Intelligence and Miscellaneous Articles. 228* 



ionization by X-rays is effected indirectly by the cathode rays 

 which spring from the X-rays, and that there is no direct ionizing 

 action of the primary rays. The cathode rays have a range in air 

 of two or three millimetres at the outside, and only the more 

 penetrating have as much as that. All but a very small fraction 

 of the ionization is to be found less than a millimetre away from 

 the primary stream of X-rays. 



I am, Tours &c, 



W. H. Bragg. 



LONGITU- 

 DINAL AND TRANSVERSE MASS OF AN ELECTRON." (Phih 



Mag. June 1911.) 



The expression jrr — ^— -^r given in the first equation in the 

 paper should really be 



?5 = ?E *£ + ^5 <*£-+ ?5 ?r 



d* dp bt d<? d* dr "dt* 



with similar expressions for -57 and — — , The terms omitted in 



o* ot 



the paper, however, obviously always vanish for the case 



p = v, q = r=0, which is the one treated in the paper, for the q 



and r derivatives of U vanish from symmetry, and the omitted 



derivatives of V and "W vanish, because they involve either q or r 



as a factor. Thus the remainder of the argument in the paper is 



exact. "W. F. Gr. Swann. 



ANNUAL TABLES OF CONSTANTS AND NUMERICAL DATA 

 CHEMICAL, PHYSICAL, AND TECHNOLOGICAL. 

 International Commission of Publication 



Appointed by the Vllth International Congress of Applied Chemistry 

 in London, 2nd June, 1909. 



At the International Congress of Applied Chemistry held in 

 London in 1909 an International Commission was appointed for 

 the purpose of compiling and publishing Annual Tables of Con- 

 stants and Numerical Data ; and this Commission was subsequently 

 accorded the patronage of the Association of Academies at the 

 meeting of that body held in Eome in 1910 (' Nature,' May 26, 

 1910, p. 371). 



According to the programme drawn up by the Commission the 

 Tables published in any one year are intended to contain all the 

 numerical data likely to be of interest in connexion with Chemistry, 

 Physics, and allied Sciences, pure and applied, to be found in the 

 literature published during the previous year. The data are to 



