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XI. Besults of Observations of Atmospheric Electricity at Kew Observatory , and at 
King's College , Windsor , Nova Scotia. By Joseph D. Everett, B.C.L., F.B.S.E. 
Communicated by Sir William Thomson, F.B.S. 
Eeceived October 14,- — Read December 5, 1867. 
My papers of June 18th, 1863 and January 12, 1865, contained a record of observations 
at Windsor, Nova Scotia, from October 1862 to the end of February 1864. From this 
latter date they were continued until August 8th of the same year, and 1 have now to 
report this concluding series, giving at the same time a summary of results derived from 
the whole of my observations. 
I have also to report, at the request of Sir William Thomson, the results of two 
years’ observations of atmospheric electricity taken at Kew Observatory with his self-re- 
cording apparatus, and reduced under his direction and under my own more immediate 
supervision at the Natural Philosophy Laboratory of the University of Glasgow. 
The concluding series of observations at Windsor were taken regularly at the three 
principal hours previously adopted, that is to say, about 9 A.M., 2 p.m., and 10 P.M., but 
very few were taken at other hours. The station electrometer alone was used, and the 
electricity was collected by burning-match. The glass fibre mounted in the electro- 
meter July 31, 1863, remained unchanged to the end of the observations, thus giving a 
full year’s observations with the same fibre. 
All the generalizations noticed in my former papers apply also to the concluding 
series, with the single exception that negative electricity was once observed under a clear 
sky. This phenomenon was observed at 10 p.m., July 15th, and as its exceptional cha- 
racter struck me at the time, it was carefully verified. The negative potential was equal 
in absolute amount to about half the average positive potential. The temperature was 
59°T, wet bulb 2°*7 below dry, barometer 30T0, no wind, sky perfectly clear, except a 
little cirrocumulus near the horizon. There was a faint trace of aurora overhead. The 
weather had been fine for several days, and continued so for several days after. 
The following Table, showing the mean hourly electrical potential in fine weather 
for each month in the concluding series, has been computed in the same manner as the 
corresponding Tables in my previous papers. The numbers in this Table are in units 
of “ Station Electrometer with third fibre.” 
MDCCCLXVIII. 
