and the motion of Auroral Beams. 



From the Record of Auroral Phenomena by Peter Force. 

 Page 37. 1821, April 27. Fort Enterprise, lat. 64|°, long. 113° 



ch moved slowly to the southward. 



A. 1820, Dec. 11. lb. The arches moved slowly to 



Page 102. 1820, Feb. 10. Winter Harbor, lat. 74|°, long. IIC" W. 

 A low arch to the westward, from which pencils appeared to proceed. 

 These pencils had a slow, though very sensible, lateral motion from north 

 to south and vice versa. 



The] 

 of auro 



only three cases of a motion from S. to N. In the aurora of 

 Aug. 28, 1827, at Canandaigua, N. Y., the arch seemed to move 

 back towards the north ; and soon after it moved again to the 

 south more rapidly than ever. In the auroraof Nov. 17, 1835, 

 at New Haven, the auroral zone, after moving for some time 

 toward the south, began to recede northward ; and also in the 

 aurora of Feb. 10, 1820, at Winter Harbor, the auroral pencils 

 had a slow lateral motion from N. to S. and vice versa. 



We may hence conclude that in the United States, great auro- 

 ras almost invariably exhibit a motion from N. to S. with occa- 

 sionally and temporarily a slight retrograde movement from S. 



. The preceding catalogue includes 31 cases in which the mo- 

 tion of auroral beams was described as from E. to W. ; and 15 

 cases of a motion from W. to E. If auroral streamers had a 

 motion exactly from N. to S. then those streamers which were in- 

 cluded between the N. and E. points of the horizon would have 

 an apparent motion towards the E. ; while those streamers which 

 were included between the N. and W. points of the horizon 

 would have an apparent motion towards the west. It seems 

 probable that the apparent motion from E. to W. and from W. 

 to E. is frequently due to an actual motion from N. to S. ; but 

 since the apparent motion towards the W. is twice as frequent 

 as that towards the E. we must conclude that the actual motion 

 of the streamers is from about KKK to S.S. W. 



We thus find a general correspondence between the direction 

 of the electric currents which traverse the earth's surface during 

 displays of the aurora, and the motion of the auroral beams. 

 la the United States, the former move from about K 68° E. to 

 S. m^ ^ ^iiQe tjjg lattgj. move from about K 30° E. to S. 30° W. 



