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Rh candor and sincerity, in abandoning old ground and embracing new views, that is afforded in the whole history of science. In the earlier editions of his works he accepted the current opinions in regard to organic species and the past course of life upon earth, but, after a half-century's study of the question, he became satisfied that these views are untenable, and in the tenth edition of his "Principles of Geology," published in 1867, he gave them up, and adopted the general view represented by Mr. Darwin. This great work he has again revised, and the eleventh edition has just made its appearance. All the later questions of this most interesting subject will there be found most ably and fully discussed. We subjoin the notice of the work just published by the Saturday Review:

The great work of Sir Charles Lyell has too long and too authoritatively held its place as a classic in the literature of science to call for, or even to admit, the expression of any estimate of its value. The number of editions it has gone through may be taken as sufficiently attesting the concurrence of public taste and conviction with the appreciative opinion of the more critical class of readers at home and abroad. It may be hoped that the wide and increasing circulation of so valuable a work has had, and is long destined to have, the effect of leavening the mass of educated thought with its sound, careful, and conscientious views of physical truth. While congratulating both the writer and reader upon the issue of the eleventh edition of the 'Principles of Geology,' we feel that our notice of its contents is almost of necessity restricted to those portions of the work in which the author has seen reason to amplify, to remodel, or to correct, what he had advanced in former impressions.

Within the last five years special attention has been drawn to the geological proofs of strongly-marked changes in the terrestrial climate during long periods of time. In face of the additional facts and corresponding theories which have thus divided the minds of geological inquirers, Sir Charles Lyell has seen fit to recast those chapters of his work which treated of the meteorology and climatic history of the earth's surface, with a view especially to insist upon the paramount influence exerted in this direction by the relative distribution and height of the land at successive periods. The balance of argument and research has been such in the mean while as to confirm him more and more in his conviction of the agreement and continuity of the forces at work through all the vicissitudes of the earth's surface, from the earliest to the most recent geological ages. It is hardly necessary, perhaps, to go further back, for the pedigree of the organic forms which for the most part chronicle and attest the laws of succession, than to that Miocene period in whose organic deposits the flora and fauna of all subsequent ages seem to have their ground and root. A superficial view of the local changes of climate which are proved to have taken place might have, and indeed has, induced the belief that causes no longer