234 



ATMOSPHERIC ELECTRICITY. 



Time 



Potential 

 Gradient. 



11-45 29 



11.57 29 



11'. o noon .... 2^ 



12. 5 p m 2S 



12.50 28 



3-50 28 



4.10 28 



540 31 



Potential 

 Time. Gradient. 



6.30 35 



7-30 40 



8. o 56 



9- c 70 



9-50 78 



10. 101 



10.20 106 



11. o 106 



Potential 

 Time. Gradient. 



II. TO 77 



11-30 57 



11.40 40 



11-45 39 



11-55 32 



12. o 32 



Fisf. I. 



.300 



250 



200 



150 



t: 100 



50 



a.m. 



10 3 pm. 



Time in Hours 



1 a 



In July, 1910, observations were made at Victoria Falls, 

 Kesi, Wankie, Pasipas, Bnlawayo, Westacre, Matoppos, Maha- 

 lapye, Artesia, Lobatsi, Mafeking, Vryburg, Taungs, Potchef- 

 stroom, Johannesburg. The complete set of observations at the 

 Falls has been already referred to, but it may here be noted that 

 at a distance of two miles from the Falls their influence was 

 almost negligible, while further away the ordinary electrical state 

 existed. Within a mile of the Falls, the potential gradient was 

 at times of the order of over 600 volts per metre, and negative, 

 while at Livingstone it did not exceed 60 volts, and was positive. 

 On the river albove the Falls, the value was zero for some 

 distance; and at seven and a half miles, it was about 100 volts 

 and positive. 



