low temperatures of the south polar summer, which are probably due to the great continental mass of ice around the south pole, are responsible for much of the difficulty of Antarctic exploration. The average annual temperatures have been in the vicinity of 10°-15°; and the minima of an ordinary Antarctic winter go down to—40°, and below, but so far no minima of the severest Siberian intensity have been noted. The British expedition on the Discovery recorded a minimum temperature of—67.7°, and also noted—40° in midsummer. The highest temperatures have varied between about 35° and 50°. It is likely that near the south pole will prove to be the coldest point on the earth's surface in the average for the year, and also that the lowest winter and summer temperatures in the southern hemisphere will be found in the immediate vicinity of the pole.
The polar zones have a permanent deficiency of precipitation (1510 inches, or less). The polar deserts of snow and ice are therefore deserts in more senses than one, although it is natural that these extended snow and ice fields should tend to give an exaggerated idea of the actual amount of snowfall. So far as exploration has yet gone into the highest northern latitudes, rain has been found to fall in summer, and it is doubtful whether there are any places in the world, near sealevel where all the precipitation comes in the form of snow. Perhaps the interior of the south polar continent may never have rain. The snow of the polar regions is characteristically fine and dry, and it has been pointed out that the snow huts of the Eskimos could not be built with our kind of snow. At low polar temperatures flakes of snow are not found, but precipitation is in the form of ice spicules.
The inner polar areas seem to be beyond the reach of the most frequent and most violent storms, and as most of the observations thus far obtained from the Antarctic come from the marginal zone of great storm activity, violent winds and wet, disagreeable weather, they do not show us the features of the actual south polar climate. Extraordinary records of storm and gale have been brought back from the far south and the far north. During the long, dreary winter night the temperature falls to very low readings. Snowstorms and gales alternate at irregular intervals with calmer spells of more extreme cold and clear skies. There is no really warm season. The summer is essentially only a modified winter, especially in the Antarctic. Yet the Arctic summer, with its long days, crisp, clean air and sunshine, has many attractive qualities, and we may fairly safely predict a considerable development of summer resorts within the Arctic circle for the pleasure-loving, wealthy and unoccupied persons of the north temperate zone.
Climate and Health.—We have now seen something of the climatic zones and of their characteristics. Let us turn for a few minutes to the question of climate and health—a subject which is surely of the greatest concern to man. From the earliest times people have sought in
