448 Notices respecting New Boohs. 



5. The last results seem very difficult to reconcile with a 

 pulse theory. On the "material" theory propounded by 

 Professor Bragg no such difficulty arises. 



6. The secondary 7 radiation appears to be derived from 

 the primary by a process of scattering. This process gener- 

 ally involving a reduction in the subsequent penetrating 

 power of the ray affected. 



7. There appears to be reason to believe that the distribu- 

 tion of the scattered radiation depends to some extent upon 

 the hardness of the radiation which is scattered; also upon 

 the nature of the material in which the scattering is produced. 

 The softer radiation appears to be turned back to a somewhat 

 greater extent than the hard. Materials of high atomic 

 weight seem to be able to produce more complete scattering 

 than those of lower atomic weight. 



8. The absorption of 7 radiation which has already passed 

 through a thickness of one substance by screens of a different 

 substance may not in all cases give a true measure of the 

 absorption of the original radiation which has been effected 

 by the first screens. 



In conclusion, it is a pleasant duty for me to acknowledge 

 my indebtedness and sincere thanks to Professor Bragg for 

 his keen interest and advice during the progress of these 

 experiments. 



University, Adelaide, 

 Sept. 1908. 



XL. Notices respecting New Boohs. 



Annua ire pour Van 1909 publie par le Bureau des Longitudes. 

 Paris : Gauthier-Villars. 1 f r. 50. 



TN accordance with the new plan adopted by the Bureau, of 

 -*- selecting material from different branches of science in alternate 

 years, the present issue contains data respecting Metrology, Money, 

 Geography, Statistics, and Meteorology. The chemical and 

 physical data which appeared in 1908 will be again inserted in 

 1910. This year we may call attention to the very detailed 

 notices of M. Bigourdan on Variable Stars, and of M. Lallemand 

 on Movements and Deformations of the Earth's Crust. 



