598 



Mr. J. L. Glasson : Attempts to Detect the 



is likely that they would be extre^nely stable, and owing to 

 their small size and restricted external field they would be 

 extremely penetrating. They would, in fact, resemble closely 

 the neutral pairs by which Sir William Bragg proposed at 

 one time to explain the nature of X and y rays. It is 

 likely, however, that if a close collision with a heavy nucleus 

 occurred, there would be a disruption or re- arrangement of 

 the neutron or of the heavy nucleus, or of both with the 

 accompaniment of local ionization. In the experimental 

 work attempts have been made to secure this effect by 

 allowing the rays to fall on mercury and lead atoms. 



2. Experimental. — The arrangements naturally divide 

 themselves into two parts : (a) for production, and (6) for 

 detection. 



The tubes used for (a) have been of the two forms shown 

 in the figure. 



Fkr.-l. 



In the first pattern the window A itself served as the 

 cathode. In the second the cathode was of aluminium 

 provided with a large central tube down which the positive 

 rays were shot on to the window. The windows A and A' 

 were both made of brass with numerous perforations over 



