694 [June 18, 



21. For the sake of showing the variations of atmospheric electricity 

 from minute to minute, I subjoin all the observations taken on the 

 10th day of each month, from October to March. With the excep- 

 tion of the evening of February 10th, these are fair samples of 

 ordinary observations. I also subjoin the observations which were 

 taken on the 26th of November, as a specimen of very great and 

 rapid changes in atmospheric electricity. In all these instances the 

 electrical potential of the air is given in units of the electrometer 

 with which it was observed. The readings of dry and wet bulb are 

 also given without correction. (See Table I.) 



22. I also subjoin Tables of all the observations (or rather the 

 mean highest and lowest of each group) taken during rain, snow, 

 hail, sleet, and fog. These numbers are merely copied from the 

 complete Table of observations already given, and thus collected for 

 greater convenience of reference. (See Table II.) 



It will be observed that the electricity found is almost invariably 

 positive during snow. Out of 25 days on which observations were 

 taken during snow, there were 23 on which positive electricity only 

 was observed, on the remaining 2 days both positive and negative 

 being observed. 



Of 28 days on which observations were taken during rain, there 

 were 9 on which positive only was observed, 7 on which negative 

 only, and 1 2 on which both kinds were observed. 



There were only 2 days on which observations were taken during 

 hail, and on both of these both kinds of electricity were observed, 

 but with a great preponderance of negative. 



On 2 days observations were taken during sleet. In one instance 

 the electricity found was positive, and in the other it changed from 

 weak positive to weak negative. 



On 5 days observations have been taken during fog, and the 

 electricity found was always positive, generally much above the 

 average strength. 



Light rain, unless accompanied by mist, has never shown strong 

 electricity ; but heavy rain, as also moderate rain with mist, is in the 

 majority of instances marked by very strong electricity. 



I have not been able to ascertain, by inspection, any connexion 

 between the direction of the wind during rain and the accompanying 

 electricity. 



