But neither the magnetic equator nor the magnetic poles coincide precisely with the geographical equator and poles, and this difference constitutes what is termed the _variation_ of the needle. From calculation, the north magnetic pole had been fixed in latitude 70°, and longitude 98° 30′ west, a spot which Commander Ross approached within the distance of ten miles, in the year 1830, but was unable to verify the site, for want of the requisite instruments. Upon going through a long series of calculations afterward himself, he concluded the above position to have been erroneously assigned, and that the real point lay in latitude 70° 5′ 17″ north, and longitude 96° 46′ 45″ west, a spot on the western coast of Boothia, which he prepared to reach. On the first of June, 1831, at eight o’clock in the morning, he arrived at the site to which his calculations pointed, and found the same day the amount of the dip to be 89° 59′, only one minute less than 90°, the vertical position, which would have precisely indicated the polar station; and the horizontal needles, suspended in the most delicate manner possible, did not betray the slightest movement. The spot was an unattractive level site along the coast, rising into ridges from fifty to sixty feet high, about a mile inland. The wish expressed by the discoverer was natural, that a place so important had possessed more of mark or note, but Nature had erected no monument to denote the spot which she had chosen as the centre of one of her “great and dark powers.” A cairn of some magnitude was constructed by the adventurers, upon which the British flag was planted, and underneath, a canister was buried, containing a record of the interesting enterprise. [Illustration: Aurora Borealis—Loch Leven.] The magnetic needle has frequently exhibited violent disturbance when the Aurora Borealis has appeared. This has led to the surmise that these brilliant lights are connected with the electric and magnetic properties of the earth, though in a manner which we cannot explain. It has been remarked that during the appearance of the aurora the electric fluid may often be readily collected from the air. If a current of electricity also be passed through an exhausted receiver, a very correct imitation of the auroral light will be produced, displaying the same variety of color and intensity, and the same undulating motions. It is highly probable, therefore, that the beautiful and fantastic meteoric display is connected with electricity; but great obscurity rests upon this department of meteorology.