6o4 



NA TURE 



[April 27, 1S99 



I cannot refrain from drawing attention to the fine ideal 

 of the scientific man's action in regard to the fisheries 

 which our author holds up to us. 1 quote from p. 223 : 



" A close observer of nature, he weaves no theories, 

 and is not incautious in deduction. The welfare of the 

 fisheries as a whole is his aim, and the influences which 

 act on those engaged financially in them, or have political 

 or other connections with them, are unknown to him." 



Prof. M'Intosh's friends may be permitted to add that 

 he himself realises that ideal more nearly than any one 

 else we know in the field. 



The book is charmingly illustrated with views of the 

 marine laboratory, the harbour, the boats, and some 

 characteristic features of fishing life in the celebrated old 

 Scottish university town of .St. .Andrews, which the fame 

 and long-continued labours of Mcintosh have done so 

 much to render a " Mecca " to the young marine 

 zoologist. \V. A. Herdm.\n. 



OUR BOOK SHELF. 

 The Leptdoptera of the British Islands. A Descripti','e 

 Account of the Families, Genera, and Species Indi- 

 genous to Great Britain and Ireland, their Preparatory 

 States, Habits, and Localities. By Charles G. Barrett, 

 F.E.S.,one of the Editors of the Entomologist's Monthly 

 Magazine. Vol. V. Heterocera : Noctu«. Pp. 381. 

 (London : Lovell Reeve and Co., Ltd.) 



In the present volume, I\Ir. Barrett discusses in species 

 of British Noctuic, in the same elaborate manner as in 

 the volumes which we have previously noticed. He has 

 long been recognised as one of our best living authorities 

 on the British Lepidoptera, and his book will remain o{ 

 great and permanent value as a record of the state of this 

 branch of our fauna as it exists at the end of the present 

 century. Among the most interesting moths here noticed 

 are those which are attached to the Fens, several of which 

 are now very much scarcer than formerly in England, 

 though some species (such as Tapinostola concolor, Guen.), 

 which were supposed to have become extinct, have now- 

 been rediscovered in other localities ; while several Fen 

 species, quite unknown during the palmy days of the 

 Fens, have lately been discovered there. \Ve have heard 

 it suggested that this may be due to fresh localities in the 

 Fens having been made accessible by drainage ; but in 

 the case of Calaiitia hrevilinea, Fenn, Mr. Barrett re- 

 marks : " It seems to furnish all the evidence which it 

 would be possible to obtain, in order to suggest the actual 

 genesis, or introduction of a total novelty, to the world's 

 fauna." It appears that the exact locality where the 

 insect now occurs was well worked in 1857, without its 

 being discovered ; but in 1864 the first specimen was 

 taken, and no more till 1871, when a few specimens were 

 taken, after which, it has become Ijoth commoner and 

 more widely spread in the Fens, and a single specimen 

 has been taken in Belgium. The remarks on the habits 

 of various moths, especially, perhaps, their behaviour 

 at sugar, &c. (under the notice of Taeniociimpa gothica), 

 will also be read with interest. The well-known cannibal 

 habits of the \ar\:io{ Cosmiatrapezina are also remarked 

 on. It should be observed that this work is issued in two 

 editions — one with, and the other without, plates. 



W. F. K. 



An Introduction to the Mathematical Theory of Attrac- 

 tion. By Francis A. Tarleton, Sc.D., LL.D. Pp. 

 xii + 290. (London : Longmans, Green, and Co., 1899.) 

 Till-: author tells us that his object is to make the 

 acquisition of a competent knowledge of the theory of 

 attraction as easy as possible for the student. With this 



NO. 1539. VOL. 59I 



view he has given, in addition to the theorems on attrac- 

 tions and potential to be found in most of the te.\t- 

 books, an account of the theory ot electrostatics and some 

 outlines of the theory of magnetism. He has attended 

 almost exclusively to the mathematical view of his 

 subject. Possibly the students for whom he writes will 

 have formed sound physical conceptions before they begin 

 to read his book ; in that case they will probably find in 

 it what they want in the way of mathematical theory. 



To indicate the scope of the book, we may observe that 

 it contains such things as the determination of the 

 attraction of an ellipsoid by direct integration, Laplace's 

 equation in elliptic coordinates, the distribution of elec- 

 tricity on a freely charged spherical bowl, and Kirchhoflf's 

 theory of the distribution on two spheres. .-X. student for 

 whom these things are not too difficult could appreciate T 

 many things that are omitted, such as the potential of a 

 magnetised body of finite size, Laplace's equation in 

 orthogonal curvilinear coordinates and the logarithmic 

 potential in three dimensions. The author has done well 

 in refraining from barren discussions of artificial laws of 

 force differing from that found in nature. 



The plan followed, viz. that of treating gravitational 

 attraction and electrostatic and magnetic forces together, 

 has the disadvantages that the standard case of attraction 

 is repulsion and that special units have to be used in 

 treating gravitation ; it has the advantage that it tends 

 to break down the system of water-tight compartments in 

 which students always store their knowledge. A number 

 of results that might be more simply ol)tained by indirect 

 methods are obtained by direct integration. The potential ' 

 is introduced comparatively late, the definition even being I 

 postponed to the fourth chapter. One excellent feature I 

 of the book is that two-dimensional problems and three- I 

 dimensional problems are treated separately and side by I 

 side. T 



The author's mathematical methods are the traditional 

 ones of British text-books, except that here and there he 

 presents investigations by Mr. Purser. But surely it is 

 time that writers of books, even on applied mathematics, 

 took some account of modern developments of analysis. 

 If an exhaustive discussion of the existence theorem 

 would be out of place, it would yet seem not unreasonable 

 to expect the banishment of such banalities as "con- 

 secutive points" and "infinitely small quantities,' the 

 avoidance of meaningless equations between divergent 

 series and divergent integrals, the presentation of a proof 

 that the convergent integrals which represent the com- 

 ponents of attraction at a point within an attracting mass 

 are the differential coefficients of the con\ergent integral 

 which represents the potential at such a point, a little 

 care in extending Gauss's theorem concerning the surface 

 integral of normal force from a single particle to a distri- 

 bution of density, some discussion of the discontinuity of 

 the second <litf"ei-ential coefficients of the potential at the 

 boundary of an attracting body. Why write a new book 

 which follows the old ones in leaving undone the things 

 that ought to be clone, and doing the things that ought 

 not to be done .' 



The book contains several interesting collections of 

 examples. These should prove useful to teachers as well 

 as to students. A. E. H. L. 



Outlines of the Earth's History; a Popular Study in 

 Physiography. By Nathaniel Southgate Shaler. 

 Pp. viii + 4iS. (London: William Heinemann, 1S98.) 

 In these outlines Prof. Shaler has felt the necessity of 

 selecting certain features of the history of the earth for 

 comparatively full treatment in order to supply a more 

 helpful aid to a true knowledge of the earth than is 

 afforded by the "ordinary text-books." .-Vt first sight 

 the selection appears inadequate and arbitrarily pro- 

 portioned. The seven chapters devoted to the concrete 

 subject (after thirtv pages of introductory matter) are 

 entitled "The Stellar Realm,. "The Earth," "The 



