THE ADVANCE OF SCIENCE 87 



The beta rays are streams of corpuscles similar to 

 those given off by the cathode in a vacuum tube. 

 They are charged with negative electricity and travel at 

 the velocity of 100,000 miles a second. They are far 

 more minute than the alpha particles. Their mass is 

 equal to the one-thousandth of a hydrogen atom. They 

 produce the major part of the photographic and phos- 

 phorescent effects of the radium rays. 



The gamma rays are apparently the same, or nearly 

 the same, thing as the X-rays of Rontgen. They are 

 probably not particles at all, but pulses or waves in 

 the ether set up during the ejection of the corpuscles 

 which constitute the beta rays. They produce the 

 same effects in a much smaller degree as do the beta 

 rays, but are more penetrating. 



The kind of conceptions to which these and like 

 discoveries have led the modern physicist in regard to 

 the character of that supposed unbreakable body the 

 chemical atom the simple and unaffected friend of our 

 youth are truly astounding. Nevertheless, they are 

 not destructive of our previous conceptions, but rather 

 elaborations and developments of the simpler views, in- 

 troducing the notion of structure and mechanism, 

 agitated and whirling with tremendous force, into what 

 we formerly conceived of as homogeneous or simply 

 built-up particles, the earlier conception being not so 

 much a positive assertion of simplicity as a non-com- 

 mittal expectant formula awaiting the progress of know- 

 ledge and the revelations which are now in our hands. 



As I have already stated, the attempt to show in 

 detail how the marvellous properties of radium and 

 radio-activity in general are thus capable of a pictorial 

 or structural representation is beyond the limits of the 

 present essay; but the fact that such speculations 



