250 Mr. A. S. Eve on the Ionization of 



Before the voyage on the " Athenia " commenced, readings 

 were taken on three successive days at Montreal, on the roof 

 of my house, on the College Campus, and on the top of 

 Mount Royal. The values obtained averaged n + = 370, 

 n__ = 367. The results are extraordinarily small, being about 

 one third or one quarter of those usually obtained at 

 Montreal. The temperature was about 70° F. and there was 

 a conspicuous heat-haze over the country, and the low 

 readings were probably due to this haze. On the first day 

 of the voyage similar low values were found on the River 

 St. Lawrence, 25 miles above Quebec, about 100 miles from 

 Montreal. It may be stated that the mean of several 

 readings taken at Montreal during the winter and spring of 

 1905-6 are n + = 1400, n_ = l2U. But on Sept. 15, 1906, 

 when all the weather conditions appeared similar to those 

 on the sea voyage, I found at Outremont Golf Links, away 

 from the smoke of Montreal, n + = 768, ti_ = 717. 



On the voyage in the Gulf of St. Lawrence the means of 

 the readings were « + = 761, n_ = H3. But on the open sea 

 the average values were n + = 975, 7?_=783, ratio 1'24. 

 These figures are in fairly good agreement with those found 

 by A. Boltzmann, namely, n + = 1150, n__ = 800, ratio 1*4. 

 As the vessel approached the British Isles larger results 

 were obtained, n + = 1210, w_ = 1045. And again in the 

 Irish Sea, near the Isle of Man, the observations gave 

 n + = 1273, n_ = 872. Here the atmosphere was extremely 

 clear, so that the tops of the masts of distant vessels could 

 be seen whilst the hulls and lower parts of the masts were 

 hidden by the curvature of the earth. Such clear weather 

 is usually accompanied by high ionization, just as the haze 

 at Montreal probably caused the unusually low readings 

 there. In consequence of these meteorological conditions 

 the number of ions per c.c. near the British Isles was nearly 

 three times as great as in the basin of the river St. Lawrence. 



The whole series of observations are given in tabular 

 form, and are also exhibited in a chart. Each observation 

 consisted of two positive and two negative readings, but the 

 means of these are alone recorded. Too much weight must 

 not be attached to any particular reading, because all 

 observers find that the number of ions present per c.c. is 

 often subject to rapid and apparently capricious variations. 



The results have been given in ions per c.c, but they can 

 be reduced to electrostatic units per cubic metre bv multiplying 

 by 3-4 x 10- 4 . 



