172 



NATURE 



[June 24, 1897 



since it deals exclusively with that debated point, the 

 action of two elements of current on one another. 



So long as Maxwell's theories of the mutual induction 

 of closed circuits are taken as the starting-point, a certain 

 indeterminativeness must inevitably arise in the en 

 deavour to isolate the effects of separate portions of the 

 circuits. It is with the various rival hypotheses required 

 to complete the solution of the problem that the present 

 investigation deals. In the first section we have an 

 account of Ampere's hypothesis and the laws of force 

 resulting from it. The next section deals with the most 

 general law of force, based on the law of the inverse 

 square ; this is followed by a section devoted to Max- 

 well's investigations, and finally Dr. Kerntler propounds 

 a new law of force which, he claims, is free from the 

 objections raised by him against Ampere's, Neumann's, 

 Weber's, and other formula;. This law is merely obtained 

 by assigning certain values to the arbitrary constants 

 which occur in the expressions for the force-components, 

 and which satisfy the relations found by Stefan. The 

 subsequent applications of the proposed law to finite 

 portions of conductors form an interesting collection of 

 problems. 



An important feature is that the author divides the 

 various hypothetical laws into two categories — those 

 which are applicable to determine the action between 

 closed circuits only, and those which give correct results 

 when used to find the action of a closed circuit on an 

 element of current. 



In former times, when the doctrine of action at a 

 distance held the field, such an investigation as the 

 present would, doubtless, have attracted many sup- 

 porters, between whom and the advocates of Ampere's 

 and other laws a spirited controversy might have arisen. 

 At present we have become so accustomed to regarding 

 the seat of electro-magnetic action as residing in the 

 dielectric, that it is difficult to regard any investigation 

 of direction action and reaction between two elements 

 of current as being of more than purely academical 

 interest. Still, the fact that many of our text-books base 

 their introductory treatment, both of electrostatics and of 

 magnetism, on the theory of action at a distance renders 

 it desirable that interest should be resuscitated in these 

 attempted solutions of the corresponding problem for 

 electric currents; and for this, if for no other reason, the 

 present endeavour to establish a new formula cannot fail 

 to be worthy of the attention of physicists. G. H. B. 



Catalogue of Tertiary Mollusca. Part i. The Austral- 

 asian Tertiary Mollusca. By George F. Harris. Pp. 

 xxvi 4- 407. Eight plates. (London : Printed by 

 order of the Trustees of the British Museum, 1897.) 

 Catalogue of the Fossil Cephalopoda. Part iii. The 

 Bactritidas and part of the sub-order Ammonoidea. 

 By Dr. Arthur H. Foord and George Charles Crick. 

 Pp. xxxiii -I- 303. Illustrated. (London : Printed by 

 order of the Trustees of the British Museum, 1897.) 

 The present work by Mr. Harris commences a new cata- 

 logue. This first part is devoted to descriptions and 

 figures of the shells of Australasia (exclusive of Cephalo- 

 poda), and will be followed, in due course, by other 

 geographical series in the collection. The larger part of 

 the Mollusca and Bryozoa, and the whole of the Brachio- 

 poda, Annelida, Arthropoda, Echinoderma, and Coelentera, 

 still remain to be recorded, as well as the greater portion 

 of the fossil plants. When complete the catalogue will 

 include at least thirty volumes, and will then contain no 

 more than a brief account of these extensive collections 

 in the Natural History branch of the British Museum. 



The classes of Australasian Tertiary Mollusca described 

 by Mr. Harris in the volume under consideration include 

 the Gasteropoda, the Scaphopoda, and the Lamelli- 

 branchiata, and the author rightly points out that their 

 study cannot fail to shed rnuch light on certain questions 



NO. 1443, VOL. 56] 



relating to phylogeny, and to assist the zoologist in 

 tracing the origin of many of the principal groups of these 

 divisions of the Mollusca. 



The eight plates, drawn by Miss G. M. Woodward, 

 which accompany the text, are of the usual high order of 

 excellence^ one associates with the publications of the 

 Trustees o'f the British Museum. 



The volume dealing with the Cephalopoda is mainly 

 the work of Mr. Crick, though Dr. Foord, notwith- 

 standing his removal to Dublin, has rendered all the 

 assistance possible, in order to carry the work through 

 the press. As Dr. Woodward points out in his preface, 

 this addition to the catalogue will prove of extreme im- 

 portance to all those who desire to study the phylogeny 

 of this group, for we are here presented with conclusive 

 evidence that the Goniatites almost imperceptibly pass 

 into the Ammonites. The figures, of which there are 

 one hundred and forty-five, prepared, with few exceptions, 

 by Miss Woodward, assist very much in making the 

 text clear. 



The Story of the Aline, as illustrated by the Great 

 Comstock Lode of Nevada. By Charles Howard 

 Shinn. Pp. x -t- 272. (London : Gay and Bird, 1897.) 

 We learn from the editor's preface that this volume is 

 one of a series intended to explain how the Western 

 States of America were explored, how cities sprang up 

 in desert wastes or among mountains difficult of access, 

 and how gradually these States have become the home 

 of a thriving population. The part played by the miner 

 in the wonderfully rapid development of the Great West 

 is dealt with by Mr. Shinn in a masterly manner. 



Taking the Comstock Lode as a typical example, he 

 draws a vivid picture of the early prospecting and sub- 

 sequent working. The pathetic story of the first dis- 

 coverers, the brothers Grosh, who both perished before 

 they could reap the fruits of their skill and energy, is 

 probably unknown to most English readers ; soon they 

 were followed by hardy but ignorant prospectors, who 

 began by working the gold which they chanced to find in 

 the earth thrown up by a gopher, and threw away as value- 

 less the very rich silver ore which accompanied it. An 

 assay of the " blue stuff," carried by a farmer to a distant 

 town, revealed the true wealth of the marvellous vein ; 

 but difficulties of all kinds beset the miner in his 

 endeavours to work it. How they were overcome by 

 pluck, perseverance and science, is told in Mr. Shinn's 

 pages ; these should be read by every student of mining, 

 for he may glean from them much valuable information, 

 which is usually placed before him in a less tempting 

 fashion in his dry technical manuals. Numerous illus- 

 trations add value to the text. The view of the Belcher 

 Mine shows very clearly how the huge underground 

 excavations are supported by "square sets," and might 

 well be copied as a diagram for teaching purposes. The 

 picture of hydraulic mining is excellent, and decidedly 

 better than some similar illustrations which appear in 

 text-books on mining. It is a pity there is no index. 



C. L. N. F. 



First Stage Sound, Light and Heat. By John Don, 

 M.A., B.Sc. Pp. 307. (London : W. B. Clive, Univer- 

 sity Correspondence College Press.) 

 The syllabus . of the Science and Art Department's 

 elementary examination in Sound, Light, and Heat, is the 

 framework upon which this book has been constructed. 

 The facts and phenomena belonging to the branches of 

 physical science named in the title of the book are clearly 

 described, and with due attention to experiment. 

 Teachers of Departmental classes will be attracted to the 

 book by its conciseness, by the summary at the end of 

 each chapter, and by the large number of exercises and 

 problems to be found in its pages. 



