114 MR. A. W. WATERS ON A CHANGE IN 



recurring glacial periods. A few have been discovered to 

 order ; but it may safely be predicted that some, at any rate, 

 will not stand examination. For, instead o£ there being 

 any indication of a gradual decrease of temperature as the 

 palseontological record most distinctly shows for the recent 

 glacial period, we are, for the earlier ones, required to 

 believe that where we have found a coral atoll growing, 

 indicating a tropical temperature, a glacial period of greater 

 intensity than that of the ice-age was brought about, and 

 the glaciers transported their debris where the corals just 

 grew. These glaciers were soon tii'cd of their anomalous 

 position and retired, when immediately there was a fauna in- 

 dicating a temperature warmer than at present, without any 

 palseontological record being left to indicate there had ever 

 been a colder period ; so that the phenomena are explained 

 by getting from great difficulties into much greater ones. 



Mr. CrolFs theories may account for somewhat warmer 

 periods in the Arctic region ; but the question remains so 

 unsatisfactory that, while accepting the explanation as an 

 influencing cause, there are many who would like a further 

 one. Sir Henry James*, and Sir John Lubbock f^ and Mr. 

 John Evans J have suggested a change in the position of 

 the axis, upon different grounds ; but the astronomers have 

 said that no change in the geographical position of the axis 

 can have taken place. And this, as far as I can understand 

 it, has rested upon the figure of rotation of the earth, as the 

 equatorial bulge of 26 miles is just the amount which cal- 

 culation, as worked out first by Newton, showed that the 

 earth ought to have, and which the astronomers said that 

 the earth must have taken before it solidified to its present 

 condition, the argument being based upon the earth being 

 now so rigid that it could not take this form of a semifluid 



* ' Athenajum,' i860, Aug. 25. t Quart. Journ. Geol. Soc. 1846. 



I Proc. Eoy. Soc. 1866. 



