1904.] PUBLIC DOCUMENT — Xo. 33. 31 



THE INFLUENCE OF THE ATMOSPHERICAL 

 ELECTRICAL POTENTIAL ON PLANTS. 



BY N. F. MONAHAN. 



While cleetric'fil currents have such an important influence 

 upon the growtli and development of plants, as shown in the 

 preceding pages, so also does the electrical potential of the 

 atmosphere have an appreciable influence upon plant life. 

 The atmosphere is always charged to a higher or lower elec- 

 trical potential, either positive or negative. This has been 

 clearly shown by experiments conducted by the Weather 

 Bureau, United States Department of Agriculture, by Alex- 

 ander McAdie of the Blue Hill Observatorj , and by A. C. 

 Monahan of this station. The conditions ofoverninff the 

 amount of electrical potential of the air are not clearly 

 understood, but jNIonahan found, in a series of experi- 

 ments extending over nearly a year's time, that the air was 

 charged positively about 90 per cent, of the whole time at a 

 height of 30 feet from the ground. It is enough for us to 

 know, however, that the air is alwa^^s charged to a higher or 

 lower potential. It is the purpose of this paper to show in 

 a brief way some of the results of preliminary experiments 

 on the eflfects of atmospherical electrical potential on germi- 

 nation, and the gi'owth and development of plants. Fuller 

 accounts will be published later. 



Methods of Experiments and Apparatus used. 

 In all our experiments we have kept careful records of the 

 exact electrical potential. These records were made by the 

 use of a quadrant electrometer, designed by Sir William 

 Thomson for observations in atmospherical electricity, and 

 built by Eliot Bros, of London. In brief, the instrument 



