Page:Popular Science Monthly Volume 50.djvu/343

Rh into Greenland, or to a mountain chain which is far removed from what is assumed to be the continental border.

The ablest discussion of the physical and geographical relations of Antarctica is furnished by the late Dr. Petermann in the Mittheilungen of 1863. He there argues strongly in favor of at least a partially open South Polar Sea, whose position is located central to the great ice masses which radiate out from it, and in



seasons of disruption—the months of November to April, the southern summer—press northward as the great Antarctic Barrier, the circle of pack ice which at varying latitudes has been the bar to passage of the different exploring expeditions. The special reasons advanced for this construction of the antarctic region are essentially two: (1) The comparatively low summer temperature of the south as compared with that of the arctic regions, an indication of oceanic rather than of continental conditions; and (2) the irregularity or instability of the pack ice, the front varying in