METEOilOLOGY. 



INSTRUCTIONS TOR OBSERVATIONS OF THE AURORA.* 



GENERAL REMARKS. 



Thoiigli the aurora borealis lias received attention during a consid- 

 erable portion of the last two centuries, definite information is still 

 wanting on several points -which may serve as the basis of a sound 

 induction as to its cause. These relate particularly to the actual fre- 

 quency of the appearance of the meteor ; its comparative frequency 

 in the different months of the year and different hours of the day ; 

 the connexion of the appearance of the meteor with other atmospher- 

 ical phenomena ; the elevation and extent of visibility of the arch ; 

 and whether the same or different phases are presented to individuals 

 at different stations at the same moment of time ; finally, the precise 

 influence of the arches, streams, &c., on the magnetic condition of 

 the earth ; and whether any unusual electrical effects can be observed 

 during the appearance of the meteor. 



Auroral phenomena may be divided into the following classes : 



1. A faint light in the north, without definite form or boundary. 



2. A diffused light, defined by an arch below. 



3. Floating patches of luminous haze — sometimes striated. 



4. One or more arches, resembling the rainbow, of uniform white 

 color, retaining the same apparent position for a considerable time, 

 and varying in luminosity. 



5. A dark segment, appearing under the arch. 



6. Beams, rays, streamers, waves, transverse and serpentine bands, 

 interrupted or checkered arches, frequently tinged with color, and 

 showing rapid changes in form, place, and color. 



7. Auroral corona, or a union of beams south of the zenith. 



8. Dark clouds accompanying the diftuse light. 



9. Sudden appearance of haze over the whole face of the sky. 



The following may serve as a scale of brightness : 



1. Faint. 2. Moderate. 3. Bright. 4. Very bright. 



GENERAL DIRECTIONS. 



1. Make a regular practice of looking for auroras every clear eve- 

 ning, from 8 to 10 o'clock, or later. Record the result, wliether there 

 be an aurora or not. 



«s These instructions are principally adopted from those used in the Observatory at 

 Toronto, Canada. 



