It was plainly impossible to consider, in a candid and philosophical spirit, the argument with which I had to deal, so long as I remained ignorant of the evidence on which it was based. I resolved, therefore, to make myself familiar with the leading principles and the leading facts of Geology. And thus I was drawn insensibly into the study of this science; to which I have devoted, for some years, the greater part of my leisure hours. Impressed with the conviction that no fact can be really at variance with Revealed Truth, I determined, in the first place, to ascertain the facts which have been brought to light by the researches of Geologists. The general principles, which might afterward appear to be clearly involved in these facts when duly classified and arranged, I was fully prepared to admit. And I hoped, in the end, to search out and discover the harmony which, I was satisfied, must exist between conclusions thus established and the Inspired Word of God. While occupied in working out this problem for myself, it was suggested to me that others, who had not time or opportunity to pursue the same line of inquiry, would, perhaps, be glad to share in the fruits of my studies. In deference to this suggestion I consented, not without misgivings, to write a series of papers on Geology in its relations with Revealed Religion, which have appeared, from time to time, in the _Irish Ecclesiastical Record_. From the attention these papers attracted, crude and fragmentary as they were, it soon became evident that the question was not without interest for a large class of readers. And I have been led to believe that a more full and mature, but at the same time a popular, Treatise on the subject would be a welcome accession to ecclesiastical literature, and would supply a want that has long been felt. Such a Treatise I have proposed to myself in the present Volume. * * * * * In Geology I wish to disclaim at the outset, all pretension to original researches; which my opportunities did not permit, nor the scope of my Work demand. It was not my object to enlarge the bounds of Geological knowledge; but rather to ascertain what that knowledge is, and to set it before my readers in plain and simple words. For this purpose I have had recourse to the great masters of the science: and have endeavored to gather into a systematic form the phenomena upon which they are all agreed; to sketch in outline the general theory about which there is practically no dispute; and to draw out the line of reasoning by which, as it seems to me, this theory may be most effectively demonstrated.