264 



Photograph VI is a trial plate to investigate the effect of various times 

 of exposures. Tlie exposures marked N are seen to be sliglitly darker 

 on the negative. Tliis seems to indicate that there is a slight effect 

 from the radiations of the Welsl)ach Iturner. Photographs A'll and VIII 



are to show wlietlier or not VI is due to a radiation. VII shows similar 

 results to VI and is taken under similar conditions. It was thought 

 that it might be due to heat, and to prove this a lead plate was placed 

 against the tin can, wliere It became lieated. Exposure A'llI is made with 

 the radiation cut off by the lead plate suspended between the source and 

 sulphide screen and shows similar results to VI and VII. The exposures 



