December 3, 1891] 



MATURE 



lor 



ducitur, Hypothesis vocanda est ; et Hypotheses, seu 

 Metaphysicae, seu Physicae, seu Qualitatum occultarum 

 seu Mechanicae, in Philosophia Experimentali locum 

 non habent." 



" Adjicerejam liceret nonnulla de Spiritu quodam sub- 

 tilissimo corpora crassa pervadente, et in iisdem latente, 

 cujus vi et actionibus particulse corporum ad minimas 

 distantias se mutuo attrahunt,et contiguae factae cohasrent." 

 " Sed base paucis exponi non possunt ; neque adest suffi- 

 ciens copia Experimentorum, quibus leges actionum hujus 

 Spiritus accurate determinari et monstrari debent." 



Now the present work of " Waterdale " is all Hypo- 

 thesis from beginning to end ; and there is no careful 

 detailed experiment to be found described in the book, by 

 which the various Hypotheses brought forward by him 

 can be tested. 



At a first glance the theory seems a revival of the 

 Cartesian Theory of Vortices, advanced in Newton's day 

 by Descartes to account for the motion of the celestial 

 bodies, and the difficulties attending this Theory are 

 pointed out by Newton in his " Scholium Generate" — 



" Hypothesis Vorticum multis premitur difficultatibus. 

 Ut Planeta unusquisque radio ad Solem ducto areas de- 

 scribat tempori proportionales, tempora periodica partium 

 Vorticis deberent esse in duplicata ratione distantiarum 

 a Sole," &c. 



This ancient theory is attributed by our author to F. 

 Major, in his recent work, " Spacial and Atomic Energy," 

 Parts I. and II. ; but the author himself gives, as the 

 primary reason for gravity, the mutual shelter to opposite 

 wave-energy afforded by two spheres or bodies ; and now, 

 if " Waterdale " is anxious to convert the scientific world, 

 he must utilize the quantitative theoretical results, worked 

 out by Lord Rayleigh, on the Apparent Attraction due 

 to* Vibration. 



The book abounds with curious unfamiliar dynamical 

 expressions, such as real^ vested, imposed, and specific 

 ponderosity, force of diversion, rectangular velocity, con- 

 center i7tg preponderating energy, film of transplacement, 

 &c., of which no definitions are given ; and altogether 

 the treatment is unconventional in the extreme. 



" Waterdale " concludes by asking that the question of 

 mechanical perpetual motion should be reopened, and that 

 pure mathematics should be once more applied to the 

 subject — 



^^ Perpetual motion has already been granted to us. 

 By the burning of coal and evaporation of water we have 

 work performed for us by Nature. Perpetuate the pro- 

 cess, and the work is also perpetuated. We have many 

 ways of acquiring this gift from Nature's stores, and one 

 more possible method need not startle the human mind.'' 



This method of ^«(7;j/-scientific argument is familiar to 

 us, in the newspapers, in the account and explanation of 

 Spiritualistic Phenomena. A. G. G. 



OUR BOOK SHELF. 

 Indischer Ozean : ein Atlas die Physikalischen Verhdlt- 

 nisse, und die Verkehrs-Strassen darstellend. (Ham- 

 burg : Deutsche Seewarte, 1891.) 

 These maps of meteorological and other physical data 

 for the Indian Ocean, while giving a very fair idea of the 

 prevailing conditions, are scarcely equal to the scientific 

 requirements of the present year of grace. 

 While it may be freely confessed that our knowledge 



NO. I 153, VOL. 45] 



of the area dealt with is yet very imperfect, and that the 

 scale of this handy atlas does not permit of great refine- 

 ments, there are many details to which exception may 

 fairly be taken. A few instances may be given. 



In the map of general depth no indication is furnished 

 of the extreme sparseness of the soundings from which 

 the various coloured areas are drawn. 



The current charts are depicted with a hardness and 

 regularity with regard to the different streams that are 

 scarcely consistent with nature. The ever-varying cir- 

 cumstances of the monsoons render the currents of this 

 ocean especially changeable, and it would be preferable 

 to indicate this characteristic by lines more broken. In 

 the sheet of the north-east monsoon period, the meeting 

 of the two main currents on the East African coast never 

 takes place so far south as is shown, nor is there any 

 justification for the peculiar direction of the line between 

 them to the eastward. 



It is a bold thing to attempt to portion the sea into 

 areas of definite surface specific gravities. The data are 

 very scanty. 



The pressure charts, which are given for the same 

 months as those published by the Meteorological Office, 

 and the map showing the relative prevalence of winds, 

 are good ; but here again the absence of the data on 

 which the various quantities in different areas are 

 founded is a serious flaw. 



The different maps are well got up, and bear further 

 witness to the general excellence of German lithography. 



Mechanics for Beginners. Part I. Dynamics and Statics, 

 By the Rev. J. B. Lock. (London : Macmillan and Co., 

 1891.) 

 Mr. Lock states that the work before us contains the 

 more elementary parts of the dynamics of a particle and 

 of the statics of parallel forces, arranged with some 

 additions from his " Elementary Dynamics and Statics." 

 The author's mode of treatment will be familiar to many 

 of our readers, and we need hardly say that Mr. Lock 

 slurs over no difficulty that presents itself to the young 

 student of this difficult subject. We have read the whole 

 of the text with much interest, and pronounce it to be ex- 

 cellent. A boy who has gone through this, and worked out 

 the examples in the manner shown him by the author, will 

 be well equipped for more advanced treatises. A novelty, 

 to which Mr. Lock draws attention, is a new form of 

 " that proof of the formula of accelerated motion which 

 depends upon the idea of average velocity." This proof 

 appears to be a satisfactory one. There is an interesting 

 combination of Morin's and Atwood's machines, which is 

 likely to furnish a useful illustration to students. The work 

 is split up into eight sections — rectilinear motion, motion 

 in one plane, forces acting at a point, parallel forces, 

 machines, uniform motion in a circle, energy, and the 

 pendulum. The arrangement has been made to meet the 

 special wants of the Science and Art Department. It 

 is suited for any junior students. Article i6 appears to 

 us to be likely to be too difficult for a boy ; if so, he can 

 pass on, and return to it subsequently. We have not 

 worked out the examples which accompany the several 

 chapters, and to which answers are given at the end. The 

 following errors we have noted : p. 1 7, 1. 8 up, dele a in 

 a«T ; p. 19, 1. 5 up, the first 2 N's should be N' ; p. 20, last 

 line, for 252 read 162 ; p. 52, 1. i, it would seem to follow 

 that " when one mass meets another mass of the same 

 velocity " they would not be said to impinge. What would 

 they be said to do ? P. 67, the term resolute is defined, 

 reference might be made to p. 92 ; p. 68, 1. i, dele a ; 

 p. 72, 1. 8 up, for Q read H ; p. 94, 1. 7, for an = read + ; 

 p. 115, 1. 7 up, read \o-x\ p. 139, 1. 2, for 4 read 3 ; 

 p. 205, last line, numerator, for cos a read sin a ; p. 208, 

 1. 20, supply^ ; p. 246, 1. 8 up, for second ^ read ^j. The 

 greater number of these errors are trifling, and will not 

 give the private student much trouble ; we have pointed 



