January 4, 1894] 



NATURE 



221 



the one aspect of the problem which he alone touches upon. 

 He urge* that my paper contains a fallacy and a misrepresenta- 

 tion. The alleged fallacy is, that because the lakes in question 

 are found in glaciated and not in otherwise similar non- 

 glaciated regions, "therefore the rock-basins in which the lakes 

 lie were excavated by glaciers." But this is not my argument, 

 and therefore not my fallacy, What I say is — "there must be 

 iomc causal connection between glaciation and these special types 

 of lakes. What the connection is we shall enquire later on." 

 That there is a "causal connection " Mr. Oldham asserts as 

 strongly as I do myself, though it is a different, and as I have 

 endeavoured to show, an untenable one. 



This brings us to the alleged misrepresentation, which is, that 

 I have imputed to the opponents of the ice-erosion theory, the 

 view that the earth movements which, as they allege, produced 

 the lakes, occurred in the period just before the ice-age came on. 

 Mr. Oldham says, this is an unreasonable and unfounded limi- 

 tation, since the movements in question probably occurred 

 throughout the glacial period itself, I quite admit the validity 

 of this criticism, and that I should have added, "or during the 

 glacial period itself," to, "immediately before" it. I cer- 

 tainly had this probability in my mind, and the reason I did not 

 express it was twofold. In the first place, all the advocates of 

 the earth-movement theory appeared to assume, either directly 

 or implicitly, the preglacial origin of the lakes; and secondly, 

 this assumption gave them the strongest argument against my 

 views, and I therefore gave them the benefit of it. Mr. Oldham 

 appears to have overlooked this. Yet it is clear that the shorter 

 you make the time since the formation of lake basins by earth- 

 movements the more difficulty there is in explaining the total 

 absence of valley-lakes from all the non-glaciated mountain 

 regions of the world, since there is less time for them to have 

 been all silted up. When arguing this point I said — in the pas- 

 sage evidently referred to by Mr. Oldham — "The only way to 

 get over the difficulty is to suppose that earth-movements of 

 this nature occurred only at that one period, just before the 

 ice-age came on, and the lakes produced by them in all other 

 regions have since been filled up." I thus gave my opponents 

 the benefit of an extreme supposition which was all against 

 myself ; while the more reasonable view, that earth-movements 

 are just as likely to have occurred during and since the glacial 

 epoch as before it, renders my argument from the geographical 

 distribution of lakes much stronger, since it is impossible to 

 believe that, if lake basins as large and as deep as those of 

 •Geneva, Maggiore, Como, Constance, and Garda, were formed 

 ■in non-glaciated regions as recently as the middle or latter part 

 of the glacial epoch, a considerable number of them would not 

 'be still in existence. 



Of course, if it can be shown that filled up lake-basins exist 

 in tropical and subtropical regions, corresponding in number, po- 

 sition, size, and depth, with those of glaciated areas, the argument 

 from geographical distribution will break down. At present 

 I am not aware of any evidence that such is the case. But 

 even if it were so, there remains the singular correlation 

 between the size and depth of lake basins and the known size 

 of the glaciers that occupied these valleys ; together with the 

 surface and bottom contours of the lakes themselves, so strongly 

 opposed to their production by any form of valley-subsidence or 

 €arth-movements. 



A friend has pointed out an unsound argument in my article 

 on the above subject in the Fortnightly Revitio, and I therefore 

 ask to be allowed to state what it is, and thus avoid its being 

 possibly made the subject of discussion in the pages of Nature. 

 As a proof of the very great erosive power of ice I have adduced 

 Dr. Helland's estimate of the quantity of Scandinavian debris 

 in Northern Europe. But it is evident that this only proves the 

 great carrying power of the ice, since the rock and gravel would 

 be mostly of sub-aerial origin. It, however, indicates a very 

 long period during which the ice-sheet was at work, while the 

 clayey element in it would be due to erosion. The larger part 

 of this, however, would certainly have been carried away into 

 the North Sea during the passage of the ice-sheet across the 

 Baltic. The enormous quantity of boulder-clay in North 

 America, which I have also referred to, is a better indication of 

 true ice-erosion. Alfred R. Wallace. 



The question you have allowed me to raise is too important 

 and far reaching to justify its dissipation upon personal issues. 

 It cannot be thought unreasonable that those geologists who 

 propound transcendental theories should justify the mechanical 



NO. 1262, VOL. 49] 



postulates on which they claim to base them. This is all I 

 have asked. 



Dr. Wallace asks me to explain what will happen when suffi- 

 cient pressure is applied to ice not only to crush it, but to in- 

 duce retfelation. I have already explained in my work, that 

 the notion of fracture and regelation taking place in glaciers is 

 at issue with the details of their differential motion as tested by 

 experiment. There is no evidence that ice which on pressure 

 being applied to it has ample room to move, will undergo 

 regelation at all. The pressure when crushing ensues will be 

 dissipated in the direction of least resistance, and most probably 

 upwards. This emphasise'-; Mr. Deeley's statement, and he 

 wrote as a champion of Dr. Wallace, that " fracture and 

 regelation have little to do with the question." 



Dr. Wallace then returns to his charge against me that I have 

 in some way committed myself in my work to a position incon- 

 sistent with the one I am now maintaining. I can assure him 

 that if he has read this meaning into my words, it was not what 

 they were meant to convey. In giving the history of the "Glacial 

 Nightmare," I entered largely into the views of Charpentier, and 

 in so far as he championed glaciers as against ice sheets I agree 

 with him. I have said that his views " are for the most part 

 soitnd and tmanswerable, since they finally established for the 

 Alpine country and for Switzerland the fact that glaciers ivere 

 formerly much more extensive" &c. Beyond this I could 

 not go, since my work was written to prove the unscientific 

 character of the extravagant conclusions of the later glacialists, 

 including Charpentier himself after he became a follower of 

 Agassiz. Apart from this, however, what your readers I am 

 sure would welcome would bean argumenturn ad rem, and not 

 one ad hominem. 



In demanding that the advocates of the glacial theory in its 

 extravagant form should justify their premises and postulates, I 

 must not be understood to decline to meet the geological case 

 against the glacial excavation of lobes. I have met it at great 

 length already in my recent work, but not so ably and not so 

 thoroughly as Mr. Spencer met it in his elaborate and crushing 

 examination of the critical case of the North American lakes, 

 which I commend most heartily to the study of enthusiastic 

 champions of omnipotent ice. 



The geological question, however, is necessarily contingent 

 upon the mechanical question, and no amount of ingenuity 

 will in the long run enable those who invoke ice as the author 

 of all kinds of geological work to evade the duty of proving its 

 capacity to do that work, and notably to explain how it can 

 travel over hundreds of miles of level country, or suddenly 

 begin to excavate deep and extensive lake basins after it has 

 been moving gently over its own bed of soft materials for many 

 miles, or, indeed, how it can excavate on level ground at all. 

 The first step is to show that ice can convey thrust in a way 

 to compass these ends ; the second one is to show whence this 

 thrust is to be derived. Your readers who are committed to 

 no theories unsupported by facts, will not quarrel with the 

 reasonable demand that these first steps should be surmounted 

 before we advance any further. Those who like to traverse 

 cloud-land on the wings of fancy may be otherwise satisfied. 

 To them I would only say that the result cannot be science ; it 

 must remain nothing more than poetry. 



Henry H. Howorth. 



30 Collingham Place, Earls Court, December 30, 1893. 



Hindoo Dwarfs. 



In your issue of November 9, 1893, is a notice of some 

 photographs, by Colonel A. T. Eraser, of two dwarfs, taken in 

 the Kurnool district of the Madras Presidency, near Bellary. 

 Erom the account given of these dwarfs — the hereditary nature 

 of the deformity, its limitation to the males of the family, the 

 inability to walk, the normal bodily growth up to six years of 

 age^it seems possible, if not probable, that the family is 

 afiflicted with the disease known as pseudo-hypertrophic 

 paralysis (Duchenne's paralysis). Any physician could settle 

 the question immediately on seeing one of the subjects in 

 question ; and very probably a study of the photographs would 

 be sufficient. I have had cases of this disease in my wards at 

 the General Hospital, sent from Bellary. Perhaps Colonel 

 Eraser would kindly send me a copy of one of the photographs, 

 or show them to another medical officer, and tell us his 

 opinion. 



Madras, December 2, 1893. 



A. E. Grant. 



