466 Notices respecting New Boohs. 



geological climate, arid the principal controversies which have arisen 

 in connection with the theory, have appeared in the pages of this 

 Magazine, and may be presumed to be familiar to its readers. His 

 own contributions to the controversy during the last ten years Dr. 

 Croll has now gathered together, and presented to the public in the 

 volume which forms the occasion of this notice. The work is 

 largely controversial in tone, more taken up with maintaining the 

 position of the theory as enunciated in ' Climate and Time ' than 

 in broadening its foundations by new views, or even in resolving 

 difficulties and clearing the logical path along which Dr. Croll leads 

 his adherents. Dr. Croll is not prepared to accept any of the modi- 

 fications of his theory which have been proposed ; still less is he 

 inclined to coincide in the arguments which would be subversive of 

 his position. In the preface to this volume he intimates that he has 

 now spoken his last word in defence of his theory. " There are 

 many of the topics discussed," he says, " which I could have wished 

 to consider more at length ; but advancing years and declining 

 health constrain me to husband my remaining energies for work in 

 a wholly different field of inquiry — work which has never lost for 

 me its fascination, but which has been laid aside for upwards of a 

 quarter of a century." Such a decided intimation of withdrawal 

 from a controversy in which he has so long been the principal figure 

 surely forms a fitting occasion for an acknowledgment of the vast 

 and varied services Dr. Croll has rendered to an obscure branch of 

 science, of the amount of intellectual activity and industry to which 

 his writings have given rise, of the large measure of light he has 

 thrown on what appeared to be the most complex and puzzling 

 phenomenon which meets the student at the very gateway of geo- 

 logical investigation, and to the stimulating and suggestive models 

 he has afforded for dealing with the ravelled skein of geological 

 history in many of its departments. 



Dr. Croll's theory, all opposition notwithstanding, holds the field. 

 Many have taken objection to the entire fabric, and still more have 

 been opposed to various propositions by which the theory is sup- 

 ported ; but no opponent has been able to suggest that most 

 powerful of all arguments — a counter-theory. It is almost a me- 

 lancholy sight to see the learned President of the British Association 

 falling back upon the antiquated Lyellian doctrine. Whatever 

 may satisfy the conditions of the problem of Grlacial periods, it is 

 now well known that Sir Charles Lyell's theory of polar continents 

 and tropical oceans will not supply the key; but Principal Dawson 

 can discover, or has at his service, no other. But although no 

 effective counter-theory has been started, even as a stalking-horse, 

 against the Croll doctrine, it is not to be concluded that the con- 

 troversy is at an end, and that henceforth the theory that periodic 

 changes of climate are primarily caused by Eccentricity is to be 

 accepted as an artiele of faith in the schools of geological and phy- 

 sical orthodoxy. It would indeed be a misfortune were the con- 

 troversy, which has gone on so briskly for about twenty-five years, 

 to be allowed to subside. Authorities who are prepared to accept 



