Scott's Last Expedition Part 23

Later. The Hut Point record of freezing is:

Night 24th-25th. Ice forming mid-day 25th, opened with leads.

26th. Ice all out, sound apparently open.

27th. Strait apparently freezing.

Early 28th. Ice over whole Strait.

29th. All ice gone.

30th. Freezing over.

May 4th. Broad lead opened along land to Castle Rock, 300 to 400 yds. wide.

Party intended to start on 11th, if weather fine.

Very fine display of aurora to-night, one of the brightest I have ever seen--over Erebus; it is conceded that a red tinge is seen after the movement of light.

_Sat.u.r.day, April_ 29.--Went to Inaccessible Island with Wilson. The agglomerates, kenytes, and lavas are much the same as those at Cape Evans. The Island is 540 ft. high, and it is a steep climb to reach the summit over very loose sand and boulders. From the summit one has an excellent view of our surroundings and the ice in the Strait, which seemed to extend far beyond Cape Royds, but had some ominous cracks beyond the Island.

We climbed round the ice foot after descending the hill and found it much broken up on the south side; the sea spray had washed far up on it.

It is curious to find that all the heavy seas come from the south and that it is from this direction that protection is most needed.

There is some curious weathering on the ice blocks on the N. side; also the snow drifts show interesting dirt bands. The island had a good sprinkling of snow, which will all be gone, I expect, to-night. For as we reached the summit we saw a storm approaching from the south; it had blotted out the Bluff, and we watched it covering Black Island, then Hut Point and Castle Rock. By the time we started homeward it was upon us, making a harsh chatter as it struck the high rocks and sweeping along the drift on the floe.

The blow seems to have pa.s.sed over to-night and the sky is clear again, but I much fear the ice has gone out in the Strait. There is an ominous black look to the westward.

_Sunday, April_ 30.--As I feared last night, the morning light revealed the havoc made in the ice by yesterday's gale. From Wind Vane Hill (66 feet) it appeared that the Strait had not opened beyond the island, but after church I went up the Ramp with Wilson and steadily climbed over the Glacier ice to a height of about 650 feet. From this elevation one could see that a broad belt of sea ice had been pushed bodily to seaward, and it was evident that last night the whole stretch of water from Hut Point to Turtle Island must have been open--so that our poor people at Hut Point are just where they were.

The only comfort is that the Strait is already frozen again; but what is to happen if every blow clears the sea like this?

Had an interesting walk. One can go at least a mile up the glacier slope before coming to creva.s.ses, and it does not appear that these would be serious for a good way farther. The view is magnificent, and on a clear day like this, one still enjoys some hours of daylight, or rather twilight, when it is possible to see everything clearly.

Have had talks of the curious cones which are such a feature of the Ramp--they are certainly partly produced by ice and partly by weathering. The ponds and various forms of ice grains interest us.

To-night have been naming all the small land features of our vicinity.

_Tuesday, May_ 2.--It was calm yesterday. A balloon was sent up in the morning, but only reached a mile in height before the instrument was detached (by slow match).

In the afternoon went out with Bowers and his pony to pick up instrument, which was close to the sh.o.r.e in the South Bay. Went on past Inaccessible Island. The ice outside the bergs has grown very thick, 14 inches or more, but there were freshly frozen pools beyond the Island.

In the evening Wilson opened the lecture series with a paper on 'Antarctic Flying Birds.' Considering the limits of the subject the discussion was interesting. The most attractive point raised was that of pigmentation. Does the absence of pigment suggest absence of reserve energy? Does it increase the insulating properties of the hair or feathers? Or does the animal clothed in white radiate less of his internal heat? The most interesting example of Polar colouring here is the increased proportion of albinos amongst the giant petrels found in high lat.i.tudes.

To-day have had our first game of football; a hara.s.sing southerly wind sprang up, which helped my own side to the extent of three goals.

This same wind came with a clear sky and jumped up and down in force throughout the afternoon, but has died away to-night. In the afternoon I saw an ominous lead outside the Island which appeared to extend a long way south. I'm much afraid it may go across our pony track from Hut Point. I am getting anxious to have the hut party back, and begin to wonder if the ice to the south will ever hold in permanently now that the Glacier Tongue has gone.

_Wednesday, May_ 3.--Another calm day, very beautiful and clear. Wilson and Bowers took our few dogs for a run in a sledge. Walked myself out over ice in North Bay--there are a good many cracks and pressures with varying thickness of ice, showing how tide and wind s.h.i.+ft the thin sheets--the newest leads held young ice of 4 inches.

The temperature remains high, the lowest yesterday -13; it should be much lower with such calm weather and clear skies. A strange fact is now very commonly noticed: in calm weather there is usually a difference of 4 or 5 between the temperature at the hut and that on Wind Vane Hill (64 feet), the latter being the higher. This shows an inverted temperature.

As I returned from my walk the southern sky seemed to grow darker, and later stratus cloud was undoubtedly spreading up from that direction--this at about 5 P.M. About 7 a moderate north wind sprang up. This seemed to indicate a southerly blow, and at about 9 the wind s.h.i.+fted to that quarter and blew gustily, 25 to 35 m.p.h. One cannot see the result on the Strait, but I fear it means that the ice has gone out again in places. The wind dropped as suddenly as it had arisen soon after midnight.

In the evening Simpson gave us his first meteorological lecture--the subject, 'Coronas, Halos, Rainbows, and Auroras.' He has a remarkable power of exposition and taught me more of these phenomena in the hour than I had learnt by all previous interested inquiries concerning them.

I note one or two points concerning each phenomenon.

_Corona_.--White to brown inside ring called Aureola--outside are sometimes seen two or three rings of prismatic light in addition. Caused by diffraction of light round drops of water or ice crystals; diameter of rings inversely proportionate to size of drops or crystals--mixed sizes of ditto causes aureola without rings.

_Halos_.--Caused by refraction and reflection through and from ice crystals. In this connection the hexagonal, tetrahedonal type of crystallisation is first to be noted; then the infinite number of forms in which this can be modified together with result of fractures: two forms predominate, the plate and the needle; these forms falling through air a.s.sume definite position--the plate falls horizontally swaying to and fro, the needle turns rapidly about its longer axis, which remains horizontal. Simpson showed excellent experiments to ill.u.s.trate; consideration of these facts and refraction of light striking crystals clearly leads to explanation of various complicated halo phenomena such as recorded and such as seen by us on the Great Barrier, and draws attention to the critical refraction angles of 32 and 46, the radius of inner and outer rings, the position of mock suns, contra suns, zenith circles, &c.

Further measurements are needed; for instance of streamers from mock suns and examination of ice crystals. (Record of ice crystals seen on Barrier Surface.)

_Rainbows_.--Caused by reflection and refraction from and through _drops of water_--colours vary with size of drops, the smaller the drop the lighter the colours and nearer to the violet end of the spectrum--hence white rainbow as seen on the Barrier, very small drops.

Double Bows--diameters must be 84 and 100--again from laws of refraction--colours: inner, red outside; outer, red inside--i.e. reds come together.

Wanted to see more rainbows on Barrier. In this connection a good rainbow was seen to N.W. in February from winter quarters. Reports should note colours and relative width of bands of colour.

_Iridescent Clouds_.--Not yet understood; observations required, especially angular distance from the sun.

_Auroras_.--Clearly most frequent and intense in years of maximum sun spots; this argues connection with the sun.

Points noticed requiring confirmation:

Arch: centre of arch in magnetic meridian.

Shafts: take direction of dipping needle.

Bands and Curtains with convolutions--not understood.

Corona: shafts meeting to form.

Notes required on movement and direction of movement--colours seen--supposed red and possibly green rays preceding or accompanying movement. Auroras are sometimes accompanied by magnetic storms, but not always, and vice versa--in general significant signs of some connection--possible common dependents on a third factor. The phenomenon further connects itself in form with lines of magnetic force about the earth.

(Curious apparent connection between spectrum of aurora and that of a heavy gas, 'argon.' May be coincidence.)

Two theories enunciated:

_Arrhenius_.--Bombardments of minute charged particles from the sun gathered into the magnetic field of the earth.

_Birkeland_.--Bombardment of free negative electrons gathered into the magnetic field of the earth.

It is experimentally shown that minute drops of water are deflected by light.

It is experimentally shown that ions are given off by dried calcium, which the sun contains.

Professor Stormer has collected much material showing connection of the phenomenon with lines of magnetic force.

_Thursday, May_ 4.--From the small height of Wind Vane Hill (64 feet) it was impossible to say if the ice in the Strait had been out after yesterday's wind. The sea was frozen, but after twelve hours' calm it would be in any case. The dark appearance of the ice is noticeable, but this has been the case of late since the light is poor; little snow has fallen or drifted and the ice flowers are very spa.r.s.e and scattered.