October i, 1903] 



NATURE 



525 



This second volume of the treatise, which is de- 

 voted to the "compass and deviations aboard ship," 

 can hardly be fully mastered until after reading the 

 first volume, but it is in a great measure complete in 

 itself, especially to those who have already some know- 

 ledge of terrestrial magnetism. All will agree with 

 the author of this book when he insists upon the 

 necessity for every navigator knowing as much as 

 possible about his compass and that magnet — his ship 

 — which is ever in antagonism to the earth, which does 

 its best to direct the compass to magnetic north. 



Of the five parts into which this volume is divided, 

 part ii. treats of the manufacture of the liquid com- 

 pass (the only kind in use in the U.S. Navy), giving 

 in full detail the principles of magnetism and 

 mechanics connected with its construction and use 

 afterwards. 



In part iii. the ship is shown to be a magnet by 

 experimental magnetic surveys of ships illustrated by 

 diagrams. The physical representation of the theory 

 of the deviation of the compass is fully given, but 

 decided exception must be taken to the instructions for 

 determining the position of the compass after the ship 

 is launched. It is then too late, and the experienced 

 Superintendent of Compasses and the constructors 

 should long before have agreed upon a place for it 

 in the ship's drawings, and afterwards worked in 

 harmony to keep iron fittings at a proper distance. 



Part Iv. traats of the mathematical theory of the 

 deviations of the compass, and here, as in other of the 

 mathematical investigations he gives, the author gives 

 valuable assistance to those who are not skilled mathe- 

 maticians by " filling up those gaps in the sequence 

 of the formulas that often yawn forbiddingly." 



On the question of compensation of the deviations 

 of the compass, to which part v. is devoted, we have 

 the least satisfactory part of the book. Thus the 

 formula for correcting the heeling error with spheres 

 in place is very convenient in practice, but not mathe- 

 matically correct. The instructions for compensating 

 the secondan,^ part of the quadrantal deviation known 

 as coefficient E by spheres are incorrect. Again, the 

 residuary quadrantal deviation, after compensation, is 

 described as "practically constant the world over"; 

 but this is certainly not so in the example given of the 

 " Machias," where, between Aden and Pechili Strait, 

 the quadrantal deviation differed nearly 3°, as might 

 be expected where soft iron correctors are placed near 

 the long powerful needles of the Ritchie compass. 

 Further, the Flinders bar will not compensate any 

 important part of the heeling error due to soft iron 

 as here proposed. 



There is much to recommend this book to the 

 student, both as regards the mathematical treatment 

 of the subject and for its numerous explanatory 

 diagrams. Its weak point lies in the parts relating 

 to the application of theory to practice, which require 

 modernising and a carefulVevision. E. VV. C. 



Comity international des Poids et Mesures. Proces- 

 Verbaux des Sciences. Deux. S^rie. Tome ii. 

 Session de 1903. Pp. 170. (Paris : Gauthier-Villars, 

 1903-) 

 The Proces-Verbaux recently issued by the Comit^ 

 international des Poids et Mesures refers to their meet- 

 ing at Paris in April last. The committee included 

 Dr. W. Foerster (president). Prof. P. Blazerna (secre- 

 tary). Dr. Benoit (director of the bureau), and MM. 

 Arndsten, D'Arrillaga, de Bodola, Egoroff, Gautier, 

 Hasselberg, and von Lang. Their proceedings 

 mainly had reference to the work at their bureau 

 (Pavilion de Breteuil, Sevres, Paris) for the current 

 year, including the consideration of the annual ex- 

 penses of the committee (100,000 francs). 



NO. 1770, VOL. 68] 



The committee lament the death of their distin- 

 guished colleague. Prof. A. Cornu, on April 12 last, 

 and also of Dr. H. von Wild, September 5, 1902, an 

 honorary member of the committee. They announce 

 th-^ unanimous election on the committee of M. E. 

 Mascart, and of Dr. A. Chappuis as an honorary 

 member. Count de Macedo (Portugal), Dr. A. Michel- 

 son (United States), and Mr. H. J. Chaney (Great 

 Britain) were unable to attend the present meeting. 



During the past year the verification of length 

 standards at the bureau included standards for the 

 Board of Trade, the Education Department, the 

 National Physical Laboratory, and other authorities in 

 England. On the application of the British Govern- 

 ment, indeed, an important work was undertaken by 

 the committee, that of the graduation and verification 

 of a new linear standard of the metre and yard, a 

 standard made of iridio-platinum, X section. 



Although the scientific work of the bureau last year 

 does not appear to have covered a wide field, it has 

 followed important paths, as in some investigations 

 (Appendix iii.) as to the linear expansion by heat of 

 platinum, iron, nickel, steel, glass, and quartz, and 

 the results reported by the committee are now prob- 

 ably among the most authoritative of such thermo- 

 metric investigations. Dr. C. E. Guillaume also adds 

 (Appendix i.) an essay on the theory of the alloys of 

 steel and nickel, and M. E. Sauvage (Appendix ii.) an 

 account of an international series of screw-threads, 

 based on metric measure, as formulated at a congress 

 held at Zurich in 1898-1900, a series which appears 

 to be now adopted for engineering purposes in France. 



Flora of the Island of Jersey. By L. V. Lester 

 Garland. Pp. xv + 205. (London: West, Newman 

 and Co., 1903.) 



Although in most parts of the country a botanist can 

 generally make a goodly collection of plants within a 

 day's journey of his residence, there is always a desire 

 to visit those localities in the British Isles which have 

 a special flora of their own. Such are the Scotch 

 mountain ranges, the counties of Devon and Cornwall, 

 and by no means the least interesting to the southerner, 

 the Channel Islands. On these visits it is a great 

 boon to have a flora which will give the information 

 where certain plants may be sought. For Guernsey 

 and the adjacent islands of Aldemey and Sark, Mr. 

 Marquand has published records, and no less welcome 

 is the compact little book which Mr. Lester Garland 

 has compiled on the flora of Jersey. The book pre- 

 sents one essentially new feature, since the system 

 adopted is that of Engler. Some excuse is offered for 

 the innovation, but there can be no question that 

 Engler's system is bound to supplant that of the 

 " Genera Plantarum," and considerable credit is due 

 to the author for acting up to his convictions. In 

 conformity with this change some of the generic names 

 have been altered, and Erucastrum, Lobularia, and 

 Parentucellia take the place of others more familiar; 

 for the same reason Tillaea muscosa, L., becomes 

 Crassula Tillaea, Lester. No trouble has been spared 

 to test uncertain or critical species and records, and 

 the notes on these are sound and practical ; also dis- 

 tinction is made between native plants and aliens. 

 The genus Centaurea serves to illustrate the author's 

 caution and care; he declines to split up Centaurea 

 nigra into uncertain varieties, queries Centaurea 

 scabiosa., accepts Centaurea scabra, and classes the 

 species cyanus, paniculata, calcitrapa, solstitialis 

 among the aliens. The last few pages are devoted to 

 an account of the geographical distribution and 

 affinities of species, and these complete a book which, 

 in addition to its convenient form, is to be recom- 

 mended for its extremely practical and scientific value. 



