82 METEOROLOGICAL 



three occasions, namely, December the 27th, 

 1827, and December the 1st and 26th, 1828, 

 the aurora, in the form of a rainbow-Hke arch, 

 was seen to cross the magnetic meridian, by the 

 plane of which it was bisected, at right angles. 

 That the true height of the luminous arches of 

 the aurora must be great, is certain from con- 

 temporaneous observations which have been 

 made upon them, by persons situated in distant 

 parallels of latitude. According to Mr. Dal ton, 

 who has recently determined their altitude trigo- 

 nometrically, it is about one hundred miles above 

 the surface of the earth.* The periodical oc- 

 currence of this splendid meteor, and the motion 

 from north to south, which the luminous arches 

 are usually perceived to have, well deserve the 

 attention of the scientific meteorologist. 



With regard to the meteors known by the 

 appellation of shooting stars, I have little to 

 observe, except that their motions do not appear 

 to be influenced either by currents of air, or by 

 the earth's magnetism ; and that their elevation 

 is probably considerable. The great velocity 

 with which they pass through that portion of their 

 path in which they are visible, and the various 

 and opposite directions they pursue on the same 



♦ Transactions of the Royal Society for 1828, Part IL 



