518 Geological Society. 



and depth ; or when the circuit is small, lagoon islands: — how, again, 

 the same corals, when the land rises, are carried into elevated situa- 

 tions, where they remain as evidences of the elevation. We have 

 had placed before us the map, in which Mr. Darwin has, upon evi- 

 dence of this kind, divided the surface of the Southern Pacific and 

 Indian oceans into vast bands of alternate elevation and depression ; 

 and we have seen the remarkable confirmation of his views in the 

 observation that active volcanos occur only in the areas of ele- 

 vation. Guided by the principles which he learned from my distin- 

 guished predecessor in this chair, Mr. Darwin has presented this 

 subject under an aspect which cannot but have the most powerful 

 influence on the speculations concerning the history of our globe, to 

 which you, gentlemen, may hereafter be led. I might say the same 

 of the large and philosophical views which you will find illustrated 

 in his work, on the laws of change of climate, of diffusion, duration 

 and extinction of species, and other great problems of our science 

 which this voyage has suggested. I know that I only express your 

 feeling when I say, that we look with impatience to the period when 

 this portion of the results of Captain Fitz Roy's voyage shaU be pub- 

 lished, as the scientific world in general looks eagerly for the whole 

 record of that important expedition. 



And I cannot omit this occasion of mentioning with great gratifi- 

 cation, the liberal assistance which the Government of this country 

 have lent to the publication of the discoveries in natural history which 

 Mr. Darwin's voyage has produced. The new animals which he has 

 to make known to the world will thus come before the public de- 

 scribed by the most eminent naturalists, and represented in a manner 

 worthy of the subject and of the nation. I am sure that I may ex- 

 press the gratitude of the scientific world, as well as my own, for this 

 enlightened and judicious measure. . 



I may here notice Mr. Darwin's opinion, so ably exposed in a 

 paper read before us, that the change by which a variety of materials 

 thrown on the earth's surface become vegetable mould, is produced 

 by the digestive process of the common earth worm*. 



I will here also advert to Mr. Fox's paper on the process by which 

 mineral veins have been filled up. This he conceives might be pro- 

 duced by the circulation or ascension of currents of heated water 

 from the deeper parts of the original fissures. The discovery of the 

 causes of the formation and filling of metallic veins, one of the earliest 

 subjects of geological speculation, will remain probably as a problem 

 for its later stages, when our insight into the laws of slow chemical 

 changes is far clearer than it is at the present day. 



If, from these proximate causes of change of which I have spoken, 

 we proceed to those ulterior causes by which such events as these 

 are produced; — to the subterraneous machinery by which islands 

 and continents appear and vanish in the great drama of the world's 

 physical history ; — we have before us questions still more obscure, 

 but questions which we must ask and answer in order to entitle our- 

 selves to look with any hope towards geological theory. Of late 



[* See present vol. p. 89.] 



