RECOMMENDATIONS. 489 



height among the stars ; their motion (whether vertical 

 or horizontal) ; the velocity of motion (by the time of 

 passing from one star to another) ; their changes ; their 

 permanency ; whether they appear to affect the arch, 

 or to be entirely in front of it. 



IV. If there are any black clouds in the luminous region, 

 notice should be taken whether the streamers seem to 

 have any relation to them ; whether the arch seems 

 to have any relation to them ; whether and in what 

 manner they increase or disappear. 



V. If there are waves or flashes of light, the observer 



should notice the time of beginning and of finishing ; 

 the general extent of the flashes (up and down, as 

 well as right and left) ; whether the flash is a real 

 progress of light or successive illumination of different 

 places ; and anything else that strikes him. 



VI. The existence and change of colours will, of course, 

 be noticed. 



VII. From time to time, the needle should be observed. 

 If thei'c are two persons capable of accurate obser- 

 vation, it is most desirable that one should steadily 

 watch the needle, and the other the sky. 



6.) When all is over, the observer should immediately put 

 his rough notes in form, and as soon as possible should com- 

 pare his watch with the regulator or other authority for his 

 time. 



7.) The next day he should, from a celestial globe, take the 

 altitudes and azimuths by means of the stars ; he should reduce 

 his observed time to Greenwich mean solar time, and he should 

 append these reductions to his rough observations. In this 

 state the observations are fit for publication, and adapted for 

 immediate use. It is desirable that they should be transmitted 

 without delay to the Assistant Secretary of the British Asso- 

 ciation, Museum, York. 



FALLING STARS. 



M. Quetelet's mode of observing and recording the charac- 

 teristic circumstances of these meteors is contained in the fol- 

 lowing extract of a letter from him : 



" I take my station out of doors, in a situation which com- 

 mands a good view of the sky, with a good map of the heavens 

 spread out before me. W^hen a falling star appears, I mark on 

 the map the point of its commencement, the line of its course 



