June 30, 192 1] 



NATURE 



547 



One of the papers communicated to the Advisory- 

 Committee for Aeronautics deals with the analogy 

 •between the conduction of heat from a surface 

 .and the transfer of momentum in a viscous fluid 

 .flowing- over the surface. Lord Rayleigh shows 

 that the analogy, which holds so long as the 

 motion is laminar, breaks down when it becomes 

 turbulent. A letter to Prof. Xernst, dated 

 October, 191 1, is of rather special interest, 

 though there is nothing in the later pages of the 

 volume to indicate whether or not Lord Rayleigh 

 ■continued to hold the same opinion to the end. 

 He is discussing some of the difficulties which 

 .attend the kinetic theory of gases, and writes : — 



" Perhaps this failure might be invoked in sup- 

 port of the views of Planck and his school that 

 "the laws of dynamics (as hitherto understood) 

 •cannot be applied to the smallest parts of bodies. 

 But I must confess that I do not like this solu- 

 tion of the puzzle. Of course, I have nothing to 

 :say against following out the consequences of the 

 [quantum] theory of energy — a procedure which 

 has already, in the hands of able men, led to 

 some interesting conclusions. But I have a diffi- 

 •culty in accepting it as a picture of what actually 

 .takes place." 



A paper in the Philosophical Magazine for 1919 

 ■of somewhat greater length than the majority of 

 those in the present volum.e deals with the optical 

 •character of some brilliant animal colours. The 

 -question whether the colours displayed by various 

 Thirds, by butterflies, and by beetles are structure 

 -colours more or less like those of thin plates or 

 .-are due to surface or quasi-metallic reflection is 

 ■discussed, and the conclusion reached by Lord 

 Rayleigh is thus stated : — 



" The impression left on my mind is that the 

 phenomena cannot plausibly be explained as due to 

 surface colour, which in my experience is always 

 less saturated than the transmission colour, and 

 that, on the other hand, the interference theory 

 presents no particular difficulty unless it be that of 

 finding sufficient room within the thickness of the 

 •cuticle." 



In the paper a reference is made to the drawings 

 :and conclusions of the Hon. H. Onslow, some of 

 ■which have since been published. 



It is not necessary to add more, or to 

 attempt to give a full account of the con- 

 tents of the volume under review ; there 

 is interest to be found in every page, and 

 ■throughout it is marked by the characteristics 

 •of Lord Rayleigh 's writings. He is to be com- 

 memorated by a tablet and inscription in the 

 Abbey ; the six volumes of his collected works 

 form his true memorial, built by himself, to live so 

 long as there are students of physical science to 

 tread apd learn the truths which they contain. 

 NO. 2696, VOL. 107] 



The volume has been edited by his son, the pre- 

 sent Lord Rayleigh, with the help of Mr. W, F. 

 Sedgwick. It is published by the Cambridge 

 L'niversity Press in its usual admirable style, and 

 concludes with a classified table of contents of the 

 whole of the six volumes. The list, occupying some 

 forty pages, shows in a remarkable way the ex- 

 tent of ground covered by Lord Rayleigh 's con- 

 tributions to physical science. 



Studies of British Mammals. 



Habits and Characters of British Wild Animals. 

 By H. Mortimer Batten. Pp. 346. (London 

 and Edinburgh: W. and R. Chambers, Ltd., 

 1920.) 215. net. 



THERE are several trustworthy and readily 

 available books on British mammals, such 

 as Lydekker's and Sir H. H. Johnston's, not to 

 speak of the expensive volumes of Millais and 

 others, but there is a distinctiveness in Mr. 

 Mortimer Batten's studies which makes them 

 welcome. They have a broad basis of personal 

 observation, they give prominence to habits, and 

 they try to get at the character of the creatures. 

 The book is written in excellent style ; it smacks 

 of the open country, and it is packed with interest- 

 ing information without being overloaded. The 

 very artistic illustrations by Mr. \\'arwick 

 Reynolds appeal to us as revealing the tempera- 

 ment of the animals portrayed and also as pic- 

 tures, e.g. "tlie charming coloured frontispiece 

 of roe-deer jumping up at rowan berries. 



Mr. Mortimer Batten deals with red deer, roe- 

 deer, fox, weasel, stoat, otter, pine-marten, 

 badger, polecat, brown hare, mountain hare, 

 rabbit, hedgehog, squirrel, brown rat, water-vole, 

 and wild cat. Without rigidly adhering to any 

 scheme, he discusses range, feeding habits, 

 breeding, struggle for existence, interrelations, 

 general characteristics, size, weight, and last, not 

 least, the disposition or character. We wish that, 

 when he was at it, he had completed his survey of 

 British mammals so that his excellent book might 

 have been a comprehensive unity. A second edi- 

 tion should remedy this. We do not mean that 

 there need be any treatment of the Orkney vole and 

 that sort of thing, but we miss the little gentle- 

 man in the velvet coat; we should like to have 

 seen the book representative of all the short list 

 of British mammals. W'e must protest, of 

 course, against the usage which calls this a book 

 on British wild animals. 



We have found Mr. Mortimer Batten's studies 

 full of interest, and we have a lively appreciation 

 of their originality and independence. Some- 

 times, we confess, his theoretical interpretations 



