SHOOTING STARS. . 213 



"The mean number o{ spoi'adic shooting stars appearing 

 there has been found, from many years of observation (be- 

 tween 3 and 8 years), a fall of from four to five in the hour. 

 This is the ordinary condition when nothing periodic occurs. 

 The mean numbers of sporadic meteors in the individual 



months give for the hour, January'-, 3-4 ; February, ; 



March, 4-9 ; April, 2-4 ; May, 3-9 ; June, 5-3 ; July, 4-5 ; 

 August, 6-3 ; September, 4*7 ; October, 4'5 ; November, 5-3 ; 

 December, 4"0. 



" Of the periodic meteors there may be expected, on thf 

 average, in each hour, above 13 or 15. For a single period, 

 that of August, the stream of Laurentius presented the follow- 

 ing gradual increases from sporadic to periodic, upon an av- 

 ej .ge of from three to eight years of observation • ' 



The last year gave for the hour, notwithstanding the cleai 

 moonlight : 



On the 7th of August 3 Meteors. 



8th 



9th 

 10th 

 11th 

 12th . 



(According to Heis, there were observed on the 10th of Au 

 gust : 



1839, in one hour, 160 Meteors. 



1841 " 43 



1841 " 50 



In the August meteor-stream in 1842, there fell at the time 

 of the maximum, in ten minutes, 34 shooting stars.) All 

 these numbers refer to the circle of vision of one observer. 

 Since the year 1838, the November falls have been less brill- 

 iant. (On the 12th of November, 1839, Heis still counted 

 hourlv 22 to 35 meteors ; likewise, on the 13lh of Novem- 



