294 



NA TURE 



[January 7, 19C9 



the percentage frequency in each class being stated. It 

 is suggested that the numerous composite types may be 

 explained by the action of inheritance from three primary 

 types, in accordance with the lines laid down by Mendel. 



I.' Aero MC-canique is the title of a new monthly paper 

 published at Brussels (Rue royale 214). No. 5 before us 

 contains, among other articles, one by Captain de Vos 

 on the much-vexed question of the flapping wing of the 

 bird, and extracts from current journals, patents, and so 

 forth. 



The Revue generale des Sciences reproduces in its issue 

 for December 15, 1908, the address given by Prof. H. 

 Poincar^ to the Mathematical Congress at Rome on 

 "The Future of Mathematics." In the introductory part, 

 which precedes the discussion of special regions of mathe- 

 matical study, the author di.scusses the aims and objects 

 of the pure mathematician, the reasons for his insistence 

 on rigour and elegance in his proofs, and his relationship 

 to the engineer. 



The equilibrium of a flexible string forms the subject 

 of a paper in the Transactions of the American Mathe- 

 matical Society, ix., 4, by Prof. E. B. Wilson. It is pointed 

 out that the ordinary solutions for the cases of a rectilinear 

 field, whether parallel or central, fail to lead to interest- 

 ing problems when the string has a free end, but the 

 paper shows that there is a large class of cases, which 

 may be explicitly integrated by quadratures, where this 

 objection does not apply. 



A HISTORY of the origin of the theory of the Eother is 

 contributed by Dr. L^on Bloch to the Revue g^iidrale des 

 Sciences, xix., 22. It deals very largely with the theories 

 of Newton and Hooke. The author shows that as new 

 physical discoveries have taken place, the theory of the 

 aether has undergone a continual process of evolution, and 

 he predicts that the same will take place in the future. 

 A rigorous dynamical theory of this medium which does 

 not admit of modification in the light of new discovery 

 cannot be regarded as final. 



Prof. E. B. Wilson, writing in the Bulletin of the 

 American Mathematical Society (December, iqo8), dis- 

 cusses the analogy between statistical mechanics and 

 hydrodynamics, an analogy primarily based on the identity 

 between the Eulcrian equation of continuity and the corre- 

 sponding relation between the differential coefficients of 

 momenta and coordinates. According to this view, it is 

 obvious that the detcrminantal relation of the kinetic 

 theory represents the Lagrangian equation of continuity. 

 The purpose of the paper is to examine whether the equa- 

 tions of motion, and in particular those of irrotational 

 motion, have any analogues on the dynamical side. The 

 search does not appear to lead to any results of great 

 importance so far. 



Messrs. Burroughs Wellcome and Co. have sent us 

 a copy of Wellcome 's " Photographic Exposure Record and 

 Diary " for the year 1909, and an examination of it shows 

 that in this handy little book the owner possesses a store 

 of practical information in the smallest compass for one 

 shilling. In this year's issue a further attempt has been 

 made, and we think with very successful results, to con- 

 dense statements to the minimum number of words, and 

 this has allowed extra matter on other subjects to be 

 inserted. A new feature of the article on exposure is the 

 insertion of two tables dealing with the relative speed 

 of bromide papers and lantern plates. These should be 

 found very useful, because if the user knows the correct 

 NO. 2045, VOL. 79] 



exposure for any one of these, that for any other can 

 be determined at a glance. Other items here tabulated 

 are the various exposures of interiors, copying and 

 enlarging, moving objects, Szc, and an excellent list of 

 plate speeds, brought up to date, is added. Perhaps the 

 main feature of this pocket-book is the exposure calculator 

 at the end, which by this time has become of such general 

 use. In this issue the series of illustrations of character- 

 istic subjects is printed on a separate card and placed in 

 the pocket of the book, the use of the calculator being 

 thus facilitated. 



We have received from Messrs. John J. Griffin and 

 Sons, Ltd., of Kingsway, London, a conveniently arranged 

 and profusely illustrated catalogue of models for teaching 

 machine construction and drawing, pattern making and 

 foundry practice, building construction, and mining opera- 

 tions. Teachers of these subjects should find the catalogue 

 of great" assistance and very suggestive in developing the 

 practical side of the instruction they give. 



Whitaker's " rcerage. Baronetage, Knightage, anrt 

 Companionage for the Year iqog " is now available. The 

 character of this useful work of reference is too well 

 known to mal^e any extended description of its contents 

 necessary. A new feature of the present issue is an 

 addition to the introduction in the form of an " Official 

 Glossary," which provides useful information to persons 

 who are not experts in the various departments with 

 which the volume deals. The work includes an extended 

 list of the Royal Family, the peerage with tilled issue, 

 dowager ladies, baronets, knights and companions, home 

 and colonial bishops, and an index to country seats. 



Messrs. .ARCiiin.M.n Constable and Co., Ltd., have 

 published a revised and abridged edition of " The Life 

 .Story of .Sir Charles Tilston Bright, Civil Engineer; with 

 which is Incorporated the .Story of the Atlantic Cable and 

 the First Telegraph to India and the Colonies." The 

 present volume has been prepared by Mr. Charles Bright 

 alone, who, in the task of writing the original work, was 

 assisted by his uncle, Mr. E. B. Bright. The book was 

 reviewed at length, soon after its original appearance, in 

 Nature for October 26, 1899 (vol. Ix., p. 613). This 

 abridgment appears appropriately, since 1908 was the 

 fiftieth anniversary of the Atlantic cable, and the short 

 account of the w-ork of so exceptionally able, energetic, 

 and enthusiastic a man as the late .Sir Charles Bright 

 should be wflconie to many readers. The price of the 

 new issue is 125. 6rf. net. 



OUR ASTRONOMICAL COLUMN. 

 Astronomical Occurrences in January ; — 

 Jan. 7. I3h. 2ini. to i6h. 41m. Transit of Jupiter's Satellite 



III. (Ganymede^. 



10. igh. Tiipi'er in conjunction with the Moon. (Jupiter 



4''ri'S.). 



11. I4h. 23m. to I5h. 32m. Moon occults v Virginia 



(mag. 4-2). 

 22. gh 41m. tn i3h. 32ni. Transit uf Jupiter's Satellite 



IV. (Callisto). 



25. oh. 12m. Minimum of A'gol (S Perspil. 



25. 5h. 59m. to 7h. 2m. Moon occults 30 P s:ium (mag. 



47)- 

 ,, 7h. 44111. to Sh. 37m. Moon occults 33 Piscium 

 (mag. 4-6). 



26. 6h. im. Minimum of Algol (fl Persei). 



,, l6h. Mercury at greatest elongation, 18° 25' E. 

 30. 2oh. Mercury in conjunction with Uranus. (Mercury 

 0° 21' N.). 



