lOO 



ROYAL SOCIETY OF CANADA 



2. — Measurements made along the waterfrojit of Toronto Bay. 



A second series of measurements was made with the lead cylinder 

 referred to in the first portion of the paper as No. 1, after it had reached 

 what has been referred to above as the steady condition, obser\^ations on 

 the ionization being taken at different points along the water front of 

 Toronto Bay. 



The results given in Table X shew a total decrease of 9 ions per 

 c.c. per sec. from the value of " q " obtained in the laboratory, due to 

 the screening action of the water, and they seem to indicate in addition 

 that the ionization over sand banks washed up by the waves was but 

 little greater than that over water even of a considerable depth. 



Dec. 28th. 



TABLE X. 



Lead Cylinder 1, in steady state. 



This result is probably due to the fact that any radioactive sub- 

 stances originally present in the sand have been washed away by the 

 action of water. 



In this connection it is important to note that in making these 

 determinations of the conductivity of air enclosed in lead receivers it 

 was frequently observed tha^- in the measurements on the surface of the 

 lake with newly cleaned lead cylinders, filled \vith freshly filtered air, 

 the drop in conductivity observed was invariably about 50 per cent less 

 than th^ drop obtained with lead cylinders which, after being well cleaned 

 and filled with clean air, had been allowed to stand long enough to reach 

 Ihe steady state. 



