NORTHERN LIGHTS. 



derstood as referring to magnetic latitude, meas- 

 ured from the magnetic pole. In Iceland, Green- 

 land, and Newfoundland, on the banks of the 

 Slave lake, and at Fort Enterprise (in North 

 Canada), the Aurora is lighted up, at certain 

 seasons, almost every night, and with its shift- 

 ing, shivering rays, performs its " merry dance" 

 through the sky, as the natives of the Shetland 

 Islands term it('**). Whilst in Italy the north- 

 ern light is a great rarity, it is seen with ex- 

 treme frequency in the latitude of Philadelphia 

 (39° 57' N. L.), in consequence of the southern 

 position of the American magnetic pole. But in 

 the districts of the new continent, and also of 

 the shores of Siberia, which are remarkable for 

 the frequency of the phenomenon, there occur 

 what may be called especial regions of the 

 northern lights — longitudinal zones in which 

 they are peculiarly splendid(^**.) Local influ- 

 ences are, consequently, not to be overlooked. 

 Wrangel observed their brilliancy decline as he 

 left the shores of the icy sea, about Nijne-Ko- 

 lymsk, behind him. The experience of the 

 Northern Polar Expedition seems to indicate 

 that the evolution of light is not greater in the 

 immediate vicinity of the magnetic pole than it 

 is at some distance from this spot. 



What we know of the altitude of the northern 

 light is based on measurements, which, by reason 

 of the incessant oscillations of the luminous 

 rays, and the consequent uncertainty of the 

 parallactic angle, cannot be greatly depended on. 

 The conclusions come to (not to speak of older 

 estimates) vary between several miles and three 

 or four thousand feet("^). It is not improbable 

 that the northern light is at very different dis- 

 tances at different times. The latest observers 

 are disposed to connect the phenomenon, not 

 with the outer limits of the atmosphere, but 

 with the region of the clouds itself; they even 

 believe that the northern streamers may be 

 moved by winds and currents of air, if the 

 luminous phenomenon, by which alone the ex- 

 istence of electro-magnetic emanations becomes 

 obvious to us, be actually connected with mate- 

 rial collections of vesicular vapour, or, to speak 

 more correctly, penetrates these collections, 

 darting over from one vesicle to another. Cap- 

 tain Franklin saw a streaming Aurora on Bear 

 lake, which he believed illuminated the under 

 side of the stratum of cloud ; whilst Kendal, 

 who had the watch through the whole of the 

 night, and never lost the heavens for a minute 

 from his sight, at the distance of but 4^ geo- 

 graphical miles, observed no luminous phe- 

 nomenon whatsoever. The statement, repeat- 

 ed several times of late, to the effect that 

 streamers of the northern light have been ob- 

 served close to the ground, and between the 

 observer and a neighbouring height, is one of 

 those points, which, like lightning and the fall 

 of fire-balls, is exposed to the manifold dangers 

 of optical deception. 



Whether or not the magnetic storm, of which 

 we have just quoted a remarkable example 

 of local circumscription within very narrow 

 bounds, have the noise, besides the light, in 

 common with the electrical storm, is now ren- 

 dered extremely doubtful, since the testimony 

 of the Greenland sledgers, and the Siberian 

 fox-hunters, is no longer taken unconditionally. 

 The northern lights have become more silent 



since they have been examined more carefully 

 with the eye and the ear. Parry, Franklin and 

 Richardson, near the north pole ; Thienemann, 

 in Iceland ; Gieseke, in Greenland ; Lottin and 

 Bravais, at the North Cape ; Wrangel and An- 

 jou, on the shores of the icy sea, have, alto- 

 gether, looked at thousands of northern lights, 

 yet never heard any noises. If this negative 

 testimony be not admitted against two positive 

 witnesses, Hearne, at the mouth of the Copper- 

 mine river, and Henderson, in Iceland, it must 

 still be remembered that Hood heard the same 

 noises — as of musket balls shaken rapidly to- 

 gether, and slight cracklings, during the occur- 

 rence of the northern lights, indeed, but also 

 on the following day, when there was no Au- 

 rora in the heavens ; and then it must not be 

 forgotten, that Wrangel and Gieseke were firm- 

 ly convinced that the noises heard were owing 

 to contractions of the ice and crust of snow, 

 in consequence of a sudden cooling of the air. 

 The belief in a crapkling noise did not take its 

 origin among the people, but with learned trav- 

 ellers, and in this way : the flashing of elec- 

 tricity in attenuated atmospheres having been 

 known from an early period, the northern light 

 was forthwith declared to be an effect of at- 

 mospheric electricity, and then the noises were 

 heard that ought to have been heard. Recent 

 experiments with the most delicate electrome- 

 ters, however, contrary to all expectation, have 

 hitherto given merely negative results ; the 

 state of the aerial electricity has not been found 

 altered during the prevalence of the most brill- 

 iant Auroras. 



All the three manifestations of force of the 

 terrestrial magnetism — Declination, Inclina- 

 tion, and Intensity, on the contrary, are affect- 

 ed at once by the northern lights. In one and 

 the same night, and from hour to hour, the Au- 

 rora affects the same end of the needle differ- 

 ently, now attracting it, now repelling it. The 

 assertion that the facts collected by Parry at 

 Melville Island, near the magnetic pole, lead to 

 the conclusion that the northern lights do not 

 disturb the needle, but rather have a " calming 

 effect" upon it, is completely contradicted by a 

 more careful perusal of Parry's own journa](^*^), 

 by the beautiful observations of Richardson, 

 Hood, and Franklin in North Canada, and more 

 lately still, by Bravais and Lotten in Lapland. 

 The process in the northern lights is, as we 

 have above observed, the act of restoration of 

 an equilibrium disturbed. The effect upon the 

 needle varies according to the measure of force 

 in the explosion. It was only unobservable at 

 the nocturnal winter station at Bosekop,* when 

 the luminous phenomenon showed itself very 

 feebly and deep on the horizon. The upshoot- 

 ing radiate cyhnders of the northern light have 

 been aptly compared to the flame which, in the 

 closed circuit of the Voltaic pile, arises be- 

 tween two charcoal points at a distance from 

 one another, or, according to Fizeau, between 

 a silver and a charcoal point, and to that which 

 is drawn or thrown off from the magnet. This 

 analogy at all events renders superfluous the 

 assumption of those metallic vapours in the 

 atmosphere which some natural philosophers 



* [Vide Kaemtz's Complete Course of Meteorolo§ry, by 

 C. V. Walker, (Plates, 8vo. Lond. 1845), for a full accouut 

 of the Aurora.— Tb.] 



