.e. the difference of temperature between A and C being much less
than the adiabatic gradient.

In this condition there is a tendency to cool by radiation until
some critical layer, B, reaches its due point. A stratus cloud is
thus formed at B; from this moment A B continues to cool, but B C is
protected from radiating, whilst heated by radiation from snow and
possibly by release of latent heat due to cloud formation.

The condition now rapidly approaches unstable equilibrium, B C tending
to rise, A B to descend.

Owing to lack of sun heat the effect will be more rapid in south than
north and therefore the upset will commence first in the south. After
the first start the upset will rapidly spread north, bringing the
blizzard. The facts supporting the theory are the actual formation
of a stratus cloud before a blizzard, the snow and warm temperature
of the blizzard and its gusty nature.

It is a pretty starting-point, but, of course, there are weak spots.

Atkinson has found a trypanosome in the fish--it has been stained,
photographed and drawn--an interesting discovery having regard to
the few species that have been found. A trypanosome is the cause of
'sleeping sickness.'

The blizzard has continued all day with a good deal of drift. I went
for a walk, but the conditions were not inviting.

We have begun to consider details of next season's travelling
equipment. The crampons, repair of finnesko with sealskin, and an
idea for a double tent have been discussed to-day. P.O. Evans and
Lashly are delightfully intelligent in carrying out instructions.

_Sunday, June_ 11.--A fine clear morning, the moon now revolving well
aloft and with full face.

For exercise a run on ski to the South Bay in the morning and a dash
up the Ramp before dinner. Wind and drift arose in the middle of the
day, but it is now nearly calm again.

At our morning service Cherry-Garrard, good fellow, vamped the
accompaniment of two hymns; he received encouraging thanks and will
cope with all three hymns next Sunday.

Day by day news grows scant in this midwinter season; all events seem
to compress into a small record, yet a little reflection shows that
this is not the case. For instance I have had at least three important
discussions on weather and ice conditions to-day, concerning which
many notes might be made, and quite a number of small arrangements
have been made.

If a diary can be so inadequate here how difficult must be the task