GU 



Electrification of the Air near the Zambesi Falls. 



that the comparative values had to be obtained by noting the 

 time required by the leaves to reach the maximum. 



At 1000 paces the time was 50 sees. 

 „ 1100 „ „ 36 „ 



» l-'OO ,, „ 30 „ 



„ 1300 „ „ 25 „ 



At this point the indication became rather erratic owing to 

 the spray being carried by the wind towards the instrument. 

 When the spray was encountered on the confines of the 

 " Rain Forest," the electroscope was charged to a maximum 

 in a second or two, in some cases in even less, so that the 

 leaves were continuously moving up and down. 



Table II. 

 Potential Gradient at Different Distances from Fall. 



Distance from Falls 

 in paces. 



Height of 

 Electroscope 

 above ground. 



Charge. 



1 

 Potential 

 Gradient. 

 Volts per metre. 



500 



20 cms. 

 20 „ 

 20 „ 

 50 „ 

 50 „ 

 50 „ 

 50 ., 



- 



5,000 



3.500 

 * 



2,400 

 1 .700 

 1.390 

 1,000 



# 



500 



425 



300 



250 



200 



100 



75 



75 



50 



50 







(500 



7n0 



800 



901) 



1.000 



1,100 



1.200 



50 ,. 



— 



1.300 



50 „ 



50 ,. - 

 100 ., 

 160 „ 

 160 .. 



1,400 



1,500 



1,600 



1,700 



1,800 



160 „ 





1,900 



2,000 



160 ,. 

 160 „ 

 160 ., 

 160 „ 

 ICO ., 

 160 ,. 

 160 ,. 







2.100 



2,200 



2,300 



2,400 



2,500 





* Values uncertain. 



At the bottom of the gorge, but screened from the f;ills 

 by a bend, the electroscope diverged to a maximum in 

 15 seconds, but if the spray got carried by the wind towards 

 the instrument, it was at once charged to a maximum. At 

 Livingstone, eight miles from the falls, the potential had 

 fallen to a low value, and always, during the short time 

 spent there, was positive. On the way to Livingstone some 



