272 M. Quetelet on Shooting Stars. 



angle of less than 45° with the vertical ; 14 were between 45° and 

 the horizon; 8 between the horizon and 135°; and only 1 was 

 still more elevated. With regard to the azimuths, of 34 trajecto- 

 ries, 23 had a direction southwards and 11 to the north, 21 to 

 the west, and 1 3 to the east. Separating the shooting stars into two 

 groups, we find 25 of them whose course inclines more to a south- 

 west direction, or whose azimuth is less than 135° to the west and 

 45° to the east, and only 9 are in the other half portion of the hea- 

 vens. This difference seems to be connected with the direction of 

 the motion of the earth in its orbit, admitting that the meteors in 

 question may be considered as small asteroids. 



3. The brilliancy of shooting stars is very various; these meteors 

 sometimes surpass Jupiter and Venus in light, and sometimes they 

 are only perceived by the help of finders. Some leave after them 

 luminous tracks visible for some seconds after their passage, which 

 are not to be confounded with those luminous and rapid traces 

 which depend upon the length of the sensation on the retina. The 

 trajectories appear generally as straight lines. Some of them, how- 

 ever, are very sensibly curved ; they are far from exhibiting a con- 

 tinued brilliancy in their whole extent. 



4. The velocity of shooting stars has not been capable of deter- 

 mination with any precision, except for a very small number of these 

 meteors*: it is from 3 to 10 leagues a second. 



5. As to the mean number of shooting stars which can be ob- 

 served at any given epoch of the year, after having particularly ex- 

 amined this question,f {Bulletin del' Acad. Royale de BruxelleSyVol.ui. 

 p. 404, et seq.) I have come to this result, that a single observer or 

 several observers directed towards one and the same region of the 

 heavens can see, on an average, eight shooting stars an hour, and 

 that several observers, placed so as to see the different regions of 

 the heavens, may reckon twice that number of them. 



6. It would seem that a cause exists which produces, from about 

 the 8th to the 15th of November, more frequent appearances of shoot- 

 ing stars. I have also thought that I remarked a greater frequency 

 of these meteors in the month of August (from the 8th to the 15th). 



7. As to the nature of shooting stars many doubts still remain on 

 this subject : are they to be considered as asteroids, according to 

 an hypothesis of some standing ; or as stones shot from the volcanos 

 of the moon, according to the opinion of Benzenberg, Chladni, and 

 other physicists J? I should be inclined to think that a distinction must 

 be made between the shooting stars which leave luminous trains 

 after them, persistent and often characterized by sparks, and those 

 whose course is marked by a trace of light as momentary as the ap- 

 pearance of the star, and which is only owing to the duration of the 

 impressions on the retina. The first appear to me to be really 



* For six of these meteors whose velocity I was able to calculate, J 

 found 5 leagues, 7*6, 4*5, 3*0, and 3*4, mean 4*7 leagues. 



t See the preceding paper. Edit. 



% Die Sternschuppen sind Steine aus den Mondvul/canen, Benzenberg, 

 Bonn, 1834. 



