Under what circumstances this took place is shown by the following abstract of the observations of temperature at Pitlekaj from the 13th June to the 18th July, 1879:—
Max Min Mean Max Min Mean
June 13 +3.6° -8.0° -1.95° July 1 +0.8° -0.6° +0.07°
14 +2.6 +0.2 +1.47 2 +1.1 -1.0 +0.40
15 +3.1 +1.7 +2.28 3 +5.0 +1.0 +2.28
16 +1.6 -0.6 +0.90 4 +3.8 +1.4 +2.68
17 +3.0 +0.2 +1.22 5 +5.2 +2.0 +3.60
18 +2.4 -0.6 +1.23 6 +8.6 +1.0 +2.28
19 +3.6 +1.4 +2.43 7 +5.0 +1.4 +2.68
20 +3.5 +1.7 +2.50 8 +8.6 +0.6 +4.82
21 +2.6 +1.5 +2.07 9 +1.8 +0.4 +0.97
22 +3.0 +1.5 +2.28 10 +1.4 +0.5 +0.90
23 +4.1 +1.8 +3.00 11 +1.4 +0.6 +1.00
24 +6.8 +0.9 +3.18 12 +9.0 +0.5 +4.73
25 +4.4 +0.4 +2.30 13 +6.5 +3.7 +5.03
26 +3.8 +0.6 +1.77 14 +5.4 +1.8 +3.68
27 +1.4 +0.7 +1.02 15 +1.6 +0.6 +1.13
28 +2.1 +0.2 +0.92 16 +3.0 +0.6 +1.52
29 +0.9 -1.0 +0.12 17 +11.5 +8.8 +7.80
30 +1.0 -1.8 -0.27 18 +9.2 +6.2 +7.52
The figures in the maximum column, it will be seen, are by no means very high. That the enormous covering of snow, which the north winds had heaped on the beach, could disappear so rapidly notwithstanding this low temperature probably depends on this, that a large portion of the heat which the solar rays bring with them acts directly in melting the snow without sun-warmed air being used as an intermediate agent or heat-carrier, partly also on the circumstance that the winds prevailing in spring come from the sea to the southward, and before they reach the north coast pass over considerable mountain heights in the interior of the country. They have therefore the nature of föhn winds, that is to say, the whole mass of air, which the wind carries with it, is heated, and its relative humidity is slight, because a large portion of the water which it originally contained has been condensed in passing over the mountain heights. Accordingly when the dry föhn winds prevail, a considerable evaporation of the snow takes place. The slight content of watery vapour in the atmosphere diminishes its power of absorbing the solar heat, and instead increases that portion of it which is found remaining when the sun's rays penetrate to the snowdrifts, and there conduce, not to raise the temperature, but to convert the snow into water. [261]
The aurora is, as is well-known, a phenomenon at the same time cosmic and terrestrial, which on the one hand is confined within the atmosphere of our globe and stands in close connection with terrestrial magnetism, and on the other side is dependent on certain changes in the envelope of the sun, the nature of which is as yet little known, and which are indicated by the formation of spots on the sun; the distinguished Dutch physicist, VON BAUMHAUER, has even placed the occurrence of the aurora in connection with cosmic substances which fall in the form of dust from the interstellar spaces to the surface of the earth. Thus splendid natural phenomenon besides plays, though unjustifiably, a great rôle in imaginative sketches of winter life in the high north, and it is in the popular idea so connected with the ice and snow of the Polar lands, that most of the readers of sketches of Arctic travel would certainly consider it an indefensible omission if the author did not give an account of the aurora as seen from his winter station. The scientific man indeed knows that this neglect has, in most cases, been occasioned by the great infrequency of the strongly luminous aurora just in the Franklin archipelago on the north coast of America, where most of the Arctic winterings of this century have taken place, but scarcely any journey of exploration has at all events been undertaken to the uninhabited regions of the high north, which has not in its working plan included the collection of new contributions towards dealing up the true nature of the aurora and its position in the heavens. But the scientific results have seldom corresponded to the expectations which had been entertained. Of purely Arctic expeditions, so far as I know, only two, the Austrian-Hungarian to Franz Josef Land (1872-74) and the Swedish to Mussel Bay (1872-73), have returned with full and instructive lists of auroras[262] Ross, PARRY, KANE, McCLINTOCK, HAYES, NARES, and others, have on the other hand only had opportunities of registering single auroras; the phenomenon in the case of their winterings has not formed any distinctive trait of the Polar winter night. It was the less to be expected that the Vega expedition would form an exception in this respect, as its voyage happened during one of the years of which we knew beforehand that it would be a minimum aurora year. It was just this circumstance, however, which permitted me to study, in a region admirably suited for the purpose, a portion of this natural phenomenon under uncommonly favourable circumstances. For the luminous arcs, which even in Scandinavia generally form starting-points for the radiant auroras, have here exhibited themselves undreamed by the more splendid forms of the aurora I have thus, undisturbed by subsidiary phenomena, been able to devote myself to the collection of contributions towards the ascertaining of the position of these luminous arcs, and I believe that I have in this way come to some very remarkable conclusions, which have been developed in detail in a separate paper printed in The Scientific Work of the Vega Expedition (Part I. p. 400). Here space permits me only to make the following statement
The appearance of the aurora at Behring's Straits in 1878-79 is shown in the accompanying woodcuts. We never saw here the magnificent bands or draperies of rays which we are so accustomed to in Scandinavia, but only halo-like luminous arcs, which hour after hour, day after day, were unaltered in position. When the sky was not clouded over and the faint light of the aurora was not dimmed by the rays of the sun or the full moon, these arcs commonly began to show themselves between eight and nine o'clock P.M., and were then seen without interruption during midwinter till six, and farther on in the year to three o'clock in the morning. It follows from this that the aurora even during a minimum year is a permanent natural phenomenon. The nearly unalterable position of the arcs has further rendered possible a number of measurements of its
DOUBLE AURORA ARCS SEEN 20TH MARCH 1879, AT 9.30 P.M.
ELLIPTIC AURORA SEEN 21ST MARCH, 1879, AT 2.15 A.M.