May 1 6, 1895] 



NA TURE 



53 



seiches are not always associated, for in some cases the 

 former have not been accompanied by the latter. The 

 difficulty is undoubtedly a serious one, and it is thus met 

 by Prof. Forel. In an earthquake the undulator)- mo\e- 

 ment is variable in character. In some cases it affects a 

 pendulum seismograph, in others it does not ; much 

 depending on the rate at which the shock travels. If this 

 be quick, it will not produce a perceptible undulation to 

 a mass of water ; if it be slow, it will set up a very 

 sensible movement. Thus an earthquake of the latter 

 type will produce a seiche, but not one of the former. 

 There is much to be said in favour of this hypothesis ; 

 but further seismographic observations are required to 

 show that there is a real coincidence between the nature 

 of the earthquakes and the occurrence of the seiches. 



.More than one point of interest is discussed in the 

 section dealing with optical questions. The .Swiss 

 lakes, as is well known, varj- in colour, some having a 

 distinctly green tint, but others, and especially the Lake 

 of Geneva, being noted for the exquisite blue of ihe water. 

 To facilitate comparative observation. Prof Forel has 

 constructed a scale of colours, beginning with sulphate 

 of copper, as the pure blue, and representing the effects 

 of chromate of potash added in proportions commencing 

 with 2 and ending with 65 per cent. After a careful 

 study of the whole question, he comes to the conculsion 

 that the colour of the water depends not merely on the 

 quantity of minute mineral matter present in a state of 

 suspension, but also on the amount present in solution. 



The third point, the chemistrv' of the water, is also very 

 interesting. The author has collected together a large 

 number of analyses already published, has added some 

 others, and discusses the whole. These exhibit differences 

 more considerable than we might have expected ; for 

 instance, the residue after evaporation varies from 160 

 to 218 mgs. per litre. These differences, allowing for 

 possible errors, are probably due primarily to the affluents 

 of the lake, the waters of which are long in becoming 

 completely mixed with the main mass. The principal 

 •constituents of this residue are carbonate of lime, sul- 

 phate of lime, and carbonate of magnesia, the amounts 

 being variable. Evidently they depend partly upon the 

 time of the year, for in two samples, drawn from the same 

 locality in Januar)- and in May, the numbers in the 

 one case were as 3'3 : 26 : i, in the other 37 : 1-4 : i. 



The volume, in short, is full of valuable matter, and 

 worthy of its predecessor. As we said of that, it is 

 a little too diffuse for a scientific treatise, but it was 

 necessar)-, as the author then explained, to write it so 

 as to attract a larger circle of purchasers. 



T. G. BONNKV. 



OUR BOOK- SHELF. 

 A Catalogue of the Books and Pamphlets in the IJbrarv 

 of the 'Manchester Museum. Hy W. E. Hoyle, .M..>\'., 

 K.R.S.E., Keeper of the Museum. (Manchester : J. E. 

 Cornish, 1895.) 



Tlll.s catalogue, of 292 pp., owes its appearance in print 

 to private enterprise, and is noteworthy as being classified 

 according to the " Dewey Decimal System," under which 

 each digit composing the registration number of a book 

 marks a distinct narrowing in its significance, and for 

 the arrangement under each class by Cutter's " Decimal 



Author Table," whereby each book receives a number 

 which is virtually an abbreviation of its author's name. 

 Thus, that " 597-o94i ^■a 21 " denote the second, and 

 " 597094 1 Va 2 " the original edition of Yarrell's " Histor>- 

 of }5ritish Fishes," may appear perplexing ; but it is 

 claimed by the advocates of the Dcwey-Cutter systems 

 that however much the library may grow, these numerical 

 combinations will remain, and that they allow for maxi- 

 mum extension with minimum disturbance. 



The classified catalogue upon which we have commented 

 covers 230 pp., and is followed by a 5upplementar>' 

 "author catalog^ue." The author modestly remarks in 

 his preface, that the volume is " the work of one who 

 is not a professional librarian." The labour of compilation 

 has been great : and this catalogue, like all else that its 

 author has put before the world, bears strongly the stamp 

 of thoroughness and accuracy. We cordially recommend 

 it to our university and public librarians, not, however, 

 without a fear that they may adjudge it dangerous in its 

 over-elaboration. 



An index of subjects is appended, and Russian names 

 have been transliterated according to the system advocated 

 in our pages (N.^TURE, vol. xli. p. 396), and adopted in 

 many of the principal scientific libraries. 



A Course of Elementary Practical Bacteriology, including 

 Bacteriological Analysis and Chemistry. Hy A. .-X. 

 Kanthack, M.D., and J. H. Drysdale, M.B. (London : 

 Macmillan, 1895.) 



A LITTLE volume of 127 pages, primarily intended to 

 carry candidates for diplomas in Public Health through a 

 three months' course in bacteriology, and not pretend- 

 ing to be more than a laboratory guide. The instruc- 

 tions are extremely brief, and for the most part unaccom- 

 panied by any theoretical explanation. This entire 

 divorce of theory and practice is, in our opinion, not 

 unattended with danger, often leading the student to 

 unintelligently cram the details of methods without having 

 any proper understanding of the principles involved. It 

 is frequently forgotten that the chief object of laboratory' 

 work should be to gain a living knowledge of a science, 

 rather than the acquisition of mere dexterity in its prac- 

 tical technique. The exercises are, as we should anticipate 

 from the experience and standing of the authors, well 

 chcsen, thoroughly representative, and cover a large 

 amount of ground. On the other hand, some statements 

 made without qualification may easily give rise to mistakes 

 if accepted without reserve. Thus we are told that it is 

 often possible to give a definite opinion in from eighteen 

 to forty-eight hours, as to the jjresence or absence of 

 cholera vibrios. Recent researches, however, go more 

 and more to show that it is by no means so easy as was 

 supposed to give a correct " definite opinion " as to the 

 identity of this or any other particular micro-organism. 

 We doubt whether bacteriology is sufficiently advanced 

 to admit of treatment in quite such a final and hard and 

 fast manner as it receives in this text-book ; but we are 

 told that these pages are not to supplant the demonstrator, 

 and we would add that they should be carefully supple- 

 mented by the teacher. If thus employed, this work 

 should prove a very valuable addition to the bacterio- 

 logical literature of our country. Especially welcome is 

 the inclusion of the principal methods for the detection of 

 some of the chemical products of bacterial life. 



Primer of Navigation. \\\ .\. T. Flagg. (London : 

 Macmillan, 1894.) 



Mr. Fl.\c.i;'s little primer can be strongly recommended to 

 all beginners ; it is the .\ 1! C of the art of navigation. 

 Ever>' step is explained in the most simple and accurate 

 manner ; and for students depending upon self-instniction, 

 a better or more clearly written primer would be difficult 

 to imagine. 



NO. 1333, VOL. 52] 



