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NATURE 



\June 14, 1 



serious defect in the work, and may be passed over with 

 this allusion. 



Very interesting are two introductory chapters on the 

 climatology and lithology of West Yorkshire, specially in 

 relation to plant-life, which many persons would doubt- 

 less gladly possess, apart from the enumeration of the 

 plants of the region. In the list of pelophilous (clay- 

 loving) plants, we note Spircea Filipendula, a. plant so 

 strictly associated with chalk in the south of England, 

 that we are surprised to find it among those characteristic 

 of clay and mud-soils. Perhaps it was a slip of the pen 

 for S. Ulmaria ? 



The total number of species of vascular plants enumer- 

 ated is 1042, whereof 995 are phanerogams, which is 

 equal to the whole phanerogamic flora of New Zealand, 

 even after allowing 40 off for " critical species " of various 

 genera. On the other hand, the vascular cryptogams of 

 West Yorkshire are only 47 against 138 in New Zea- 

 land, of which 120 are ferns. Fortunately for the New 

 Zealanders, and Australians too, for that matter, they are 

 free from the " horse-tails," which are such terrible pests 

 to farmers in some districts of this country ; but seven 

 species are indigenous in West Yorkshire. 



Cellular cryptogams are also included in Lees's 

 " Flora," and occupy about 250 pages. The enumera- 

 tions of some of the groups are exceedingly imperfect 

 — imperfect in consequence of their not having been 

 investigated — and it would have been much more con- 

 venient for the majority of workers had this class been 

 reserved for a separate volume. W. B. H. 



OUR BOOK SHELF. 



A Manual of Practical Assaying. By John Mitchell, 

 F.C.S. Edited by William Crookes, F.R.S. Sixth 

 Edition. (London: Longmans, Green, and Co., 1888.) 



Mitchell's " Assaying " is so well known to all whom 

 the subject concerns, that it is hardly necessary at present 

 to do more than announce the appearance of a new 

 edition. In this edition, as Mr. Crookes explains, much 

 new matter has been introduced, and matter which had 

 become obsolete has been omitted. Among the more 

 important of the additions are descriptions of the "auto- 

 matic sampling-machine," invented by Mr. D. W. Brun- 

 ton ; many new gas-furnaces and burners for the laboratory, 

 devised by Mr. Fletcher, Messrs. J.J. Griffin, and others ; 

 new blow-pipe reagents and operations ; new processes, 

 dosimetric, volumetric, and calorimetric, for the partial 

 and complete assay of iron ores, iron, steel, spiegeleisen, 

 &c. In the copper assay the American system of fire 

 assay is here, for the first time in this country, fully de- 

 scribed. In the assay of silver, the action of bismuth on 

 the ductility of this metal has received adequate atten- 

 tion. Much has been added about gold ores ; and 

 improved modes of assaying the precious metal and 

 detecting it in poor ores are given. The number of 

 woodcuts has been increased from 188 in the last edition 

 to 201 in the present edition. 



Asbestos, its Production and Use. By Robert H. Jones. 

 (London : Crosby Lockwood and Son, 1888.) 



This little book, written in epistolary style, though pos- 

 sessing little or no scientific value, contains an interesting 

 account of the " asbestos " mines of Canada, and of the 

 methods pursued in working the mineral in that country. 

 It is precisely ten years since the first Canadian 

 chrysotile mines were opened, and the annual yield at the 

 present time appears to be more than 2000 tons, so that the 



new locality is rapidly becoming an important rival to the 

 older and better-known asbestos mines of the Italian Alps. 

 The author gives a brief description of the mode of occur- 

 rence of the mineral in the Serpentine belt which traverses 

 the provinces of Megantic and Beauce in Quebec, and 

 prophesies a wider development of this industry in the 

 future ; he does not, however, supply any such details as 

 would suggest either the origin or the probable extent of 

 the Canadian " asbestos," and the book contains no 

 original observations of any scientific importance. The 

 author does not appear to be aware of the difference 

 between asbestos and chrysotile. The pages most inter- 

 esting to general readers are those which contain an 

 account of the latest uses to which the mineral is now 

 applied ; among which may be mentioned fire-balloons, 

 theatre-curtains, fire-proof paint, filters, and letter-paper. 



Industrial Instruction. By Robert Seidel. Translated 

 by Margaret K. Smith. (Boston : D. C. Heath and 

 Co., 1888.) 

 In the years 1882 and 1884 industrial instruction formed 

 the subject of much discussion in the Synod of the Canton 

 of Zurich. Herr Seidel, who had long devoted earnest 

 attention to the question, carefully answered all the 

 objections to industrial education which were raised in the 

 course of these debates ; and the substance of his replies 

 is embodied in the work translated in the present volume. 

 If there is still anyone who has doubts as to the value of 

 manual training in schools, he would profit largely by 

 reading this little book. Herr Seidel's main point is that 

 such training is absolutely essential in the interests of true 

 education, and in working out this view he displays great 

 intellectual resource and a thorough appreciation of the 

 laws of mental growth. He is not afraid that when the 

 need for this " new departure " is generally recognized 

 the task imposed upon teachers will be beyond their 

 capacities. The training of teachers for industrial in- 

 struction," he says, " offers no difficulty, and will not (as 

 has been asserted) by any means involve the necessity for 

 two kinds of teachers. The teacher can very well master 

 the new task, and if his prejudice has disappeared, will 

 very gladly undertake it. Probably the imparting of 

 industrial instruction will become a favourite employment 

 of the teacher, because the change refreshes and the 

 labour gladdens him." 



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 intended for this or any other part 

 op Nature. No notice is taken of anonymous communi- 

 cations.'] 



Electric Fishes in the River Uruguay. 



In Sir Horace Rumbold's " Great Silver River" (London, 

 1887), the author, when on the Upper Uruguay above Uru- 

 guayana, speaks of a "kind of Electric Eel (Gymnotus) called 

 here Rayo or Lightning, of the effects of contact with which, 

 very curious and unrelateable stories are told." 

 , The range of the Gymnoti is usually supposed to be con- 

 fined to the waters of the Orinoco and Amazons and their 

 affluents, so that it would be very desirable to ascertain what 

 this supposed electric fish of the Rio Uruguay really is. Perhaps 

 some of your readers in the Argentine Republic may be able to 

 assist us in solving this problem, which would be best done by 

 the transmission of specimens of the fish in question to the 

 British Museum. P. L. Sclater. 



3 Hanover Square, London, W., June 8. 



The Salt Industry in the United States. 



Mr. Ward in his letter to Nature (May 10, p. 29), 

 respecting the salt industry in the United States, makes no men- 

 tion of the important and numerous contributions to the 



