THE AUGUST AND NOVEMBER METEORS. 389 



weight, before the cloud begins to be condensed, may be upward of 

 40,000 miles. 



The most striking example of such a cosmical cloud composed of 

 small bodies loosely hung together, and existing with hardly any con- 

 nection one with another, is exhibited in the meteoric showers occur- 

 ring periodically in August and November. It is an ascertained fact 

 that on certain nights in the year the number of meteors is extraordi- 



Fig. 1. 



Balls of i'ire seen through the Telescope. 



narily great, and that at these times they shoot out from certain fixed 

 points in the heavens. The shower of meteors which happens every 

 year on the night of the 10th of August, proceeding from the constel- 

 lation of Perseus, is mentioned in many old writings. The shower of 

 the 12th and 13th of November occurs periodically every 33 years, 

 for three years in succession, with diminishing numbers ; it was this 

 shower that Alexander von Humboldt and Bonpland observed on the 

 12th of November, 1799, as a real rain of fire. It recurred on the 

 12th of November, 1833, in such force that Arago compared it to a fall 

 of snow, and was lately observed again in its customary splendor in 

 North America, on the 14th of November, 1867. Besides these two 

 principal showers, there are almost a hundred others recurring at regu- 

 lar intervals ; each of these is a cosmical cloud composed of small dark 

 bodies very loosely held together, like the particles of a sand-cloud, 

 which circulate round the sun in one common orbit. The orbits of 

 these meteor streams are very diverse ; they do not lie approximately 

 in one plane like those of the planets, but cross the plane of the earth's 

 orbit at widely different angles. The motion of the individual meteors 

 ensues in the same direction in one and the same orbit ; but this direc- 

 tion is in some orbits in conformity with that of the earth and planets, 

 while in others it is in the reverse order. 



The earth in its revolution round the sun occupies every day a dif- 

 ferent place in the universe; if, therefore, a meteoric shower pass 

 through our atmosphere at regular intervals, there must be at the place 

 where the earth is at that time an accumulation of these small cosmical 



