GENERAL DIRECTIONS. 49 



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 diffuse 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 

 evening, from 8 to 10 o'clock, or later. Record the result, 

 whether there be an aurora or not. 



2. Note the time of observation, and compare the watch used 

 with a good clock, as soon after as is convenient. 



3. Make a return of the latitude and longitude of the station. 



4. Note the class to which the auroral phenomenon belongs. 



5. If it be an arch, note the time when the convex side reaches 

 any remarkable stars, when it passes the zenith, disappears, &c. 



6. If the arch be stationary for a time, mark its position 

 among the stars on the accompanying map, so that its altitude 

 may be determined. 



7. If it be a streamer or beam, mark its position on the map, 

 and the time of its beginning and ending. 



8. If motion be observed in the beams, note the direction, 

 whether vertically or horizontally, to the east or west. 



9. Note the time of the formation of a corona, and its posi- 

 tion among the stars. 



10. Note the time of the appearance of any black clouds in 

 the north near the aurora; also, if the sky be suddenly overcast 

 with a mist at any time during the auroral display. 



11. Give the direction and force of the wind at the time. 



12. Note if any electrical effects are observed. 



13. Note the effect upon a delicately suspended magnetic 

 needle. 



