Structure of Rocks, (Chap. iii. p. 90.) of two positive and two negative axes of fissure, the axes of each pair respectively perpendicular to one another, was totally unexpected when the table was composed, and no other observations or investigations for the same object being published, prudence suppressed speculation; but I do not think the causes of the symmetry represented in the Diagram p. 98, beyond the scope of Mr. Hopkins's researches,

The excellent work of The Messrs. Sowerby, entitled the Mineral Conchology of Great Britain; Martin's Petrificata Derbiensia; Parkinson's Organic Remains; Miller's and Cumberland's works on the Crinoidea; Dr. Ure's Rutherglen; and some figures of Orthoceratites communicated to the Annals of Philosophy by Dr. Fleming; contain nearly all the graphical representations of mountain limestone fossils accessible to the English reader.

It was important to supply this deficiency, by a large series of characteristic figures; and it is with a sense of real obligation that I mention the name of Mr. Lowry, who, in engraving from my draw

ings, has exhibited not only distinguished talent and judgment, but a patient and vigilant attention peculiarly valuable to one whose leisure hours are so few as mine.

To the numerous friends of geological science who have subscribed for the publication of this Work, unfeigned thanks are due: the personal favour conferred on the Author he gratefully acknowledges; but a higher feeling is involved in the spontaneous patronage which has been conferred on this record of his exertions, by individuals not specially interested in the results. These disinterested promoters of science know that without such aid and sympathy many costly works would never have appeared; many of the discoveries of the present age would be unknown to the next; and the progress of knowledge would be fatally retarded.

The noble aspiration of Wordsworth

Enough, if something from our hands have power

To live, and act, and serve the future hour,

is peculiarly applicable to the labours of men of science; and it is with a full sense of the importance of the trust which has been reposed in him for this object, that the Author of the Illustrations of the Geology of Yorkshire delivers the conclusion of his Work.

YORK, March 1, 1836.