Dr. Everett on Atmospheric Electricity. 



543 



December 5. — Dr. William Allen Miller, Treasurer and Vice-Presi- 

 dent, in the Chair. 

 The following communication was read : — 



" Results of Observations of Atmospheric Electricity at Kew Ob- 

 servatory, and at Windsor, Nova Scotia." By Joseph D. Everett, 

 D.C.L., F.R.S.E., Assistant to the Professor of Mathematics in the 

 University of Glasgow. 



The paper commences with an account of the concluding observa- 

 tions taken by the author at Windsor, N.S., of which the previous por- 

 tion has already been published in the ' Proceedings/ vols. xii. & xiv. 



It then goes onto describe the self-recording apparatus employed 

 at Kew Observatory for the observation of atmospheric electricity, 

 and the method of procedure employed in measuring and reducing 

 the curves thus obtained, this portion of the work having been per- 

 formed in the Physical Laboratory of the University of Glasgow. 



Tables are given showing the mean hourly values of the electrical 

 potential for each month, and the mean monthly values are hence 

 derived. These values for Kew are compared with the corresponding 

 values for Windsor, N.S., and remarkable differences are shown to 

 exist between the curves, both diurnal and annual, for the two places. 



The hourly means at Kew for the mean of the year are represented 

 by the following numbers : — 



3 h h jh 2 h 



91 1*96 1-92 1-93 



3 h 9 h 10 h ll h 



96 2-93 274 2'42 



7 h 18 h 19 h 20 h 



52 1-64 1-96 2-26 



These numbers indicate a principal maximum between S h and 9 h , 

 and a secondary maximum between 20 h and 21 h . At Windsor, on 

 the other hand, the mean potential about 9 h was in every month, 

 without exception, less than at the other principal times of obser- 

 vation, viz. about 21 h and 14 h . 



The following Table shows the ratio of the mean monthly to the 

 mean annual potential for the whole series of observations at both 

 places : — 



Kew. 



23 h 



h 



l h 



2 h 



3 h 



4 b 



5 h 



6 h 



7 h 



1-91 



1-96 



1-92 



1-93 



1*95 



2-08 



2-29 



2-58 



2-86 



8 h 



9 h 



10 h 



ll h 



12 h 



13 h 



14 h 



15 h 



16 h 



2-96 



2-93 



274 



2'42 



2-12 



1-86 



1-68 



1-58 



1-54 



17 h 



18 h 



19 h 



20 h 



21 h 



22 h 









1-52 



1-64 



1-96 



2-26 



2-28 



2-13. 









June 



July 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



Jan. 



Feb. 



March 



April 



May 



1862 770 



„ 773 



„ -836 



„ '845 



„ -981 



„ 1-600 



„ 1-188 



1863 1-033 



„ 1-333 



1-160 



-920 



-672 



June 1863 



July » 



A«g. » 



Sept. „ 



Oct. „ 1 



Nov. „ 1 



Dec. „ 1 



Jan. 1864 1 



Feb. „ 1 



March „ 1 



April „ 



May „ 



•681 

 •643 

 •685 

 •854 

 •000 

 •390 

 •460 

 •226 

 •263 

 •375 

 •831 

 •549 



