Page:The Worst Journey in the World volume 2.djvu/329

552 Simpson, in his meteorological report, has little doubt that the temperatures met by the Polar Party were abnormal. The records "clearly bring to light the possibility of great cold at an extremely early period in the year within a comparatively few miles of an open sea where the temperatures were over 40 degrees higher." "It is quite impossible to believe that normally there is a difference of nearly 40 degrees in March between McMurdo Sound and the South of the Barrier." The temperatures recorded by other sledge parties in March 1912 and those recorded at Cape Evans form additional evidence, in Simpson's opinion, that the temperatures experienced by Scott were not such as might be expected during normal autumn weather.

Simpson's explanation is based upon the observations made in McMurdo Sound by sending up balloons with self-recording instruments attached. These showed that very rapid radiation takes place from the snow surface in winter, which cools the air in the immediate neighbourhood: a cold layer of air is thus formed near the ground, which may be many degrees colder than the air above it. It becomes, as it were, colder than it ought to be. This, however, can only happen during an absence of wind: when a wind blows the cold layer is swept away, the air is mixed and the temperature rises.

The absence of wind from the south noted by Scott was, in Simpson's opinion, the cause of the low temperatures met by Scott: the temperature was reduced ten degrees below normal at Cape Evans, and perhaps twenty degrees where Scott was.

The third question is that of food. It is this point which is most important to future explorers. It is a fact that the Polar Party failed to make their distance because they became weak, and that they became weak although they were eating their full ration or more than their full ration of food, save for a few days when they went short on the way down the Beardmore Glacier. The first man to weaken