September S, 1892] 



NATURE 



441 



further reading ; and the larger treatises, giving full ex- 

 planations of the matter in hand, will not be long unread. 

 In short this treatise lays the foundation for a thorough 

 microscopical training, entirely adapted to the wants of 

 medical students. 



It is printed only on one side of the page throughout, 

 so that the blank page is open for notes, and by using the 

 opportunities presented with wisdom, the book may 

 acquire, in the hands of an industrious student, a doubled 

 value. 



We may note that there are some points that even with 

 the restricted object of the book we think might have re- 

 ceived fuller, or even more accurate treatment. A fuller 

 treatment might certainly have been given to the subject 

 of " oblique light," which is very lightly touched ; but 

 which is none the less, to the partially instructed, whether 

 medical student or ordinary amateur, one of the most 

 prolific and frequent sources of erroneous judgment and 

 entire misinterpretation ; and we believe that no treatise 

 on microscopic work, whatever its object, can be tho- 

 roughly efficient without giving it grave and careful con- 

 sideration. 



On the other hand it would have given greater value 

 from the point of accuracy if the details given for the 

 " Centring and arrangement of the Illuminator," by which 

 is meant the sub-stage condenser, had been of a somewhat 

 later period. On the use — the right use — of the condenser 

 much of the best English work of the past quarter of a 

 century has been spent. Happily German microscopists 

 ;md opticians have during the past seven or eight years 

 begun to perceive the value, nay, indispensable import- 

 ance, of this apparatus, and the firm of Zeiss have, 

 through Abbe, made successively chromatic, and subse- 

 quently achromatic condensers of increasing value. We 

 trust they may be induced to follow English opticians and 

 make apochromatic condensers, especially one adapted 

 in numerical aperture to their latest optical triumph in 

 lenses, viz., that possessing a N.A. of i"6o ; the full value 

 of which as an apochromatic objective can never be seen 

 without it. It is a pleasure to note that Prof. Gage tells 

 us that " for all powers, but especially for high powers," 

 the condenser is of "great advantage." We believe it 

 for the highest results, even with " low " powers, to be 

 indispensable. But it will never be by the employment of 

 '• a pin-hole diaphragm . . . put over the end of the con- 

 denser' so that this aperture shall appear in the middle 

 of the field, that the best possibilities of the condenser will 

 be reached. The student is plainly told that the " optic 

 axis of the condenser and of the microscope should coin- 

 cide," but the best way of securing this coincidence is 

 certainly not stated. 



The blemishes of the book are nevertheless few, it has 

 a decided purpose, and there is a large sphere for its 

 action. We believe that another edition will not long 

 hence be called for in which its author will not find it 

 difficult to emend and expand it in certain parts, and 

 possibly still further to enlarge it, and we will add that 

 we think it may not only prove of value to the students 

 in the Anatomical Department of the Cornell University, 

 but also to others on both sides the Atlantic. 



W. H. Dallinger. 



NO. I I9j, VOL. 46] 



OUR BOOK SHELF. 



An Elementary Text- book of Magnetism and Electricity. 

 By R. Wallace Stewart. Univ. Corn Coll. Tutorial 

 Series. (London : W. B. Clive and Co., 1892.) 

 In this work Mr. Wallace Stewart presents us with 

 another of his excellent text-books on elementary science. 

 Just as his treatment of the subject was concise and clear 

 in his book on heat and light, so here he has followed the 

 same lines, and has placed before the student, especially 

 one who is preparing for the matriculation examination of 

 the London University, a course in magnetism and elec- 

 tricity which will give him a thorough knowledge of the 

 subject and a sound basis on which to make lurther study. 

 The illustrations and diagrams will be found to form a 

 valuable addition to the text, while the numerous ex- 

 amples at the end of each chapter, if thoroughly worked 

 out, should give a student a good insight into the art of 

 solving problems. 



Key to Arithmetic for Beginners. By J, and E. J. 



Brooksmith. (London: Macmillan and Co., 1892.) 

 This key will be welcomed by all those who are employing 

 Mr. Brooksmith's excellent arithmetic. It has been pre- 

 pared especially for the use of teachers, who will find it 

 a valuable aid in their work, but no doubt it will be largely 

 demanded by those who are studying this subject for 

 themselves, for much may be learnt by a judicious use of 

 such a book. The examples, so far as we have been able 

 to see, have been very carefully and concisely worked out, 

 and many difficulties that usually arise have here received 

 careful attention. 



LETTERS TO THE EDITOR. 



otHioHS ex- 



[TAe Editor does not hold himself responsible for opL 



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 of Nature. 

 No noiice is taken of anonymous communications. ^ 



International, Geological, and other Records. 



My friend Mr. Minchin's letter has opened a question that I 

 have been ruminating for a very long time We occasionally 

 hear of the organization of science, but the very ABC is at 

 present neglected, or carried out in a spasmodic and di.«jointed 

 manner. Let us take for example geology. We have .several 

 attempts at a catalogue and review of its yearly literature, of 

 which I give the following examples. First comes the " Geo- 

 logical Record," a publication very well in its way, but making 

 its appearance at irregular intervals, and often much behind time. 

 We have in Prof. Blake's Annual the attempt of a single in- 

 dividual to cope with a mass of literature that it is impossible for 

 him to read, and treating of questions that no single person is 

 or can be qualified to deal justly with. The very obvious result 

 of this is careless reviewing, and general dissatisfaction of most 

 authors whose papeis are submitted to the abstracting process. 

 I hope Prof. Blake will not take these words as a disparaging 

 appreciation of his attempt, which I think does him much credit 

 as a single-handed worker, but it will not satisfy the geologists 

 in general. Next we have the " Annuaire Geologique Universel," 

 for which great credit is due to Drs. Carey and Agincourt. 

 Here we have the geological literature of each country treated 

 separately, followed by a subject literature. Each article is 

 compiled by a specialist in his own branch, and one who is 

 able to form a just opinion of the work and appreciate the 

 salient points of it. Altogether the organization of the 

 " Annuaire " is on the right lines, but I understand it is not a 

 financial success, and I have very giave doubts if it will con- 

 tinue, because the supporters of one publication cannot be the 

 supporters of several. The motto " L'union fait la force" is as 

 true in this case as in any other. Then again there is not that 

 official character about it that there would be with international 

 co-operation, supported by governments, scientific societies, &c. 

 As two years' collaborator for the subjects of seismoloi;/ and 



