534 



NATURE 



{April lo, 1890 



The book is modelled upon the " Fodder-grasses of 

 India," published not long ago, in two volumes, by Mr. 

 Duthie, the director of the botanical department of 

 Northern India, and to Mr. Duthie the author is indebted 

 for the botanical determination of the species. He gives 

 the native name of each plant, and a short account of 

 the extent and manner in which it is used, and as most 

 of them have a wide dispersion, this will be found 

 useful in other dry sub-tropical regions. Out of thirty- 

 seven species, the two great tropical tribes are represented, 

 PanicecB by twelve species, and AndropogonecB by ten, and 

 only three species fall under Festncccc, the tribe to which 

 most of our North European pasture grasses belong. The 

 plates are lithographed from photographs, and do not 

 contain any dissections. Plate III., called Panicum 

 Criisgalli, is clearly not that species, but a .form of P. 

 colonu7n, another variety of which is figured on Plate II. 

 Mr. Coldstream also has got entirely wrong with his 

 two species of Cyperiis, figured on p. 38. The left-hand 

 figure, called Cypertts species, is evidently Cyperus Ivia, 

 Linn., a common weed throughout India in rice-fields. 

 The left-hand figure, labelled Cyperus Tria, is not in 

 flower. There is no such plant known to botany ; Tria 

 is doubtless a mistake for 7via. The figure is quite 

 unrecognizable, but from the native name appended, 

 " Motha," it is most likely Cyperus rotundus. 



J. G. B. 



Eletnentary Dynamics of Particles and Solids. By W. M. 

 Hicks, M.A., F.R.S. (London : Macmillan and Co., 

 1890.) 



In this excellent treatise, extending over nearly 400 pages, 

 the author introduces to the student the principles of 

 dynamics. Although the book is issued under the latter 

 title, it will be found to differ considerably in its treat- 

 ment from the majoi-ity of text-books on the same subject. 

 For instance, the two subjects of statics and kinetics have 

 been considered together, the former being regarded as a 

 special case of the latter. Again, the discussion of force 

 is reserved until an attempt has been made to give an 

 idea of mass and its measurement ; thus a preliminary 

 study of momentum finds an early place. 



Although the mathematical acquirements of the stu- 

 dent of these pages may be limited to a knowledge of the 

 elements of algebra and geometry, he will be able to 

 readily follow the methods adopted in establishing the 

 various results. This the author has kept in view through- 

 out his work, except in a few cases where, in the hope of 

 rendering it useful to a larger circle of readers, he has 

 had recourse to the trigonometrical ratios for examples 

 which he has worked out. 



The volume is divided into three portions (i) recti- 

 linear motion of a particle ; (2) forces in one plane ; 

 (3) plane motion of a rigid body. 



One cannot read the first few chapters without observing 

 the care taken by the writer in trying to impart to the 

 student a correct and precise idea of the fundamental 

 units. That this is a very important matter all will agree 

 who have had any experience in teaching or testing 

 students. The most deplorable state of ignorance some- 

 times exhibited by them, in giving their results in all 

 manner of absurd units, should encourage both teacher 

 and author to make a special effort when dealing with the 

 question of units, fundamental or otherwise. 



As the subject of statics is included, an opportunity has 

 been taken of introducing the method of drawing stress 

 diagrams for loaded framework ; this will be valuable to 

 engineering students. 



Notwithstanding that the writer has forbidden himself 

 the use of the integral calculus, he has been able to 

 establish (in some cases very neatly) many useful results 

 in the two chapters on centre of gravity and moment of 

 inertia, which should be read with care. 



Neatness in method characterizes the book throughout 



and an unusually large number of examples will be found 

 at the end of each chapter. 



The work is based on a series of lectures delivered by 

 the author at the Firth College, Sheffield, and many 

 details for which time can generally be found at the 

 lecture table have in this case found their way into the 

 book. 



These will help to lessen the individual difficulties ot 

 students, and their views of the subject will be enlarged 

 thereby. There can be little doubt that the text-book 

 will have a deservedly favourable reception. 



G. A. B. 



Catalogue of the Fossil Reptilia and Amphibia in the 

 British Museum {Natural History). Part III., con-' 

 taining the Order Chelonia. By Richard Lydekke'r,. 

 B.A., F.G.S., &c. (London: Printed by Order of the; 

 Trustees, 1889.) 



Mr. Lydekker is to be congratulated on having added' 

 one more to the valuable series of catalogues of ther 

 pala^ontological collections in the British Museum which 

 he has compiled during the last {^w years. Like his 

 previous catalogues, the present work indicates an enor-' 

 mous amount of careful and accurate work, which, how- 

 ever, is of such a special kind that it cannot easily be 

 summarized in a short review. 



The extreme difficulty of correlating the fossil forms, 

 of Chelonia with the recent, on account of the frag- 

 mentary character of many of the remains, is indicated 

 by the fact that, out of the 52 genera and 131 species 

 or varieties described, the author has only been able to 

 place with certainty 18 genera and 10 species amongst 

 existing forms. The classification adopted is to a great, 

 extent that followed by Mr. Boulenger in his catalogue 

 of recent Chelonians. The work is illustrated by 55 

 woodcuts, and abundant references to the bibliography 

 of the group are given. It must be added, as stated in 

 the preface, that " the collection which forms the subject 

 of this Catalogue is particularly rich in Chelonians from 

 the Purbeck Beds of Swanage, the Cretaceous of England 

 and Holland, the Eocene Tertiaries of Warwick, Sheppey, 

 Hampshire, the Isle of Wight, and the older Pliocene of 

 the Siwaliks of India." The last-named beds have yielded 

 the largest tortoise known {Testudo [Colossochelys'] atlas 

 of Falconer), the carapace of which measures about si.\ 

 feet in length. 



LETTERS TO THE EDITOR. 



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

 pressed by his correspondents ■ Neither can he undertake 

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

 manuscripts intended for this or any other part cf Nature, 

 No notice is taken of anonymous communications. "[ 



Systems of " Russian Transliteratio-n." 



As one who takes an interest in the Russian tongue, quite apart 

 from the value of the scientific papers published in that language, 

 I may perhaps be allowed to express my regret that the author 

 of " A Uniform System of Russian Transliteration," publishecl 

 in your issue of February 27 (p. 397), has departed in almost 

 every point where it is possible to do so from the system of 

 transliteration which has been in use in England for about a 

 century, and which has, moreover, the advantage of being almost 

 identical with that current in France. 



A system of transhteration may be founded on one of two 

 bases — namely, the empirical, in which little or no account is 

 taken of the sound of the letters in the foreign language, and the 

 rational ; in the latter the letters of the foreign language are, 

 where possible, represented by letters or groups of letters which 

 have as nearly as may be the same sound as the original. For 

 instance, B in Russian would be represented by B in English, 

 these two having the same sound. It seems to me that the latter 

 is the most convenient .system, and the one which ought to be 



