OPTICAL PHENOMENA. 525 



The appearances exhibited by the aurora are so various as to render it impossible to 

 comprehend every particular in a description that must be necessarily brief and general. 

 A cloud, or haze, is commonly seen in the northern region of the heavens, but often 

 bearing towards the east or west, assuming the form of an arc, seldom attaining a greater 

 altitude than 40, but varying in extent from 5 to 100. The upper edge of the cloud 

 is luminous, sometimes brilliant, and irregular. The lower part is frequently dark and 

 thick, with the clear sky appearing between it and the horizon. Streams of light shoot 

 up in columnar forms from the upper part of the cloud, now extending but a few degrees, 

 then as far as the zenith, and even beyond it. Instances occur in which the whole 

 hemisphere is covered with these coruscations ; but the brilliancy is the greatest, and the 

 light the strongest, in the north, near the main body of the meteor. The streamers have 

 in general a tremulous motion, and when close together present the appearance of waves, 

 or sheets of light, following each other in rapid succession. But no rule obtains with 

 reference to these streaks, which have acquired the name of " the merry dancers," from 

 their volatility, becoming more quick in their motions in stormy weather, as if sym- 

 pathising with the wildness of the blast. Such is the extraordinary aspect they present, 

 that it is not surprising the rude Indians should gaze upon them as the spirits of their 

 fathers roaming through the land of souls. They are variously white, pale red, or of a 

 deep blood colour, and sometimes the appearance of the whole rainbow as to hue is 

 presented. When several streamers emerging from different points unite at the zenith, 

 a small and dense meteor is formed, which seems to burn with greater violence than the 

 separate parts, and glows with a green, blue, or purple light. The display is over some- 

 times in a few minutes, or continues for hours, or through the whole night, and appears 

 for several nights in succession. Captain Beechey remarked a sudden illumination to 

 occur at one extremity of the auroral arch, the light passing along the belt with a tremulous 

 hesitating movement towards the opposite end, exhibiting the colours of the rainbow ; and 

 as an illustration of this appearance, he refers to that presented by the rays of some 

 molluscous animals in motion. Captain Parry notices the same effect as a common one 

 with the aurora, and compares it, as far as its motion is concerned, to a person holding a 

 long riband by one end, and giving it an undulatory movement through its whole length, 

 though its general position remains the same. Captain Sabine likewise speaks of the 

 arch being bent into convolutions, resembling those of a snake in motion. Both Parry, 

 Franklin, and Beechey agree in the observation that no streamers were ever noticed 

 shooting downwards from the arch. 



The preceding statement refers to aurora in high northern latitudes, where the full 

 magnificence of the phenomenon is displayed. It forms a fine compensation for the long 

 and dreary night to which these regions are subject, the gay and varying aspect of the 

 heavens contrasting refreshingly with the repelling and monotonous appearance of the 

 earth. We have already stated that the direction in which the aurora generally makes 

 its first appearance, or the quarter in which the arch formed by this meteor is usually 

 seen, is to the northward. But this does not hold good of very high latitudes, for by the 

 expeditions which have wintered in the ice, it was almost always seen to the southward ; 

 while by Captain Beechey, in the Blossom, in Kotzerne Sound, 250 miles to the southward 

 of the ice, it was always observed in a northern direction. It would appear, therefore, 

 from this fact, that the margin of the region of packed ice is most favourable to the 

 production of the meteor. The reports of the Greenland ships confirm this idea ; for, 

 according to their concurrent testimony, the meteoric display has a more brilliant aspect 

 to vessels passing near the situation of the compact ice, than to others entered far within 

 it. Instances, however, are not wanting, of the aurora appearing to the south of the 

 zenith in comparatively low latitudes. Lieutenant Chappell, in his voyage to Hudson's 



