52 



NATURE 



[November i6, 189; 



bit of dead furze stem. As he was bending over it, the 

 supposed withered stem moved slightly, and gave him 

 the impression that he was looking at the back of a large 

 viper that had half buried itself in the furze. A still 

 closer scrutiny showed that the semblance of a crooked 

 piece of furze was two fern-owls about three days old. 



We have read the book from cover to cover, and have 

 been interested throughout. The author has looked to 

 animate nature for his facts ; hence his work possesses 

 the sterling ring which every student of science delights 

 to hear. 



Pitt Press Euclid, V.-VI. By H. M. Taylor, M.A. 



(Cambridge: Univ. Press, 1893.) 

 We h?ve previously had occasion to refer to the earlier 

 issues of this series of books on the elements of Euclidian 

 geometry. The present publication is quite up to the 

 standard of the former ones, and contains some impor- 

 tant variations from the usual mode of treatment. In 

 dealing with the fifth Book, Mr. Taylor rejects altogether 

 the use of figures, since, as he rightly says, the book is 

 not essentially geometrical. With a general knowledge 

 of proportion as derived from treatises on algebra, a 

 student is sufficiently equipped to follow its applications 

 in Book vi. The numbering of the propositions is 

 somewhat altered owing to the omission of some of the 

 propositions in the Greek te.xt. With regard to Book vi. 

 Mr. Taylor has made some modifications in the treat- 

 ment of similar figures, and many theorems are more 

 briefly proved by adopting the definition of similar 

 polygons there enumerated. The additional theorems 

 which are inserted have been arranged in series — 

 one, for instance, giving the student a sketch of the 

 theory of transversals, harmonic and anharmonic ranges 

 and pencils, leading up to Pascal's theorem ; another of 

 nine propositions, concluding with Gergonne's neat solu- 

 tion of the problem to describe a circle to touch three 

 given circles. The method of inversion, Casey's exten- 

 sion of Ptolemy's theorem, properties of coaxial circles, 

 and some porismatic problems follow next in order, the 

 book concluding with a capital set of exercises and an 

 index for the first six books. 



The Out -door World, or Young Collector's Handbook. 



Bv W. Furneaux, F.R.G.S. (London : Longmans, 



1893-) 

 A GREAT deal of information useful to the young col- 

 lector, for whom Mr. Furneaux has prepared this hand- 

 book, is to be found in its four hundred pages. There 

 are sixteen coloured plates, some of which are excellent 

 and none bad, and more than five hundred illustrations 

 in the text. Those of birds are somewhat unequal ; 

 some indication of relative size would have been helpful. 

 The linnet and the cuckoo are placed side by side, and 

 the former is apparently the larger of the two, while on 

 the opposite page the great tit is considerably bigger 

 than the lark, and rivals the cuckoo in apparent propor- 

 tions. If the length of the bird had been given in 

 brackets after the name under each figure, it would have 

 prevented misapprehension. We have dipped here and 

 there into the letterpress, and found the information 

 accurate and clearly put. 



IVorked Examples in Co-ordinate Geometry. (Univ. 

 Corn Coll. Tutorial Series.) By William Briggs and 

 G. H. Bryan. (London : W. B. Clive and Co., 1S93.) 



The examples which are here brought together are 

 intended to serve as a graduated course on the right line 

 and circle, forming thus a useful companion to the book 

 on Co ordinate Geometry already published by the 

 same authors. The work line is specially designed for 

 the private student, and this is why the problems have 

 been dealt with in such detail, everv step in their solution 



NO. 1255, VOL. 49] 



being clearly explained. The examination papers may 

 fairly be taken as good test papers, for the questions 

 seem to have been carefully selected, and the more im- 

 portant ones on book work are not lacking. For those 

 teaching themselves this subject by working out the 

 problems given, a good insight should be obtained, while 

 the references to the author's work on co-ordinate 

 geometry, above referred to, will be found very useful 

 to those possessing that book. 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by /lis correspondents. Neitlier can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part ^"Naturk. 

 No notice is taken of anonymous communications. \ 



Sir Henry H. Howorth on "Geology in Nubibus.'' 



Having given my views on glacial geology in the current 

 issue of the Fortnightly Review, to be followed by one dealing 

 at some length with the ice-origin of lake-basins, I should not 

 have thought any reply to Sir Henry Howorth's "Appeal" 

 necessary except for the consideration that my articles may not 

 be seen by many readers of Nature. And first, I would 

 remark, that the mental attitude which Sir H. Howorth imputes 

 to extreme glacialists I have myself been unable to detect in 

 their writings. In fact, I was under the impression that the 

 "scoffing " and "jeering" was chiefly from the other side ; but 

 it seems I was mistaken, and I must apologise for my ignorance. 

 Those who read my articles will see that I make no appeal to 

 "transcendental ice," but judge of its powers and properties by 

 its admitted effects. Sir H. Howorth says .that " ice is known 

 to crash under moderate pressure," implying that a glacier 

 a mile or perhaps half a mile thick is impossible. But will he 

 or anyone else tell us what happens to the ice after it is 

 crushed, and the pressure that crushed it is continued and 

 slowly increased ? Will it not suffer re-gelation and become 

 denser ice; and if by sudden increase of pressure it is again 

 crushed, will it not by still further pressure again suffer re-gela- 

 tion ? He stops at the first " crushing," as if that were the end 

 of all things so far as a glacier is concerned. All this, however, 

 is beside the question from my point of view. The work of ice 

 on the rocks is as clear as that of palaeolithic man on the flints ; 

 all the difficulties that may be suggested as to how he lived, or 

 how he shaped the flints do not in the slightest degree affect our 

 conclusion that the palaeolithic flint implements are the work of 

 7nan ; and there is equally clear evidence that ice did march a 

 hundred miles, mostly uphill, from the head of Lake Geneva 

 to Soleure, whatever transcendental qualities it must have 

 possessed to do so. 



As to "perhaps the largest and most remarkable collection of 

 rock-basins in the world" — the largest being of 50 acres and 

 the deepest 30 feet deep — I must really decline to occupy your 

 space in showing how simply these may have been produced by 

 ordinary denuding agencies, or in denying that any glacialist, 

 even of " the most extreme and aggressive school," would claim 

 them as proofs of glaciation. As regards the question of Tas- 

 manian glaciation, my last communication to Nature (Nov. 2) 

 seems to me to render any further observations unnecessary. No 

 doubt the conclusions of the various writers will be fully har- 

 monised by a more complete study of the whole region. 



The last point touched on by Sir \\. Howorth — whether the 

 advocates of the ice-origin of certain groups of lakes are 

 " extravagant" in their views, following the methods of Aristotle 

 rather than those of Bacon, and founding their be iefs on 

 "purely hypothetical properties of matter and forces of nature" 

 — I will leave to the judgment of those who do me the honour 

 of reading my forthcoming article in the Fortnightly Review. 



Alfred R, Wallace. 



The Erosion of Rock-Basins. 



Mr. T. D. LaTouche's letter (page 39) is very interesting 

 as a more than usually independent contribution (for the 

 reason given therein) to the interesting question of glacial 



