-oS 



NA TURE 



[April 13, 1905 



of which this is a continuation appears to have reached 

 a tenth edition. 



Section ii. is on the transmission of power. The first 

 example is a screw-driver, and the second a sewer rod 

 coupling. Another example is a cash conveyor, which, 

 as money is power, is no doubt an example of trans- 

 mission of power. On the next page is a viscosi- 

 meter, though what power is transmitted in this case 

 IS less obvious. Nor would one naturally expect four 

 examples of acoustic telephones to be found under this 

 heading. 



Section vii., on hydraulic power and appliances, com- 

 mences with some very sketchy ideas for wave motors, 

 and then describes a fog-horn buoy. There is no 

 reasonably good account of any one of the important 

 class of water turbines, but there is a quite impossible 

 design for a " multinozzle turbine," and next to this 

 a duplex steam feed pump. There is a figure of a Ven- 

 turi meter, but the description does not explain its 

 action, and the curiously inaccurate statement is made 

 that the differential velocitv produces a differential 

 pressure in two tubes with mouths turned in " oppo- 

 site " directions, and ends with the verv misleading 

 statement that "the measurement is "made by a 

 rneter. " The reader would not realise that " the 

 Venturi tube is the meter, and that what the author 

 probably mistakes for a meter is a recorder. 



Section viii., on air power, motors and appliances, 

 contains the "pneumatic ball puzzle," an "aerial 

 top," " grain elevators," " a magic ball," a " mega- 

 scope," a " sailing wagon," a " tail-less kite," and a 

 "sail-ngged merry-go-round "; but nothing about the 

 air-compressors, air-motors, and pneurnatic tools 

 which are now so important. 



Enough has been said to indicate the general char- 

 acter of the work. Many useful and important devices 

 are described amongst many others which are mere 

 mventors' schemes. There mav be readers who like 

 an olla podrida of this kind. 



Perhaps the most curious section, and we think the 

 longest, IS that on perpetual motions. About these the 

 author does not seem to have quite made up his own 

 mind. He does warn the reader in the preface that 

 the problem is " unsolvable. " But later, p. 363 he 

 remarks that " attempts to solve this problem would 

 seem so far, only to have proved it to be thoroughly 

 paradoxical," a statement which would hardly ge't 

 many marks in a science examination. Further we 

 5r£,fo!«* on the next page that, although admitting 

 difficulties in the way of its discoverv, " many 

 eminent mathematicians have favoured the belief in 

 the possibility of perpetual motion "; also that " it is 

 evident, therefore, that even mathematicians are not 

 agreed." 



Modern Theory of Physical Phenomena Radio- 

 activity, Ions, Electrons. By Augusto Righi 

 .Authorised translation by A. Trowbridge. Pp. xiii 

 + 165. (New York : The Macmillan Co. ; London : 

 Macmillan and Co., Ltd., 1904.) Price 55. net. 

 It is an interesting sign of the times that' so many 

 books have appeared during the last few months with 

 the object of explaining in non-technical words the 

 recent development of physical science. Part of the in- 

 terest shown in these subjects by the general reading 

 public IS, no doubt, of the unintelligent and wonder- 

 seeking order, which classes the more striking dis- 

 coveries of natural science with the latest sensation 

 of the law courts, or the cost of the flowers at a Trans- 

 atlantic ball. But it is fair to hope that some, at all 

 events, of those who read of the advance of knowledge 

 do so with a desire to comprehend the method, as well 

 as to admire the results, of scientific research. A 

 more widely spread application of the open-minded and 

 truth-seeking methods of science to the problems of in- 



XO. 1850, VOL. 71] 



dividual and collective life is, for the sake of the com- 

 munity, greatly to be desired. 



The little book before us deals in a light and in- 

 teresting manner with the conceptions of the physical 

 world which have been used of late in investigating 

 the phenomena of light, electricity, and radio-activity. 

 It states the results of recent inquiries in a clear and 

 intelligible manner, and, if the account of the methods 

 used in reaching the results sometimes seems in- 

 adequate, the difficulty of explaining those methods to 

 non-scientific readers may be urged as an excuse. 



.After an introduction, the book contains chapters on 

 electrolytic ions and electrons; electrons and the 

 phenomena of light; the nature of the kathode rays; 

 the ions in gases and solids; radio-activitv ; mass, 

 velocity, and electric charge of the ions and of the 

 electrons ; and the electrons and the constitution of 

 matter. The volume ends with a useful bibliography 

 of the subjects considered. 



The translation, on the whole, is well done, though 

 a certain want of crispness in the literary style is felt 

 in places. 



In a future edition one or two corrections would be 

 advisable. The period of vibration of light cannot be 

 " expressed by a fraction whose numerator is unity 

 and whose denominator is a number of fifteen places " 

 unless it is understood that " a fraction " is a fraction 

 of a second. The usual figure given to illustrate the 

 opposite deflection by a magnetic field of the a and |3 

 rays from radium exaggerates greatly the deflection 

 of the a rays compared with that of the /3 rays. This 

 exaggeration is legitimate, in fact, necessan,', in a 

 diagrammatic representation ; but it should be pointed 

 out in the text, or misconception of the relative mag- 

 nitudes of the two effects is sure to follow. In Thom- 

 son's method of determining the properties of the ions 

 produced by the incidence of ultra-violet light on a 

 metallic surface, the exactness is limited not only by the 

 differing velocities of the ions, as stated in the book. 

 Probably the ions are produced, not solely at the 

 metallic surface, but also in a layer of the gas of 

 finite thickness in its neighbourhood. Thus the dis- 

 tance from the surface reached against the influence 

 of a magnetic field may be different for different ions 

 even if their velocities be the same. 



The Journal of the Royal Ai;riciiltiiral Society. Vol. 



Ixv. Pp. clxvi -1-392. (London : Murray, 1904.) 

 The Journal of the Royal .Agricultural Society makes 

 its appearance this year in a rather slimmer form than 

 usual, due, however, more to the use of a thinner 

 paper than to a curtailment of the printed matter. The 

 affairs of the society bulk largely as usual, taking up 

 more than half the present volume, while the mis- 

 cellaneous articles, to which the ordinary reader turns, 

 only occupy about 150 pages. The volume is, in fact, 

 burdened far too much with rejxirts of council meet- 

 ings and committees, which have lost all interest for 

 the members by the time the annual volume reaches 

 them, and which would be much more to the point if 

 circulated as " proceedings " immediately after the 

 meetings and not reprinted here. 



The volume opens with a vivacious and readable 

 account of Sir Humphry Davy by Mr. H. B. 

 Wheatlev, who well brings out the charm and fascina- 

 tion of Davy's personality. But we cannot help 

 thinking Mr. Wheatley rates Davy's agricultural work 

 altogether too highly ; if any man is to be called 

 " father of the science " it is De Saussure, and not 

 Davy, who can be identified with no new discover}' or 

 novel point of view in agricultural science. In this 

 respect Daw w-as somewhat like Liebig ; both were 

 great men who had the power of getting the world to 

 listen to them, and when they turned their attention 

 to agriculture the influence they wielded, each in their 



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