504 Notices respecting New Books. 



The method is not well adapted to show the curve of 

 deflexions, although the deflexion at any point can be obtained, 

 if it is ever required, from the curve of bending moment. 



In conclusion, when the moment of inertia is constant and 

 the beam under the action of concentrated and uniform loads, 

 the original bending-moment curves become those w T hose 

 geometrical properties are well known, and it is a matter of 

 a few minutes to determine the reactions by the above method *, 

 and this not only applies to continuous beams but also to 

 beams fixed at the ends, as I have shown elsewhere j\ 

 1 am, Gentlemen, 



Yours faithfully, 



George Wilson. 



LIII. Notices respecting New Books. 



Radiation : An Elementary Treatise on Electromagnetic Radiation 

 and on Rontgen and Cathode Rays. By H. H. Fraxcis Hynd- 

 max, B.Se. With a preface by Professor Silvantts P. Thompsox, 

 D.Sc, P.R.S. London. Swan, Sonnenschein & Co. ; New 

 York, The Macmillan Co.', 1898. 



rPHE treatise of Mr. Hyndmaii may be described as a supplement 

 -*- to the ordinary text-books. He has not attempted to give an 

 account of the phenomena of radiation, such as will be found in 

 treatises on light or heat, except in cases where it is necesssary 

 for his purpose. His aim has been to furnish a summary of 

 recent research on radiation, including under that term not only 

 known transverse aether disturbances, but also the imperfectly com- 

 prehended cathode, Rontgen, and Le Pon rays. The scope of the 

 work is therefore a wide one, and the author can only give a brief 

 sketch of each research ; he atones, however, for this brevity by 

 copious references to original memoirs. The results of pioneer 

 work in any department of science are necessarily disconnected to 

 a certain extent ; they wait for some great discovery, either of 

 theory or fact, by which they are all explained, and until the 

 discovery is made they are not amenable to text-book treatment. 

 Under such circumstances classification alone is possible, and by 

 judicious classification the author has produced a very readable 

 and useful treatise. The discovery which will enable his treatise 

 to be converted into a text-book is that of the relation between 

 aether and matter. J.L.H. 



* As an example of this, take the case of a continuous beam of two 

 equal spans 100 feet long, loaded with a uniform load of 3 tons per foot 

 run, and a concentrated load of 20 tons placed on one span 40 feet from 

 the centre support, the moment of inertia of the cross-section of the 

 beam being constant. Ten minutes' work sufficed to show that the 

 reactions are 118*58, 390-84, 110-58 tons respectively. I doubt if this 

 could be done more quickly by any other method. 



t. The ' Mechanical Engineer,' June 18th, July 2nd and 9th. 



