38o NATURAL SCIENCE. Nov.. 



the present one. The chapter on the molecular theory of glacial 

 motion is cancelled. This is peculiarly gratifying to me. For years 

 I have been trying to champion Forbes' theory of glacial motion, and 

 have written a great deal on the subject. I have always deemed it 

 to be the pivot of any possible glacial theory. When Mr. Geikie 

 brought out his previous edition he brushed Forbes' theory aside as 

 impossible, and devoted many pages to a theory invented by CroU, 

 which has been the amazement and amusement of many of us, 

 namely, the molecular theory of ice motion. This is now thrown 

 over without a word. Forbes' theory is completely accepted, and 

 one of the old masters justified. So far, so good. And yet Croll was 

 right. He wanted ice to do some wonderful things which a viscous 

 body will not do. Forbes' ice — the ice we all know and can 

 experiment upon — was no use to him. He had, therefore, to invent 

 a special ice of his own. His scholar, Mr. Geikie, wants to do CroU's 

 work with Forbes' tool?. Assuredly, to change my metaphor, the 

 old wine cannot exist long in the new bottles. Let us proceed, 

 however. The chapters on cosmical changes of climate are now 

 condensed and remitted to a short concluding chapter, with an 

 ominous change in its heading — it is now entitled " Cause of 

 the Glacial Period " — and to foot-notes full of ambiguous surrender. 

 We are even told that if Mr. CroU's views happen to turn out to be 

 wrong, still Mr. Geikie's geological conclusions will remain. All this is 

 very curious — curious rather as a study of human nature than of science. 

 Let me next refer to one or two critical instances of Mr. Geikie's 

 method of ignoring his opponents and critics. He devotes two 

 considerable chapters to the vexed question of the origin of rock 

 basins and mountain lakes. In this he repeats the kind of arguments 

 which Ramsay long ago published, and he largely quotes from 

 Mr. Wallace, who is a distinguished zoologist, but whose reputation 

 in geology has still to be made. Will it be believed that not a word 

 of any kind is said about the arguments on the other side, urged by the 

 Duke of Argyll and Mr. Bonney, both ex-presidents of the Geological 

 Society of London, nor of those of Mr. Spencer, who is in the very first 

 rank of American geologists, which arguments have simply pulverised 

 the whole theory of glacier erosion of such lakes ? It is literally one 

 of the most impertinent incidents in all my experience of literature, 

 that Mr. Bonney's elaborate memoirs on this subject, directly aimed 

 at Mr. Wallace and Mr. Geikie himself, should be completely ignored 

 — Mr. Bonney, who has probably spent as many months in exploring 

 the handiwork of ice in Switzerland and Norway as Mr. Geikie has 

 spent days, and who has inductively analysed this particular problem 

 with great sagacity and experience on the spot, where the lessons can 

 be really learnt, and not by a process of deduction from impossible 

 mechanical data. 



In regard to the astronomical theories of an ice age as urged 

 by Croll and Sir Robert Ball, we are treated to a rechauffe of 

 old arguments which have been riddled through and through, not 

 merely by geolo^^ists, but by mathematicians and astronomers, like 

 Mr. G. Darwin, Mr. Meach, in America, and, lastly, by Mr. Culvewell, 

 who at the British Association at Oxford assuredly gave a final 

 quietus to the v/hole subject in an analysis of its conditions, whose 

 force was acknowledged by Sir R. Ball himself. Not a word is said 

 of all this, but the ingenuous youth of Scotland is led to believe that 

 the position is still intact, and that there is still something to be said 

 for astronomical cycles causing climatic revolutions in the earth. 



