Februarv 28, 1901] 



NATURE 



417 



hopelessly into totally unnecessary integration in order to 

 get back to the professorial logarithm. 



The nomenclature of photometrical quantities is dis- 

 missed in a few lines with the very true remark that 

 "the tendency toward particular nomenclature of 

 physical quantities has been carried to a burdensome 

 excess in many cases, until it has assumed the nature of 

 scientific fetichism." " The attempts " of Hospitalier are 

 alluded to, but the author has paid so little attention to 

 the matter that he falls into sad confusion in the use of 

 the expression " illumination." The word is used in half 

 a dozen senses — as a sensation, as a flux, as a quantity of 

 light, and so on. It is true that the "lux" of Preece or 

 Hospitalier are no guide, but the " carcel-metre " or the 

 unscientific " candle-foot," when once understood, leave 

 not the slightest ambiguity about the meaning of 

 " illumination." 



The chapter on standards of light is excellent, but the 

 table of comparisons of standards, taken from Laporte, 

 does not mclude the British candle. Only two items out 

 of a dozen appear to agree with the more complete table 

 of Palaz. The British candle, with all the refinements of 

 the gas referees, is not a unit which does credit "to 

 physical science, but it is at least as definitely known, 

 reproducible and measurable as any other standard of 

 light. 



The arrangement, illustrations and index are good ; 

 the spelling is English. A. P. T. 



OUR BOOK SHELF. 



The Nature and Work of Plants : an Introduction to the 

 Study of Botany. By D. T. MacDougal, Ph.D., 

 Director of the Laboratories, New York Botanic 

 Garden. Pp. xvii -t-2i8. (New York : The Macmillan 

 Co. London : Macmillan and Co., Ltd., -1900.) 

 This is a bright and readable little volume, in which 

 plants are treated of mainly from a natural history and 

 physiological point of view. It deserves to be success- 

 ful, if only as showing that it is possible to gain a 

 fairly considerable, and certainly intelligent, insight into 

 the ways of plants, and that without first mastering the 

 mass of technical detail which too often renders ele- 

 mentary books on botany so repulsive to beginners. 



The author commences with a general account of the 

 materials of which plants are composed, and of the struc- 

 tures of which they are built up, the student being led to 

 investigate for himself the different facts and prmciples 

 enunciated. The phenomena of reproduction, irritability 

 and the like are introduced as objects of observation, and 

 in such a way as to arouse, rather than by satiating to 

 quench, curiosity. The seed and fruit are more fully 

 dealt with, as they afford examples in which adapta- 

 tions to special purposes can be made out with some 

 degree of clearness, and their individual peculiarities 

 are well explained. If one feels some doubt as to the 

 wisdom of selecting the coconut as an introductory ex- 

 ample of a fruit, one cannot complain of the mode in 

 which its structure is treated. The very interesting case 

 of Xanthium, in which two fruits are contained in a com- 

 mon sheath,' one seed of which germinates in one year 

 whilst its fellow remains dormant till the following season, 

 will probably be new to some readers on this side the 

 Atlantic. 



A short chapter on plant societies closes the volume, 

 which may be warmly commended as one likely to excite 

 an .nterest in many people who fancy that the acquire- 

 ment of a more or less complicated vocabulary is an 

 essential preliminary to a scientific study of plants. 



NO. 1635, VOL. 62,'] 



Naturally, the book is not without its faults. Some of 

 these seem to be those of carelessness, of which there is 

 an example on p. 11 in the implication that a dried plant 

 consists of charcoal (I) and ash. But these defects are 

 not numerous, and do not seriously affect the general 

 excellence of the book 

 Practical Coal Mining. By George L. Kerr. Pp. 



X ■{■ 462. (London : Charles Griffin and Company, 



Ltd., 1900.) 

 In the vigorous outburst of technical literature that the 

 last few years have witnessed, the subject of mining has 

 not been forgotten, and the student of this subject has 

 his choice of a fair number of works of a high degree of 

 merit, amongst which those published by Messrs. Griffin 

 and Co. take foremost rank. It was therefore to be 

 expected that a new book on coal mining, issued by these 

 same publishers, ought to surpass anything previously 

 written on this subject, or at any rate to present features 

 of especial importance. It is to be regretted that these 

 anticipations have been very far from being realised, 

 and, indeed, that it is difficult to discover anything in the 

 work now under review that justifies its pubUcation. It 

 is very largely made up of extracts from the works 

 already referred to, as well as from others, nor are these 

 extracts by any means the worst part of the book. The 

 author's style is far from clear, and many passages might 

 be quoted that would be quite unintelligible to any one 

 who was not acquainted beforehand with the subject- 

 matter ; this obscurity of languages often merges into 

 inaccuracy and want of precision — the latter fault being 

 one of the most dangerous that could well be found in a 

 book intended to be placed in the hands of a student. A 

 couple of examples of this fault may be cited : on p. 3 

 the author writes that "the line at right angles to the 

 direction of 'dip' is called the 'strike,'" a definition that 

 is not true unless qualified by the statement that the line 

 referred to is a line within the bed ; it is obvious that 

 there may be an infinite number of lines at right angles 

 to the direction of dip, but only one of these is the strike. 

 Again, on p. 326, we find the following : " When two 

 shafts are sunk and connected by a passage, and the 

 density (weight) of air in the two shafts is equal, no 

 current of air will circulate, no matter what their 

 respective sizes may be." This, again, is only true if it 

 be postulated that both shafts are of precisely the same 

 depth, otherwise an air current may circulate. 



The author is weak whenever he touches upon 

 scientific ground ; he uses mechanical formulas without 

 apparently appreciating their limitations, as, for instance, 

 when he applies formulas for the bending of columns, 

 ignoring the fact that these are only applicable within 

 the elastic limit. Similarly, his mechanical conceptions 

 of the work done by the winding engine (p. 221) are 

 incorrect. That his chemistry is not much more satis- 

 factory may be judged from the occurrence of such 

 phrases as "glycerine nitrate" for nitro glycerine, &c. 



The best chapter in the book is that on " Modes of 

 Working," the methods of coal-getting in use in Scotland 

 being well described. Indeed, had Mr. Kerr confined 

 himself to a small book describing merely those points 

 in which Scotch practice differs from the English, 

 notably in shaft-sinking, coal-getting and haulage, he 

 would have produced a contribution of distinct value to 

 the literature of coal mining, a phrase that can, un- 

 fortunately, not be applied to his present more 

 ambitious attempt. H. Louis. 



Bookkeeping for Business Men. By J. Thornton and 

 S.W.Thornton. Pp. vi-fi85. (London: Macmillan 

 and Co., Ltd., 1900.) Price y. 6d. 

 Bookkeeping is only the application of common-sense 

 principles to the classification and systemisation of ac- 

 counts. Its purpose is to show how the financial facts of 

 a business may be expressed in the clearest and shortest 



