Page:Scott's Last Expedition, Volume 1.djvu/404

258 Corona: shafts meeting to form.

Notes required on movement and direction of movement—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.’ 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 Störmer 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;