6 THE ROYAL SOCIETY OF CANADA 
A summary of the results obtained in these measurements at a 
number of points of observation is given in Table 1. 


TABLE I. 
ee q ” 
Observation Point. The number of ions in the receiver 
per cc. per second. 
i> Cambridge, England!) 22.70 9-03 
2. Bowland, Midlothian, Scotland........... 8-32 
3. The Physical Laboratory, Toronto...... 9-08 
4. The Meteorological Observatory, Toronto. 8-88 
5. The Lawn of the Meteorological Observa- 
bony) LOronto sess sess a es Abe eter 6-74 
6. The Atlantic Ocean, on 8.8. Grampian, 
sailing ex Glasgow, Sept. 16, 1911. 
Sepioe Uiveners sacs cuveee wietoe 6-42 
EP TO aes L 6-51 
RE EE Le 5-97 
DD VAR os eee on 5-42 
DE repeats Beets aceite ee 6-58 
Dy AN M aloe PFE 5-66 
DEAE fe Nie Mie Me EU 5-78 
Dara Ne ie he are 5-92 
Mean......6-03 6-03 


The final readings given in the table are the means of a number 
taken at each observation point. Those at Cambridge were made in a 
small brick cottage, the property of the Cambridge Scientific Instru- 
ment Co., and the thanks of the writer are due to the Manager, Mr. R. 
S. Whipple, for placing this building at his disposal and for very kindly 
assisting in taking practically all of the readings in that place. 
Those at Bowland were taken in a room in the residence of Mr. 
William Ramsay, a large stone structure, while those in the 
Meteorological Observatory, a stone building, were made with the kind 
permission of the Director, Mr. R. F.Stupart. The Physical Laboratory 
at Toronto, in which one of the sets of readings was made, is con- 
‘tructed of brick. 
From inquiries it was learned that in none of these four observing 
stations was there any radioactive contamination by reason of the intro- 
duction of radium or other radioactive substance. 
