134 PROCEEDINGS OF THE AMERICAN ACADEMY 



The observatory at Blue Hill is provided with a self-registering 

 anemoscope and a self-registering anemometer. It was originally 

 intended to get a record of the potential variations, and compare it 

 with the records of these two instruments. Unfortunately, botii had 

 to be returned to the maker for alterations, because of changes made 

 in the building. It also became a2:)parent that some form of self- 

 recording electrometer was needed. I believe that by means of self- 

 recording instruments tlie subject of atmospheric electricity can be 

 most advantageously studied. The main purpose in these experiments 

 was to show that it is possible to get some knowledge of the electrical 

 condition of the air at a distance from the ground, with the imperfect 

 means now at our command. 



The one point of striking interest in these experiments is the ob- 

 taining evidence of this high electrical potential in a sky free from 

 clouds. It will perhaps afford an argument against the necessity 

 of considering condensation in explaining the origin of atmospheric 

 electricity. 



It may still be questioned whether these experiments prove that the 

 potential of the air is positive, and increases steadily with increase in 

 elevation. The effects observed may possibly be due to the friction of 

 the air against the tinfoiled kite. My own opinion inclines to the 

 former belief. Questions of this nature, however, can be definitely 

 settled by the results of many and long observations. To accomplish 

 these it is indispensable that a self-recording electrometer be devised, 

 so that the records obtained may be directly comparable with the 

 continuous records of the more prominent meteorological conditions. 



I am much indebted to Mr. A. Lawrence Rotch, of the Observatory 

 at Blue Hill, for assistance in carrying on these experiments. 



Cambridge, Mass. 



