138 



On Ozone. 



The electric tension for the seasons is as follows — 



QUARTER. 



Spring 

 Summer 

 Autumn 

 Winter 



Year 



MEAN TENSION. 



Positive Electricity. 

 Parts. 

 3-12 

 2-64 

 2-89 

 3-40 



3-01 



MEAN NO. OF REGISTRATIONS. 



Negative Elect. 



159 



242 



117 



71 



No Elect. 



186 

 248 

 153 

 148 



735 



The positive tension, being the normal state of atmo- 

 spheric electricity, assumes its smallest value in the months 

 of Februaiy and November, and its highest in the months 

 of June and September, the range in the monthly mean 

 amounting to 1'17 parts of division. 



The electric tension is chiefly negative during hot winds, 

 when clouds of dust are floating in the air, and during heavy 

 rain ; in the latter case the negative tension is frequently 

 so great that vivid sparks may be obtained fi^om the 

 instrument. 



The collation of the observations on the tension of positive 

 atmospheric electricity gives the following results with 

 regard to the means for the even hours throughout the year, 

 showing a daily amplitude of two to three parts of division, 

 the turning points of the same being at 8 h. a.m. and 8 h. 

 p.m. 



Midnight 



297 



Noon 



.. 213 



2h. a.m. 



. 2-54 



2 h. p.m. 



., ^-72 



4h. „ 



2-64 



4h. „ 



1-92 



6h. „ 



. 3-41 



6h. „ 



.. 3-03 



8h. „ 



. 4-17 



8h. „ 



3-52 



lOh „ 



. 2-84 



10 h. „ 



3-36 



