188 



THE GEOLOGIST. 



l)oration of the views laid down in the paper which had been 

 read ? 



Dr. Black w^as quite familiar with Agassiz's notions on that 

 head, but he could not see that they warranted the specula- 

 tions of Mr. Harkness as to the alterations in the tempera- 

 ture of the ocean. For his part, he thought they could not 

 speak with any confidence on the question, till they had as- 

 certained at wdiat point the specific gravity of sea water was 

 greatest. 



Professor Wallace was of opinion that the density of sea 

 water was governed by the same law as that of fresh water. 

 The mean point of specific gravity v/as different ; but its de- 

 crease, as the temperature rose or fell, would, no doubt, be 

 after the same rate. He thought the hypothesis now pro- 

 pounded would, in connection with the glacial theory of Pro- 

 fessor Agassiz, account for most of those fluctuations in 

 the surface of the ocean which have taken place at various 

 periods. 



The chairman said there was one point on which he would 

 like to have some explanation. They w^ere aware, that, from 

 recent experiments, it had been ascertained that the tempe- 

 rature of the earth increased in proportion to the depth pe- 

 netrated. At a depth of two miles, it had been calculated 

 that the temperature would be equal to that of boiling water. 

 Now, were there no means of determining w^hether land and 

 sea were alike in this respect ? Another question was with 

 regard to the condensation of water at great depths. They 

 all knew that w^ater was compressible to a considerable extent; 

 and it might therefore be taken for granted, that in the 

 deepest parts of the ocean the low-er strata would thus be 

 much more dense than those near the surface. After a few 

 remarks from other members, the thanks of tlie society w^ere 

 given to Mr. Harkness for his contribution, and to the chair- 

 man 'j after w- hich the meeting terminated. 



