JrxK 4, 1896] 



NA TURE 



forerunner, the result being that the book provides a 

 jjood >;eneral preparatory course, which will give students 

 of medicine a broad and satisfactory view of the principles 

 of physics, and will equip thoin with very serviceable 

 l<nowledi;e. Intended primarily to meet the new regu- 

 lations of the General Medical Council (which make 

 physics a part of the extended course of professional 

 study), the book contains numerous examples of the 

 application of physical principles to medical science, re- 

 lating both to instruments and muscular actions. But 

 though medical students will find special interest in some 

 of the examples used to illustrate the subjects described, 

 the information given can readily be understood by all 

 who read with studious mind. Therefore we commend Dr. 

 Danieirs volume to teachers of physics generally, believing 

 that they will find it worthy of adoption. The contents in- 

 clude chapters on units of measurement, motion of bodies, 

 friction, matter, sound, heat, ether-waves, and electricity. 

 All these subjects are treated as thoroughly as is possible 

 in a book of this character. 



Physics cannot be learned : it must be experienced. 

 Dr. Daniell recognises this, and points out that his work 

 " is not designed to supersede, but rather to clear the 

 ground for practical teaching and demonstration." It is 

 to be hoped that this practical work will some day form 

 a part of the professional curriculum. 



P/ivsiui/ Ciii/s. By Magnus Maclean, M.A., D.Sc, 

 F.R.S.E. Pp.147. (London: Biggs and Co., 1896.) 



It can safely lie said that this book will find its way into 

 every laboratoiy where physical facts are investigated. 

 The tables of results brought together in the volume will 

 be most useful for reference ; and as they represent deter- 

 minations made by foremost workers, trust can be put 

 in them. .Additional value is given to the tables by tlie 

 fact that references are made in most cases to the books 

 and papers from which the data have been obtained. 



Two-thirds of the book are de\oted to the discussion 

 of physical units and the relations between them, the 

 remaining third being taken up with the tables already 

 mentioned. Students of ph\sics will obtain from the 

 text clear and sound knowledge of their units of measure- 

 ment, and to more advanced investigators the book will 

 prove a veritable vade-mecum. 



Elements of the Theory of Functions. By Dr. H. Durege. 

 Translated by George Egbert Fischer and Isaac J. 

 Schwatt. Pp. 28S. (Philadelphia, 1896.) 



The late Prof. Durdge's treatise, in this English transla- 

 tion, will be a welcome addition to the works on this sub- 

 ject by Forsyth and Harkness and Morley. Durege 

 has a genial method of exposition, as all who know 

 his other book on Elliptic Functions will testify. The 

 numerous definitions and novel ideas in the "Theory of 

 Functions '' are made clear by well-chosen illustrations 

 and diagrams. There is no reference to the date of the 

 first edition, but we believe it goes back some thirty 

 years : so that Durege could claim to be a pioneer in the 

 presentation of this subject to the general reader, Weier- 

 strass's ideas being inaccessible to all except his own 

 imiversity pupils. G. 



Charles Darwin and his Theory. By M. .\. .•\ntono\ ich. 

 Pp- 353, with a portrait. (Russian.) (St. Petersburg, 

 1896.) 



This is a very good summary of the chief works of 

 Darwin, in which his scientific \ icws are intimately inter- 

 woven with personal details of his life, in so far as they 

 are known from Francis Darwin's " Life and Letters," 

 and partly from Krause's " Charles Darwin," the whole 

 being written with a deep admiration of both Darwin's 

 personal qualities and his philosophy. 



NO. 1388, VOL. 54] 



LETTERS TO THE EDITOR. 



[?'//<? Editor lioes not IwlJ liimself responsible for opinions ex- 

 pressel by his correspondents. Neither can he undertake 

 to return^ or to correspond with the writers of rejecte i 

 manuscripts intended for this or any other part of Natiire. 

 No notice is taken of anonymous coininunicalions.] 



A Query concerning the Origin of Atolls. 



Havi.n'g recently visited and studied in some detail the coral 

 mass of the Bermuda Islands, I have been impressed by one thing 

 more than by anything else, namely, the fact so long known 

 that the islands owe their present elevation almost exclusively 

 to the action of the wind. The hills, which often rise to a 

 height of 200-250 feet above the sea, from near their base to 

 their summit, are made of blown coral sand, now consolidated 

 into a more or less compact rock. 



A recent subsidence has carried most of the islands below the 

 sea level, leaving only the more elevated southern part above, 

 because this had been built higher than the rest by the strong 

 southern winds. This subsidence has been so recent that the 

 heavy south waves are still battering at the clift'; and the debris 

 thus obtained, added to that furnished by the abundant coral 

 growth of the reef which lies immediately off shore, has not 

 yet been able to build extensive beaches. Here and there we 

 find beaches, usually small ones, and from these the sand is 

 even now marching inland and adding to the height of the land, 

 illustrating the process by which the islands have been reared to 

 their present height. Nevertheless, although in a few places 

 the importance of the wind action is still illustrated, it is prac- 

 tically at an end, and that because of a recent subsidence of 

 certainly 50 feet and probably less than too feet. 



On the basis of these facts I wish to propound a query which 

 has arisen in my mind, but which I would not assume to answer 

 on the basis of a study of only one coral island. Granting an 

 atoll ring formed in the mid-ocean in the way which the theory 

 supported by Dr. Murray and others demands, would we not of 

 necessity have first a ring of reef or beach rock, then of coral 

 sand which with age continued to rise in elevation until the 

 Bermuda stage was reached? For various reasons a luxuriant 

 vegetation would not at first serve to check this. A constant 

 supply of sand is furnished by the life which skirts the shore, 

 the waves are present to drive it on the shore, and the wind to 

 heap it up. 



Given this tendency and islands either standing at a uniform 

 level, or being elevated, there should, it would seem, he all 

 gradations between the atoll ring and the insular mass of wind- 

 blown sand not unlike the Bermudas. If, however, the older 

 theory advocated by Darwin and by Dana were correct, there 

 would not need to be such a condition, for subsidence would 

 counteract the action of waves and winds, and the ring con- 

 dition of the low atoll could easily be the type condition. 



Cornell University, Ithaca, N. V. Ralph S. Takr. 



"The Primary Factors of Organic Evolution." 

 In a review of Prof. Cope's " Primary Factors of Organic 

 Evolution" (Nature, vol. liii^ p. 553), Dr. Alfred R. W.dl.ace 

 denounces its " extraordinary statements," its " misstatement.s," 

 and its "absurd arguments," and finds it refreshing to turn to 

 the original ideas and acute reasoning of another book. The 

 fact that the first book is by an opponent and the second by a 

 follower of the reviewer, perhaps accounts for, though it does not 

 justify, opinions that depart widely from what will be the 

 judgment of the most competent. A work of unusual origin- 

 ality such as Prof Cope's, is apt to contain much that is open to 

 criticism ; but it is no small matter to have brought together, as 

 he has done, the evidence in favour of finding in the environ- 

 ment, in the movements of animals and in consciousness, the 

 efficient factors of organic evolution. The present writer finds 

 the arguments inconclusive, Iiut he does not understand how 

 any one can read the book without admiring the intimate know- 

 ledge of facts and the great powers of generalisation which it 

 discloses. Dr. Wallace states that it is "absolutely untrue" 

 that " the variation which has resulted in evolution has not been 

 multifarious or promiscuous, but in definite directions," yet the 

 evidence oftered for this proposition — due perhaps more to Prof. 

 Cope than to any other — has within the past few months proved 

 convincing even to Prof. Weismann. Prof. Cope's book and 

 his work should be adequately described and seriously criticised ; 

 but Dr. Wallace has done neither. J. McKeen Cattei.l. 

 Columbia University, New York, May 9. 



