[ v INTRODUCTORY LETTER. 



the direction of the Aurora, the time of observation, and the locality, by parallel 

 and meridian, are stated in every instance where it was found possible to do so. 



I may venture to add that the observations here given, go far, as it appears to 

 me, to establish the following points in regard to the Aurora Borealis : — 



1. That in the higher northern latitudes it frequently first appears to the east- 

 ward, or to the westward, or to the southward of the observer, and hence is not 

 strictly a north polar light. 



2. That it is often at a low elevation, and sometimes near the surface of the 

 earth, within the range of the vision of the observer. 



3. That north of the 70th degree of north latitude it is less frequent and less 

 brilliant than to the southward of that parallel. 



4. That on and in the vicinity of the Atlantic Ocean and other open waters, it 

 is most frequent and most brilliant. 



5. That the season for its appearance is mostly between the autumnal and the 

 vernal equinox. 



C. That the time of its appearance is in most cases from six o'clock P. M. to 

 midnight. 



PETER FORCE. 



Washington, May 1, 1856. 



