39 



other clouds in the neighbourhood, the phenomena might be 

 complicated to any extent. 



And if, further, the motion of the sun is taken into 

 account ; as the conductor S moves round E the charges in D 

 and E would vary, accordingly as they were more or less 

 between S and E and directly under the induction of S ; 

 i.e., the charge in a cloud would appear to change owing to 

 the motion of the sun ; thus a cloud that appeared neutral 

 at midday would, if it did not receive or give off any 

 electricity, become charged positively in the evening. 



With regard to the independent motion of the clouds, 

 there are several causes which would effect it. For instance, 

 a cloud whether it appeared on the earth to be negatively 

 or positively charged would always tend to follow the sun, 

 though it is possible this tendency might be very slight. 

 Again, one cloud would attract or repel another, according 

 as they were charged with the opposite or the same electri- 

 cities ; And in the same way a cloud would be attracted or 

 repelled by a hill, according to the nature of their respective 

 charges. 



Such, then, would be some of the more apparent pheno- 

 mena under the assumed conditions. So far as I can see they 

 agree well with the general appearance of what actually 

 takes place, but as I have previously said, the laws relating 

 to thunder storms are not sufficiently known to warrant 

 me in doing more than suggesting this as a probable 

 explanation. 



In these remarks I have said nothing whatever about 

 what is called atmospheric electricity, or the apparent 

 increase of positive tension as we proceed away from the 

 surface of the earth. I do not think that this has much to 

 do with thunder storms. If the law is established it seems 



