631 



period they took place, and what time the formation of certain por- 

 tions of the earth's crust required ; whereby some hght may be thrown 

 on those changes which lie beyond the limits 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 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 which 

 it included, and the philosophical manner in which its copious ma- 

 terials were arranged, well justified the distinction which it received. 

 The view presented in it of the great changes which have 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 judgement 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 en- 

 deavoured 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 HofF conceives that the island of Otaheite is under- 

 going a gradual elevation out of the sea.* Finally, the third volume of 

 this work appeared after an interval of ten years, in 1 834 ; 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 Thuringia" 

 * Part II. Pref. p. xir. 



