320 Proceedings of the Royal Society of Edinburgh. [Sess. 
of strong winds. The position of the return current is clearly seen, and its 
velocity is greatest in the neighbourhood of the temperature discontinuity. 
This relation between the return current and the discontinuity is 
19” August 1909 
50 feet 
v = 12 -s c ms. 
W 
W 
lOOfeet 
V=6-$c/ns. 
• • 
180 feet 
v= 3 i cms . 
W 
s 
Fig. 8 
