Oct. 27, 1887J 



NA TURE 



603 



by the doctrine of motion without any reference to the 

 propositions of Euclid which precede it." In all, the 

 author applies his method to forty-one examples, the 

 treatment of which will present no difficulty to the student. 

 If the method is not thoroughly new, it is true, and 

 offers an interesting field for investigation. 



Many of our readers have no doubt made an acquaint- 

 ance with Mr. Proctor's pages already, as they originally 

 appeared in Knowledge. In his preface the author states 

 as his experience : — " I could find no interest in the differ- 

 ential calculus, till, after wading through 200 pages of 

 matter having no apparent use (and for the most part 

 really useless), I found the calculus available for the 

 ready solution of problems in maxima and minima. This 

 little work has been planned with direct reference to my 

 own experience at school and college." In 114 small 

 pages Mr. Proctor very luminously, we think, unfolds the 

 raison d'etre of the calculus, and by easy yet sure 

 stages carries his reader over a good deal of ground, 

 sufficient for a large class of students. The proofs are 

 clear, and apparently quite level to the comprehension of 

 a student who has a solid, but not necessarily extended, 

 knowledge of elementary mathematics. It is a good 

 introduction to a great subject, and is calculated to entice 

 readers to go on further. Several well-chosen problems 

 are fully worked out, and there are a few others for the 

 student to tackle himself. There are not many errata, 

 but there are slips on pp. 52, 73, 95, 109, and quite a 

 crop on p. 1 10. 



" First Steps in Geometry " is a reprint ; it certainly 

 well deserves an extended circulation, especially amongst 

 intelligent mechanics and others who cannot command 

 the assistance of teachers, for they will appreciate the 

 way in which the writer goes about his task. His 

 " method of showing why such and such paths should 

 be tried, even though some may have to be given up, in 

 searching for the solution of problems," is likely to be 

 very suggestive to the thoughtful student. There is a 

 vast quantity of good work in the little book, and the way 

 in which the second book of Euclid is treated ought to 

 find a place in our school text-books. 



OUR BOOK SHELF. 



The Photographer' s Indispensable Hand-book. Compiled 

 by W. b. Welford. Edited by H. Sturmey. (London : 

 Iliffe and Son, 1887.) 



This book is practically a complete cyclopjedia on the 

 subject of photographic apparatus, materials, and pro- 

 cesses, &c. Those who intend purchasing articles 

 pertaining to photography cannot do better than look 

 through these pages, where they will find a great amount 

 of useful knowledge and information massed together in 

 one volume. 



It would be impossible to describe the various kinds of 

 cameras and processes, &c., which are dealt with here, but 

 we need only add that they are profusely illustrated and 

 well classified. 



One of the latest novelties in the way of secret cameras 

 is shown in " the watch," which, when closed, is exactly 

 like an ordinary watch. It is opened by a spring, when 

 a series of about half-a-dozen tubes shoot into position. 



A great assortment of the different make and kinds of 

 drop-shutters which at the present time are so largely 

 used for instantaneous work is added. 



Ueber GetniWisbexvegungen. Von Dr. G. Lange. Autorisirte 

 Uebersetzung von Dr. H. Kurella. (Leipzig: Theodor 

 Thomas, 1887.) 



The original essay of which this is a German translation 

 is in Danish, and was published in 1885. The author is 

 a Professor of Pathological Anatomy in Copenhagen, and 

 is well known both as a practical physician and as a man 

 of science. He does not pretend to deal fully with the 

 complicated and difficult questions connected with the 

 expression of the emotions. He examines, however, with 

 much care the physical accompaniments of sorrow, joy, 

 terror, and anger ; and he offers important suggestions as to 

 the point of view from which the entire subject can be most 

 successfully studied. That emotions are not, in any sense 

 which can be recognized by science, the causes of the 

 physical phenomena associated with them is a proposi- 

 tion on which he lays great stress ; and in support of his 

 opinion he presents a number of arguments which deserve 

 the attention of all who are interested in psycho-physio- 

 logical studies. The German translation is very clear, 

 and will no doubt find readers in England as well as in 

 Germany. 



Three Lectures on the Forms of Nasal Obstruction in 

 relation to Throat and Ear Disease. By Greville 

 Macdonald, M.D. (London: A. P. Watt, 1887.) 



These lectures were originally delivered at the Throat 

 Hospital, Golden Square. They do not constitute a text- 

 book, but the author has embodied in them the results of 

 much inquiry as to various forms of nasal obstruction. 

 The diseases of which he treats are all of common occur- 

 rence, yet some of them have hitherto been but inade- 

 quately described, and Dr. Macdonald holds that their 

 pathology is often totally misunderstood. His exposition, 

 therefore, should be of service both to the student and to 

 the general practitioner. 



LETTERS TO THE EDITOR. 



{The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he under- 

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

 rejected manuscripts. No notice is taken of anonymous 

 communications. 



[The Editor urgently requests correspondents to keep their 

 letters as short as possible. The pressure on his space 

 is so great that it is impossible otherwise to insure the 

 appearance even of communications containing interesting 

 and novel facts. ^ 



"The Scenery of Scotland." 



The review by Mr. A. \l. Green, of Geikie's " Scenery of 

 Scotland," published in your paper of October 13 (p. 553), does 

 not, I think, show any accurate appreciation of the disputable 

 points in that work. The fundamental proposition ascribed to 

 Hutton is "that the surface features of the land are, in the 

 main, due to the carving and sculpturing action of denudation." 

 Mr. Green does not seem to be aware that the truth of this 

 doctrine may entirely depend on the definition of the words 

 "surface features," and of the subsequent words "in the 

 main." 



As there is probably no actual " surface " existing in the world 

 which has not been weathered more or less (except the very 

 freshest lavas), the doctrine of Hutton, when so stated, is not 

 only true, but it is a truism. Indeed the words " in the main " 

 might be omitted ; because it would be substantially true that all 

 " surface features " in this literal sense are due entirely to denuda- 

 tion. 



But if the words "surface features" be understood not 

 literally, as confined to any mere visible surface, but as applying 

 to all forms and shapes underlying mere surfaces, then the 

 doctrine is open to great debate, and the truth of it turns entirely 

 on the breadth of interpretation given to the words " in the 

 main.' 



Living as I do in the Highlands, I maintain that the forms of 



