Ixiv PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



produced changes in the earth's superficial temperature*, more 

 particularly with reference to its being assigned as an explanation 

 of the cold of the Glacial period, for which he proves it to be entirely 

 insufficient. Mr. Hopkins showed, at the same time, that more 

 might be said in favour of a maximum than of a minimum tempera- 

 ture acquired in this way, but yet that, if our sun were to approach 

 a star -v^dthin the distance of the planet Neptune, a case incompatible 

 with the continued existence of the solar system in its present form, 

 the stellar radiation would not send to the earth much more than 

 the thousandth part of the heat which she derives from the sun. 

 The inappreciable increase of temperature derivable from this source 

 renders the hypothesis untenable so long as the reasoning of our 

 lamented former President remains unimpugned. 



The subject of the climate of former periods as contrasted with 

 the present, and more particularly as connected with the phenomena 

 of the Glacial epoch, has been elaborately handled by our foreign 

 member Baron Waltershausen, Professor of Geology at Gottingen, 

 in a treatise t to which the prize of the Haarlem Society has been 

 awarded. His investigation reminds the reader of those sections of 

 Mr. Hopkins's paper on Changes of Climate which discuss the posi- 

 tion of the isothermals, the height of the snow-line under different 

 circumstances, and particularly the extent to which elevation of the 

 land in the Alps and in the Snowdon district may have caused the 

 former extension of glaciers. But my esteemed friend the Gottingen 

 Professor enters much more into the details of the geological phe- 

 nomena so closely intertwined with the meteorology and the mecha- 

 nics of the Alps, and brings to his aid the researches of other 

 authors, published within the last few years. His work gives a 

 general account of the history and the results of the observation of 

 glaciers, of the indubitable former extension of the ice-streams far 

 beyond their present limits on both sides of the Alps, and of the 

 distribution of the erratic blocks, as checked and confirmed by often 

 repeated visits to Switzerland, and further illustrated by journeys 

 in Iceland and Scandinavia. It is Waltershausen's object to base 

 the explanation of these facts, and of the great contrast to them 

 presented by the climate of the Tertiary period, upon the firm founda- 

 tion of weight and measurement, and to endeavour to prove that 

 they are consistent with the doctrine of the earth's heat as pro- 

 pounded by Fourier, thus standing in need of no hypotheses or 

 guesses, such as variable radiation of the sun, or hot and cold regions 

 in space, which are unsupported by any other class of observations. 



In order to estimate fairly the changes which may have taken 

 place, we must consider the several conditions on which the climate 

 of a given locahty is dependent, \iz. : — 



1. Its altitude above the sea-level. 



2. Its geographical latitude. 



3. The distribution of land- and sea-surface. 



* Quart. Journ. Geol. Soc. 1851, p. 60. 



t ■ ' Ueber die Klimate der Gegenwart und der Vorwelt,' von W. Sartorias 

 Ton Waltershausen. Haarlem, 1865. 4to, 388 pp. 



