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.[353]

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 was the biggest and
heaviest man in the expedition: "the man whom we had least expected to
fail."

The rations were of two kinds. The Barrier (B) ration was that which was
used on the Barrier during the outward journey towards the Pole. The
Summit (S) ration was the result of our experiments on the Winter
Journey. I expect it is the best ration which has been used to date, and
consisted of biscuits 16, pemmican 12, butter 2, cocoa 0.57, sugar 3 and
tea 0.86 ounces; total 34.43 ounces daily per man.

The twelve men who went forward started this S ration at the foot of the
Beardmore, and it was this ration which was left in all depots to see
them home. It was much more s