METEORS. 181 



meteor had so much hydrogen in its iron, that the inference 

 was, " the meteorite was extruded from a dense atmosphere of 

 hylrofjen gas." 



Tin- third is, a discovery which has lately been announced 

 i'.iapart-lli, that the great star showers of November, which 

 occur crery thirty-three years, have been hitherto preceded by a 

 fonift. There is no doubt, then, but that it is the great pres- 

 sure of a comet's atmosphere on the atmosphere of the earth 

 which causes the atoms to combine and to form meteors. We 

 have also no doubt, that the yearly display in August, and 

 November, will be found traceable ere long to a similar cause ; 

 or to some combination of the atmospheres by which there 

 is more pressure exerted at one time than at another. The 

 meteors which we see on ordinary occasions, are probably only 

 caused by the constant daily effect of pressure on the atmos- 

 phere. 



