534 



NA TURE 



[April 9, 1908 



well known has led to an unfortunate use of the 

 terms caterpillar and chrysalis, which are here applied 

 to the zosea and megalopa stages of the crab. 



We can understand the desire on the part of the 

 author to bring- home to the children the fact that the 

 zosea and caterpillar represent the larval stage in the 

 life-histories of crab and butterfly, and that the 

 chrysalis of the butterfly and the megalopa of the 

 crab are also corresponding stages, but to call a 

 zoaea a caterpillar and a megalopa a chrysalis is 

 carrying comparison too far. 



Frank Balfour Browne. 



Deviations des Compas. By Pierre Engel. Pp. vi + 

 64 ; with 3 plates. (Paris : Gauthier-Villars, 1907.) 

 Price 2.75 francs. 

 The brief introduction well describes the subject- 

 matter of the book. It is divided into four parts. 

 The first consists of a theoretical study of the 

 magnetic field of a ship. It is quite simple, and in- 

 volves no knowledge of mathematics beyond the 

 rudiments of trigonometry. The second part _ is 

 equally elementary in its treatment, and deals with 

 the action of the field in question on a magnetic 

 needle, together with an outline of the principle of 

 compensation. The third part deals with the com- 

 pensation of the Thomson or Kelvin compass, while 

 the fourth part consists of various information and 

 remarks, both general and particular, relating to the 

 Thomson compass. Of the plates, the third and 

 fourth are charts of the world showing curves of 

 equal horizontal intensity and equal magnetic in- 

 clination respectively. Ensign Engel has produced a 

 book which should be of great use to naval ofificers, 

 to whom a knowledge of the principles of the modern 

 mariner's compass is indispensable, but to whom a 

 highly mathematical treatment would be prohibitive. 



Bulletin of Miscellaneous Information. Royal Botanic 

 Gardens, Kew. Pp. 421 + 152. (London: Darling 

 and Son, 1907.) Price 5s. 

 This volume of the Kew Bulletin is the second of the 

 regenerated series. For the most part the contents 

 are connected with systematic or economic botany. 

 Herbarium workers have contributed lists of new 

 flowering plants from Africa and elsewhere, reduc- 

 tions of the Wallichian herbarium, identifications of 

 algae and fungi, and special articles. The rubber boom 

 is reflected in several articles, notably in the accounts 

 of Guayule rubber, obtained from Parthenium argen- 

 tatum, and of Mgoa rubber, the product of the East 

 .African tree Mascare\i}iasia clastica. Various ad- 

 ditions have been made to the wild fauna and flora of 

 the gardens, the most important being the list of 

 lepidoptera compiled by Mr. .'\. L. Simmons. Notes 

 on the cricket-bat willow and on gardens and parks 

 in South Wales represent the work of members of the 

 gardens' stafl', and articles have been contributed from 

 India and Africa by former members of the staff. 



Tlie Will to Doubt: an Essay in Philosophy for the 

 General Thinker. By Alfred H. Lloyd. Pp. xi + 

 2S5. (London : Swan Sonnenschein and Co., Ltd., 

 1907,) Price 45. 6d. 

 The thesis defended in this, the latest, volume of 

 I'rof. Muirhead's ethical library is that doubt is no 

 mere negative of belief, but a positive element abso- 

 lutely necessary to real life. It is true that the 

 common-sense view of the world is full of contradic- 

 tions that furnish abundant food for doubt, and that 

 no less must be said of the more special and abstract 

 views which constitute the sciences. But though 

 Prof. Lloyd thus agrees with Mr. F. H. Bradley in 

 holding that our experience at all its levels is " riddled 

 NO. 2006, VOL. 77] 



with contradictions," he does not follow the Oxford 

 philosopher to his famous conclusion that all experi- 

 ence is therefore only of " appearance " and not of 

 "reality." In his view, on the contrary, contradic- 

 tion actually serves experience by holding it down to 

 the real world which it would otherwise miss. It 

 follows that the " doubter's world " must always 

 present certain positive features which will accord with 

 the principles of Descartes, the typical modern 

 doubter. Among these will be found psychophysical 

 parallelism and " the immortality of whatever is 

 indeed real." 



Prof. Lloyd's argument is interesting, and is ably, 

 if not always convincingly, developed, but suffers from 

 his somewhat perverse and strained efforts after 

 brilliance of style. He has, moreover, shown more 

 courage than prudence in choosing a title which in- 

 evitably suggests comparison of his work with that 

 of his compatriot. Prof. William James. 



LETTERS TO THE EDITOR. 

 [The Editor does not hold himself responsible for opinions 

 expressed 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 0/ Nature. 

 No notice is taken of anonymous comtnunications.] 



An Annotated Copy of Newton's " Principia.' 



It may interest your correspondent (p. 510) to know that 

 Le Neve, in his " Pedigrees of Knights " (Harleian Sec, 

 1873, viii., p. 192), states that Sir Demetrius James, of 

 Itham, was knighted on May 10, 1665. An account of 

 the family may be found in Hasted's " History of Kent," 

 vol. ii., p. 247. 



Much information about the preparation of the second 

 edition of the " Principia " may be found in Brewster's 

 " Memoirs of Sir Isaac Newton," vol. ii., p. 273 et seq., 

 but it is needless to burden your columns with quotations 

 from so accessible a book. Two specially bearing on the 

 point at issue will suffice : — " Even in November 1702, 

 when he [Newton] was visited by Bd. Greves, who saw 

 in his hands an interleaved and corrected copy of the 

 Principia, he would not acknowledge that he had any 

 intention to reprint it." " In a letter dated October 11 

 [1709], Newton intimated to Cotes that he had sent him 

 by Mr. Whiston ' the greatest part of the copy of his 

 Principia, in order to a new edition,' thanked him for his 

 letter of the 18th of August, and requested him not to be 

 at the trouble of examining all the Demonstrations, but 

 ' to print by the copy sent him, correcting only such faults 

 as occur in reading over the sheets,' which would entail 

 upon him ' more labour than it was fit to give him.' " 



The results of Mr. Smith's further inquiries will be 

 awaited with interest. W. R. B. Prideaux. 



Reform Club, Pall Mall, S.W., April 2. 



Proposed Alteration in the Calendar. 



With reference to the proposed alteration of the calendar 

 so ably discussed by " W. T. L. " in Nature of March 26, 

 it seems to me that the drastic scheme advocated by Mr. 

 Pearce is not only inadmissible because interfering with 

 the continuity of the weeks, but it is not the simplest 

 scheme that could be adopted, even allowing the inter- 

 ference proposed. 



The Positivist Calendar agrees with Mr. Pearce's pro- 

 posal in that it divides the year into fifty-two weeks with 

 a supernumerary day which is not included in any week, 

 and with two such supernumerary days in leap years. 

 The two calendars are also alike in that these super- 

 numerary days are not included in any month. But the 

 Positivist Calendar is the siihpler of the two in that it 

 makes all the months of the same length, namely, four 

 weeks ; and Blackstone informs us that in law a month 

 means " 28 days, unless otherwise expressed." 



