136 LATITUDE OF ANNAPOLIS. 



rable distances in each direction. The variation was found 

 to be 3° 8' 10" west, while the instrument, was in the build- 

 ing, and 2° 41', when set up at a distance on the college green. 

 The number of observations, has not been sutficient, as yet, 

 to determine the mean amount, accurately. The needle has, 

 of late, exhibited uncommon changes in the variation. The 

 first of these occurred at the time of the aurora, on the 25th 

 of January ; when its oscillations extended through more than 

 a degree, the increase of the variation being to the west. On 

 the evening of the 21 st of April, at eight o'clock, another 

 aurora occurred, in every way resembling the former, except 

 that the waves did not extend so far to the south. It was 

 even more remarkable, however, for one broad column of 

 white light, extending to the zenith, in the direction of the 

 magnetic meridian, traversing the whole arch of crimson light, 

 and retaining its position for fifteen or twenty minutes. It 

 was succeeded by the ordinary pencils, of the same colour, 

 but of momentary duration. The whole sky, to the north, 

 was covered with the same gorgeous veil that was seen here 

 on the 25th of January, extending nearly up to the zenith ; 

 and if the ground had been white with snow, the effect would 

 have been the same. This aurora occurred at about the same 

 age of the moon as the former, a little after opposition, and 

 was not sensibly affected by its presence. The same activity 

 was observed as before in the needle, the variation being 

 increased, for the time, a fall degree to the west. Another 

 remarkable aurora took place here, between seven and eight 

 o'clock, on the 3d of April, when the sky was clouded and the 

 wind blowing hard. The light was seen, notwithstanding, in 

 three separate columns, towards the north and east, reaching, 

 at times to altitudes of thirty degrees, exhibiting occasionally, 

 an orange colour, and fluctuating. On this occasion, the 

 motions of the needle, were watched for a considerable 

 time, and were observed to extend over nearly a degree in 

 short periods, when the instrument was as much as possible 

 secured from the agitation of the building. The tendency, 

 was, as before, to the west. A rise of the mercury in the 

 barometer, of four hundredths of an inch, was, also, observed 

 to take place on that evening, in the course of half an hour. 

 A similar rise, had been observed on the 25th of January. 



