Dkcemhkk 12, 1901] 



NA TURE 



125 



study of the animal life, and more particularly of the 

 water-life, of the Alpine lands. After briefly summarising 

 the evidence supplied by the Arctic-Alpine plants. Prof. 

 Zschokke refers to the former distribution of Arctic- 

 Alpine vertebrates in the low grounds at the foot of the 

 mountains, and gives a succinct account of the land- 

 shells, butterflies and beetles met with in the higher 

 Alps — many of which are true Arctic species. The major 

 portion of his treatise, however, is devoted to the origin 

 of the fauna of the Alpine lakes and streams. It would 

 appear that many of the forms now flourishing in the ice- 

 cold waters of the higher Alps hail from Arctic regions. 

 Even in the large lakes at the foot of the mountains a 

 glacial relict-fauna is encountered. Special reference is 

 made to the Salmonids of these lakes, which are now 

 cut off from the headquarters of their kind in the far 

 north. They doubtless immigrated from the north during 

 Glacial or early post-Glacial times, when such vast tracts 

 of middle Europe were under water, or traversed by 

 swollen rivers and great "canals," and when many of 

 the Alpine lakes were in free communication. It is note- 

 worthy that the Alps stopped migration further south, 

 and that the fish in question do not occur in the Italian 

 lakes. Eventually the limitation and interruption 

 of water-communication with the north led to the 

 trapping of the Salmonidte in the great lakes. And 

 now so long a time has elapsed since then that varieties 

 and even new species have been developed. The fish 

 can no longer migrate from lake to sea as their northern 

 cousins do ; but it is interesting to learn that at spawning 

 time they still gather in shoals, as if they were about to 

 set out on a journey. Perhaps this may be a remem- 

 brance of former conditions. Prof. Zschokke traces very 

 graphically the changes in the life of the Alpine lands 

 which ensued on the gradual disappearance of the 

 e.\treme glacial climate. In the ice-cold waters of the 

 higher Alps the Arctic types of life flourish at the surface, 

 just as they do in the lakes and streams of Greenland. 

 At the foot of the mountains, however, they are no longer 

 met with at the surface, but have descended to the cold 

 dark depths of the great lakes. As the mountains of 

 middle Europe became at the close of the Glacial period 

 "cities of refuge" to which the Arctic-Alpine flora 

 retreated, so in like manner they have afforded shelter 

 here and there to colonies of those Arctic forms of animal 

 life which are still so abundant in the tarns and streams 

 of the higher Alps, but have their headquarters in the 

 ice-cold waters of the Arctic regions. 



A Treatise on Elementary Statics for the Use of Schools 

 and Colleges. By W. J. Dobbs, M.A. Pp. xi -f 311. 

 (London : A. and C. Black, igot.) Price 7j. bd. 

 Thk author has already written an excellent book on 

 geometrical statics, and it has been his present object to 

 produce an elementary treatise which shall cover the well- 

 trodden ground of the parallelogram of forces, moments 

 and couples, centres of gravity, work, machines and fric- 

 tion, and at the same time shall develop the subject 

 simultaneously from its geometrical and analytical aspect. 

 It is sufficient to open the book almost anywhere to find 

 evidence of originality in the treatment. Thus in the 

 introduction the author does not leave his readers ignorant 

 of the e.\istence of non-rigid bodies (p. 7). Again, in 

 dealing with the parallelogram of forces, he wisely 

 eschews the fallacious so-called dynamical proof and 

 gives an ingenious modification of Uuchayla's proof, 

 together with an experimental verification in which three 

 strings stretched by spring balances, instead of being 

 knotted together, are attached to a triangular string 

 which forms a funicular triangle of the forces. This 

 plan has the advantage of also showing that three forces 

 in equilibrium meet at a point when produced. The 

 proof of the formula for the resultant of two parallel 

 .forces is based on the "funicular" method — a change 



NO. 1676, VOL. 65] 



that will be most refreshing to examiners. Whenever 

 a question is set in any examination, in which candidates 

 are asked to find the resultant or centre of a number 

 of parallel forces in such cases as that of a rod loaded 

 at different points, where the answer comes out in a Ime 

 by taking moments, pages and pages of work are usually 

 sent up with the old familiar figure and proof for the 

 resultant of tivo parallel forces: "(i) when the forces 

 are like ; (2) when the forces are unlike," and so on, 

 finishing up with the lame conclusion that the resultant 

 " may be found." The author's treatment of friction 

 strikes us as a very sensible innovation, the laws of friction 

 being based on a consideration of the angle of friction, 

 and the coefficient of friction being defined as the tangent 

 of this angle. There are a few points we do not alto- 

 gether care about ; for example, a crowbar problem on 

 p. 119, where "perfect roughness" exists between the 

 stone and the ground and between the crowbar and 

 ground, and " perfect smoothness " between the sharp 

 edge of the stone and the crowbar. In connection with 

 such a problem, too, the author might do well in 

 Chapter v. to say something about the direction of the 

 reaction when an edge of one body rests against, but 

 does not dig into, the surface of another. The book is 

 copiously supplied with examples. 



The Country Month by Month. By J. A. Owen and 

 G. S. Boulger. New edition. Pp. viii4-4g2. (London: 

 Duckworth and Co., 1902.) Price bs. net. 

 The best testimony to the appreciation of this work by 

 the reading public is that it has reached a second edition 

 — this being enlarged by the addition of notes written by 

 the late Lord Lilford. Mrs. Owen, who, as editor of the 

 delightful series of books bearing the signature " A Son 

 of the Marshes," has had a large experience of works 

 dealing with English country life, is responsible for the 

 portion of the present volume treating of the habits of 

 animals, while Prof. Boulger has written the botanical 

 portion. The partnership may be said to have turned 

 out in every way a success. 



As the authors say in their preface, popular works on 

 natural history absolutely swarm at the present day, but 

 there is no other which gives in such detail the changing 

 phases of animal and vegetable life throughout the twelve 

 months of the calendar. It is, in fact, an e.xpansion of 

 Gilbert White's " Naturalists' Calendar," written in an 

 interesting and attractive style and containing much 

 information which should be of use to the working 

 naturalist. In addition to the accounts of the habits of 

 animals, there are many observations scattered through 

 the book which, if not new, are at all events out of the 

 common. 



For instance, on p. in we find the remark that while 

 the French commonly name birds from their notes, the 

 English more generally call them after their appearance 

 or habits. The observation (p. 418) that night-herons 

 are increasing in number in Britain may perhaps be 

 connected with the depopulation of country districts of 

 which we hear so much nowadays. .And Lord Lilford's 

 note (p. 188) that frogs, small eels and young birds form 

 the favourite food of the otter strikes us as entirely 

 novel, since in Bell's " British Quadrupeds " we are told 

 that " the otter lives exclusively on fish, when it can 

 procure them." Nor do the authors confine their ob- 

 servations to wild animals, an interesting statement being 

 made on p. 468 that the Angora rabbit (or at all events 

 one individual thereof) sheds its coat entire. Misprints 

 and other errors appear few and far between, although 

 on p. 419 we notice "nob" standing in place of "knob." 

 We may add that we fail to see the advantage of putting 

 the date 1902 on a book which was in the reviewer's 

 hands by the middle of November 1901. 



To all lovers of the wild nature of our country this 

 work should prove, not only acceptable, but invaluable. 



R. L. 



