448 



KEPOET 1881. 



The fact of frequency of negative tension with rain has long been 

 observed ; bnt it is found that it is almost always accompanied with large 

 and rapid excursions on the side of positive tension, and therefore the 

 averao"e hourly value of the tension during such periods is seldom low. 



One year's data can scarcely be considered to give perfectly decisive 

 results ; but it is believed that the following conclusions may be drawn 

 from the observations now under discussion. 



In the first case, it is found that genei-ally the relations differ in summer 

 and in winter ; their variations are therefore given as well as their means. 



Table V. — Values of Electrical Tension corresjjonding to varying 



amounts of Cloud. 



1st. Wind — direction. It is found at Kew that for the year the maxi- 

 mum tension (109 volts) occurs with north-westerly winds, and the 

 minimum (64) with south-easterly winds ; but for the summer months the 

 tension is greatest (109 volts) with an east wind, and lowest (50) with a 

 north wind; whilst in winter the conditions are almost reversed, and 

 northerly and north-westerly winds have the strongest tensions — 133 

 and 128 volts respectively, and south-easterly the weakest, with 48, See 



Table III. 



These results may be influenced by the intensity of the wind, as it is 

 found that, contrary to what one would imagine, light winds have a higher 

 potential than strong breezes, the average tension being in the latter case 

 but about one-third of that in the former. 



