Page:Polar Exploration - Bruce - 1911.djvu/237

Rh coronæ, and exhibiting bright flashes of all the prismatic colours, green and red being the more frequent and conspicuous; this aurora had much motion, darting and quivering about the sky in rapid flights, and in every direction."

Rather in contradiction to Buchan's statement, Ross records, on the 28th of March, that "at 10 p.m. a single flash of forked lightning was seen in the north-north-east and at the same time an arch of aurora extended across the zenith from the horizon west-north-west and east-south-east; it was then blowing a strong north-westerly gale." Again, "The Aurora appeared in great brilliancy during the night of the 30th." Buchan's statement is, however, generally speaking correct, this being another of those cases illustrating how impossible it is to draw hard-and-fast lines in nature.

The study of tides is an important part of Polar exploration, and their study in Antarctic Regions more generally useful than in the Arctic Regions, for in the Great Southern Ocean lie the original tides of the world.

"The Scotia results," says Sir George Darwin, "are very valuable as relating to the only ocean uninterrupted by land throughout the whole circumference of the globe," and they