258 SCOTT'S LAST EXPEDITION [May 
Corona : shafts meeting to form. 
Notes required on movement and direction of move- 
ment — colours seen — supposed red and possibly green 
rays preceding or accompanying movement. Auroras 
are sometimes accompanied by magnetic storms, but not 
always, and vice versa — in general significant signs of some 
connection — possible common dependants on a third factor. 
The phenomenon further connects itself in form with lines 
of magnetic force about the earth. 
(Curious apparent connection between spectrum of 
aurora and that of a heavy gas, ' argon. 5 May be 
coincidence.) 
Two theories enunciated : 
Arrhenius. — Bombardments of minute charged particles 
from the sun gathered into the magnetic field of the earth. 
Birkeland. — Bombardment of free negative electrons 
gathered into the magnetic field of the earth. 
It is experimentally shown that minute drops of water 
are deflected by light. 
It is experimentally shown that ions are given off by 
dried calcium, which the sun contains. 
Professor Stormer has collected much material showing 
connection of the phenomenon with lines of magnetic 
force. 
Thursday, May 4. — From the small height of Wind 
Vane Hill (64 feet) it was impossible to say if the ice in 
the Strait had been out after yesterday's wind. The sea 
was frozen, but after twelve hours' calm it would be in 
any case. The dark appearance of the ice is noticeable, 
but this has been the case of late since the light is poor ; 
