276 Reviews — Prof. Huxley's Presidential Address. 



be supposed to have been the state of the earth in those earlier ages 

 of which no records remain ; and the two sciences have much in 

 common, both make large calls upon the imagination, but the checks 

 furnished by evidence in the two cases differ so totally in degree, 

 that for clearness of thought it is far better to keep them apart, 

 and call them by different names, the one Geology, and the other 

 Cosmogony. 



And many an enthusiastic geologist fights shy of the latter on 

 account of the absence of any definite evidence on which to base 

 his reasonings ; this must have escaped Prof. Huxley when he would 

 have us believe that it is as easy to unravel the complexities of the 

 development of the earth as to trace out the development of the 

 fowl within the Q^^. We can examine as many eggs as we like, 

 during all stages of incubation, but when shall we be able to put 

 our theory of the earth's development to the test of observation ? 

 And this brings us to the real gist of the question, that our knowledge 

 is not yet sufficiently advanced to enable us to found a well grounded 

 Cosmogony. No better proof of this can be broiight forward than 

 a controversy on the chemistry of the primaeval earth, which took 

 place about a year and a half ago between two of the leading 

 chemical geologists of the day. While humble students were 

 anxiously looking to these great authorities for some land-marks to 

 guide them through the intricacies of the subject; some generally 

 received principle which all would agree to whatever might be the 

 difierences of opinion in details, they were more than ever be- 

 wildered by finding their two mentors strongly opposed to one 

 another on at least one important point. 



And now we must notice one or two weak points in Prof. Huxley's 

 defence, — masterly to a degree, when we reflect that geology is not 

 its author's special study. He has attempted to meet Sir W. Thom- 

 son's charge by shewing that the total thickness of the stratified 

 rocks might well have been deposited within the period to which 

 Sir W. Thomson wishes to tie down geologists. But the stratified 

 rocks do not represent the whole, probably nothing like the whole, 

 of geological time ; there are the unrepresented breaks to be taken 

 into account. But, as Prof. Huxley himself remarks. Sir William 

 Thomson's limits are so elastic that they might be found wide 

 enough to take in the whole, both of represented and unrepresented 

 geological time. It is with the greatest diffidence that we venture 

 to differ from Prof. Huxley on a point of biology, but we had 

 certainly never imagined that " the only reason we have for be- 

 lieving in the slow rate of change in living forms is the fact that they 

 persist through a series of deposits which geology informs us have 

 taken a long while to make." We had always imagined that our 

 own experience assured us that the rate of change in living beings 

 is now, and therefore probably always was, slow ; and that the 

 notion of the great length of geological time, which had previously 

 been arrived at on other grounds, was strengthened by a knowledge 

 of this fact. We have noticed these little matters, not because they 

 really weaken the case • for the geologist, but because they seem 



