The observations show that the pressure of the atmosphere is throughout low, the mean for the ten months being 29.07 inches (738.6 millimetres).  It is lower in winter than in summer, July having 28.86 inches (733.1 millimetres), and December 29.65 inches (753.3 millimetres), as the mean for the month, a difference of 20.2 millimetres.  The highest observation was 30.14 inches (765.7 millimetres) on December 9, and the lowest 28.02 inches (711.7 millimetres) on May 24, 1911; difference, 54 millimetres.

Air Temperature and Thermometers.

As has already been stated, minimum thermometers and mercury sling thermometers were wanting.  For the first six months only toluene sling thermometers were used.  Sling thermometers are short, narrow glass thermometers, with a strong loop at the top; before being read they are briskly swung round at the end of a string about half a yard long, or in a special apparatus for the purpose.  The swinging brings the thermometer in contact with a great volume of air, and it therefore gives the real temperature of the air more readily than if it were hanging quietly in the screen.

From October 1 a mercury thermometer was also placed in the screen, though only one divided to whole degrees; those divided to fifths of a degree would, of course, have given a surer reading.  But it is evident, nevertheless, that the toluene thermometers used are correct to less than half a degree (Centigrade), and even this difference may no doubt be explained by one thermometer being slung while the other was fixed.  The observations are, therefore, given without any corrections.  Only at the end of December was exclusive use made of mercury thermometers.  The maximum thermometers taken proved of so little use that they were soon discarded; the observations have not been included here.

It was due to a misunderstanding that mercury thermometers were not also used in the first half-year, during those periods when the temperature did not go below the freezing-point of mercury (-89deg.  C.).  But the toluene thermometers in use were old and good instruments, so that the observations for this period may also be regarded as perfectly reliable.  Of course, all the thermometers had been carefully examined at the Norwegian Meteorological Institute, and at Framheim the freezing-point was regularly tested in melting snow.

The results show that the winter on the Barrier was about 19.deg.  C. (21.6deg.  F.) colder than it usually is in McMurdo Sound, where the British expeditions winter.  The coldest month is August, with a mean temperature of -44.5deg.  C. (-48.1deg.  F.); on fourteen days during this month the temperature was below -50deg.  C. (-58deg.  F.).  The lowest temperature occurred on August 13:  -58.5deg.  C. (-73.3deg.  F.); the warmest day in that month had a temperature of -24deg.  C. (-11.2deg.  F.).

In October spring begins to approach, and in December the temperature culminates with a mean for the month of -6.6deg.  C. (+2O.ldeg.  F.), and a highest maximum temperature of -0.2deg.  C. (+31.6deg.  F.).  The temperature was thus never above freezing-point, even in the warmest part of the summer.