NATURAL PHILOSOPHY. 175 



ism, he argued that the origin of the aurora was cosmical, the matter of 

 which it was composed being derived from the planetary spaces. He inferred 

 this cosmical origin, from the following reasons : First, from the great 

 extent of the exhibitions, sometimes spreading from east to west, for many 

 thousand miles, and rushing to a height of a hundred miles and more, quite 

 above the region of atmospheric precipitation. Secondly, from the fact that 

 in places differing many degrees of longitude, the different stages of the 

 aurora (beginning, maximum and end) occur at the same hour of the night, 

 indicating that a place on the earth, in. its diurnal revolution, comes succes- 

 sively under the nearest point of the auroral body situated in space. Thirdly, 

 from the velocity of the motions, being too small for light itself, but too great 

 to result from any known terrestrial force, as magnetic or electrical fractions, 

 occasioning a translation of the matter of the aurora. Fourthly, from the 

 periodicity of the aurora, especially its secular periodicity, appearing at long 

 but nearly definite intervals in a grand series of exhibitions, which increase 

 to a maximum and then diminish in number and intensity, until the phe- 

 nomenon, in its grandest forms, vanishes from our nocturnal heavens, a 

 fact which appears to remove it from the pale of terrestrial, and to bring it 

 clearly within the domain of astronomical causes, implying a nebulous body 

 in the planetary spaces, from which the material of the aurora is derived, 

 having a revolution around the sun, and a period in a nearly simple ratio to 

 the earth's periods. 



At the Dublin meeting of the British Association, Capt. Maguire, who 

 commanded the Plover, sent out in search of Sir John Franklin, via of 

 Bhering's Straits, in the course of a discussion, said he wished he could con- 

 vey to the meeting any vivid impressions of the beauty of the aurora as 

 witnessed at Point Barrow, the most northern cape of that part of the Ameri- 

 can continent which lies between Bhering's Straits and Mackenzie's River. 

 It was never seen during the hours of daylight, or those hours which corres- 

 ponded to mid-day, but towards evening its displays began, at first towards 

 the north ; it then extended in splendid arches spanning the entire sky, and 

 seeming to end in beautiful corona? towards the zenith ; these were occasion- 

 ally of the most brilliant and varied tints and colors. It spread gradually 

 more south, and at length died away towards the morning hours in the south. 

 Such were the beauty and interest of these displays, that men and officers 

 constantly, with the thermometer at and below forty degrees below zero, 

 stood out for hours witnessing the glorious scene. During these auroral dis- 

 plays he could not say that he had ever witnessed those violent agitations of 

 the needle that others had described, but the easterly disturbance of the va- 

 riation seemed to be simultaneous with its northerly display, and the westerly 

 to its influence when it had passed to the south. At some distance from the 

 ships, say about five miles, the water shoaled, and the ice had been driven 

 up into beautiful rocky pinnacles ; beyond this, again, the water was always 

 free of ice, and its temperature was frequently found to be twenty-eight de- 

 grees above zero, when that of the air above was even forty degrees below 

 zero ; the consequence was, that it had all the appearance of a boiling sea, 

 so great was the quantity of vapor thrown up from it. 



