Rev. Mr Whe well's Address to the Geological Society, 145 



principle to geology; and Mr Lyell has always been forward to acknowledge 

 his obligations to M. Von HofF. Indeed the idea of such an identification of 

 geological with historical changes was by no means new ; it had been both 

 expressed and acted on by Deluc ; and must have been present to the minds 

 of those persons who framed the question which gave rise to Von HofFs book. 

 This question was proposed in 1818 by the Royal Academy of Science of 

 Giittingen. " Considering^^ they said, " that we havCy in the crust of the earthy 

 evidence of great revolutions, which have happened at dlffersnt times, in different 

 portions, and of which the period and duration are unknown, we are led to ask^ whe-^ 

 ther certain more partial alterations may not lie within the domain of tradition, and 

 give us the means of knowing at what period they took place, and what time the f of" 

 mation of certain portions of the earth's crust required ; whereby some light may be 

 thrown on those changes which lie beyond the limit of history. ^^ 



M. Von Hoff 's work, — " The history of those natural changes in the 

 earth's surface which are proved by tradition'' — appeared (the first part) in 

 1822, and had the Academy's prize assigned to it. This part of the work 

 contained an account of the changes due to the agency of water ; and, by the 

 wide range of reading and study wliich it included, and the philosophic man- 

 ner in which its copious materials were arranged, well justified the distinction 

 which it received. The view presented in it of the great changes which hav6 

 gone on from the beginning of historical times, — the yielding or advancing 

 of coasts, the disappearing of islands, the union of seas, — appear to give a 

 new face to the globe. But the portion of the judgment of the Academy 

 which the author most valued, was that in which they said that he had used 

 the sources of his information conscientiously. In 1824 appeared the second 

 part, containing the history of volcanos and earthquakes ; and, although the 

 previous labours of Humboldt and Von Buch had done much to connect and 

 generalise facts of this kind. Von Hoff's labours were an important step : 

 " At least," he himself says, " he was not aware that any one before him had 

 endeavoured to combine so large a mass of facts with the general ideas of the 

 natural philosopher, so as to form a whole." Among other large views, we 

 may see much which, as to kind of change supposed, agrees with the opinions 

 of Mr Darwin, of which I shall have to speak ; for instance, Von HotF con* 

 ceives that the island of Otaheite is undergoing a gradual elevation out ot 

 the sea. * Finally, the third volume of this work appeared after an interval 

 often years, in 1834; in which he considers other causes of change; as rising 

 and sinking of the land ; alterations of rivers and seas ; the operations of 

 snow and ice ; and also the geological results to which the whole survey had 

 led him. In this volume he expresses his pleasure at the appearance of Mr 

 Lyell's work, which had taken place in the intervening period, and by which 

 he had found much new light thrown upon his own speculations. 



In the interval of time between the publication of the second and third 

 volumes, M. Von Hoff published " Geological Observations on Carlsbad' 

 (1825), and " Measures of Heights in and near Thuriniria" (1833). In this 

 last work, he not only gave a great number of his own barometrical measure- 

 ments, but discussed all extant measures of the heights of points in Thu* 



« Part II. Pi«r. p. xiv. 

 VOL. XXV. NO. XLIX.— JULY 1838. K 



