PREFACE. THE circumstance of a work like the present proceeding from a Professor of Chemistry seems to call for some explanation; for notwithstanding the near connection that subsists between the latter Science and every Department of Geological inquiry, yet it must be confessed, that the Study of Volcanos embraces in itself a field of such extent, that it ought to be entered upon as a principal, rather than as a subordinate occupation. It is fair therefore to myself to mention, that the subject was first taken up at a time, when there appeared a reasonable prospect of my obtaining an appointment, which would have entailed the necessity of a five years absence from my native country. The appointment in question I indeed ultimately lost, owing, as it was understood, to certain doubts that had been started with regard to my eligibility as a Candidate ; but, as I had already formed the plan, and in some degree advanced in the details of the enquiry, I continued to prosecute it at intervals, not only for several years after my hopes of the situation alluded to had been frustrated, but even at a time when the office I afterwards obtained in the University of Oxford might have rendered a somewhat dif ferent line of pursuits more appropriate. I have been obliged however in consquence to curtail in a considerable degree the scheme I had formed, which comprehended originally an examination of the Volcanos in the New, as well as of those in the Old World; and am under the necessity of now bringing forwards as a compilation, many parts of the work in which I had intended to introduce nothing but original matter. It is satisfactory for me however to reflect, that I have visited most of the principal localities in Europe, noticed in my two first Lectures as the seats of volcanic action, so that with respect to them, even where facts are stated which did not fall within the compass of my own observation, I have been able to ascertain by going over the same ground, what degree of credit is due to the individuals on whose authority they are given. In treating of the other Quarters of the Globe in which Volcanos occur, I have spared no pains in availing myself, to the best of my ability, of those resources, which a proximity to extensive public libraries has placed at my disposal, and therefore hope that this part of the work at least may be of use to future travellers; not merely by putting before them what is already ascertained, but likewise by directing their attention to those points which still require investigation. I venture therefore to offer these Lectures as supplying in some degree, even in their imperfect state, a deficiency long felt in the geological literature of Great Britain; no treatise on the subject of Volcanos having appeared in this language since that of the Abbè Ordinaire, except indeed the recent publication of Mr. Poulett Scrope, which, though containing many ingenious views on the theoretical parts of the subject, is not calculated to supersede the demand for another work, expressly designed to convey a detailed statement of facts, with regard to the characters and situation of the rocks which owe their origin to subterraneous fire. I have only further to add, that the remarks, made at the commencement of the First Lecture, with respect to the little attention that has been paid in Great Britain to the Department of Geology, which forms the subject of this work, must be understood as applying solely to that portion of it, which relates to Products confessedly Volcanic; for in no country has more important light been thrown on the nature of Trap and Basaltic Districts, than by the labours of Dr. Macculloch and of other English Geologists; to some of whom I feel personally indebted, either for much of the information which forms the ground work of such an enquiry, or for the friendly assistance afforded me in the prosecution of it. See particularly the Memoir on the Coast of Antrim, by my friends the Rev. W. Buckland and W. Conybeare, in the Third Volume of the Geological Transactions, Supplementary to Dr. Berger's paper on the same district. |