;64 



NA rURE 



[Feuruary i8, 1892 



In the condensed edition the cartouches of Egyptian 

 kings which stood at the head of the chapters in the 

 second Enghsh edition have been placed at the beginning 

 of the book, and Miss Brodrick has added five pages of 

 matter on the Der el-Bahari mummies. 



We have long hoped that Dr. Brugsch would issue a 

 new edition of his " Aegypten unter den Pharaonen," 

 revising his facts in some places, and correcting his 

 statements in others, and also adding the new facts 

 relating to the periods between the VI I.-XIth and XI 1 1.- 

 XVIIth Dynasties, which have recently come to light; 

 failing this, which is much to be desired, we hoped that 

 one of his pupils would do the work under his guidance. 

 That, however, the English translation made by Seymour 

 and Smith, mutilated and robbed of its notes, and of the 

 additions of the author, should be issued as a popular 

 text-book of Egyptian history under Brugsch's name is 

 a fact which we deplore. 



OUR BOOK SHELF. 



The Story of the Hills : a Popular Accou7it of Mountains, 

 and how they were made. By the Rev. H. N. Hutchin- 

 son, B. A., F.G.S. (London: Seeley and Co., 1892.) 

 This is a pleasant, chatty book, all the more welcome 

 because wholly unpretentious ; not too deep for " human 

 nature's daily food " when roaming among the hills of 

 which it treats. It will be read with pleasure and profit 

 by the tourist, who likes to know just enough about the 

 sundry points of interest connected with the scene of his 

 wanderings to make the enjoyment of his outing intelli- 

 gent, but who is not haunted by a feverish anxiety to be 

 for ever, in season and out of season, improving his 

 mind. Many who would shrink from a formal scientific 

 treatise with horror or disgust will find themselves able 

 to enjoy this book, and through its channel scraps of use- 

 ful knowledge may insinuate themselves into their minds 

 which would never have found their way there by any 

 other road. 



Part I. is multifarious, and touches on a vast variety 

 of matters more or less connected with mountains, and 

 principally of human interest — mountain races, mountain | 

 legends, the uses of mountains to mankind, mountain I 

 storms, avalanches, and the plants and animals of moun- \ 

 tains. Scientific explanations of facts and phenomena 

 are interspersed : the severe critic may detect a little 

 vagueness and looseness here and there in these, but no 

 very serious lapse. Well-chosen quotations from Ruskin 

 and other authors give brilliancy to the narrative. There i 

 are landscape views reproduced from photographs, which ! 

 have all the excellences and the artistic failings of this { 

 class of illustration. 



Part II. is mainly taken up with a geological history of 1 

 mountains. Here all the main geological truths that : 

 bear on the subject are expounded clearly, and with 

 great fullness of detail. In fact, an epitome is given of a 

 large number of the leading doctrines of geology, which 

 will suffice for the needs of many a general reader. A 

 separate chapter is devoted to volcanic mountains and 

 volcanic activity. We may note that the three stages in 

 the life of a volcano mentioned on p. 266 are not such as 

 are usually defined by geologists. A. H. G. 



The Optics of PhotograpJiy and Photographic Lenses. 



By J. Traill Taylor. (London : Whittaker and Co., 



1892.) 

 Although photography is so widely practised at the 

 present day, it is surprising how little is known by 



NO. 1 164, VOL. 45] 



I amateurs about the principles that underlie the con- 

 I struction of photographic lenses. 



I The present work will serve as an excellent guide to 

 j those who wish to gain this information, and should be 

 I found to be of great practical use. The author has dealt 

 I with the subject in a very popular manner, and although 

 j the mathematics is reduced to a minimum, he has made 

 : his meaning very clear throughout. 



In the first few chapters the nature and properties of 

 light are discussed, together with explanations of photo- 

 j graphic definition, single and achromatic lenses, cause of 

 I the inverted image, spherical aberration, nature and func- 

 tion of diaphragms, nature and cure of distortion, optical 

 centres of single and combination lenses, &c. Chap- 

 ters xi. to XV. treat solely of lenses, including accounts 

 of the non-distorting, wide-angle, portrait, landscape^ 

 copying, and universal lenses. As there are thirty-nine 

 chapters in all, we may mention that of those remaining 

 there are many on subjects which may be of special 

 interest to individual readers. Thus we have a chapter 

 dealing with photo-telescopic lenses, a short one on the 

 grinding of lenses, and another on enlarging and pro- 

 jecting in relation to lantern optics. 



It will be seen that the author has dealt with a 

 wide range of subjects in which the lens makes its ap- 

 pearance, and the reader will find that the explanations 

 are lucid, while the illustrations bring out the points 

 which they are intended to show with equal clearness. 



W. 



The Evolution of Life j or, Causes of Change in Animal 

 Forms. A Study in Biology. By Hubbard Winslow 

 Mitchell, M.D. (New York and London: G. P. 

 Putnam's Sons, 1891.) 



Dr. Mitchell says in the preface to this book that he 

 has accomplished in it " all that can be reasonably ex- 

 pected from a medical man deeply immersed in the duties 

 of his profession." What most people expect from medical 

 men in this position is that they will not write books on 

 vast and complicated subjects, for the proper treatment 

 of which an author must have not only exceptional ability 

 but ample opportunities for philosophic study. So far as 

 we have examined the work, it has neither freshness of 

 thought nor charm of style. Dr. Mitchell mentions that 

 he has travelled in many different parts of the world. If 

 he was determined to write a book, he would have been 

 better employed in recording his reminiscences as a 

 traveller that in tediously discussing questions which 

 have occupied so many of the foremost intellects of the 

 present age. 



LETTERS TO THE EDITOR. 



[ The 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 ofi^ATVKZ, 

 No notice is taken of anonymous communications.^ 



A Magnetic Disturbance. 



Our attention having been directed for some days past towards 

 a spot of unusual size upon the sun's disk, we were not by any 

 means surprised to observe, as doubtless many of your readers 

 elsewhere also did, an aurora of great beauty on Saturday night 

 last ; nor was our anticipation of seeing a magnetic disturbance 

 portrayed upon the magnetograph records disappointed in the 

 morning, for when the sheets were changed and the photographs 

 developed, we saw that perturbations more violent than any 

 which had been recorded at Kew for the past ten years had 

 been in progress since about 5.45 a.m. of February 13. 



The magnets were very quiet on Friday, but early on Satur- 

 day morning they became disturbed. The easterly declination 



