METEORS AND AEROLITES. 293 



obscure to the untutored reader much of what even the 

 ablest men have written on the subject. In the work of MM. 

 Gravier and Saigey for instance, the history of Meteorites, 

 though divided into periods, is perplexed by the continual 

 passage from one class to another, and from observation to 

 theory. We have ourselves endeavoured to avoid this per- 

 plexity, as far as it seemed to be possible under our actual 

 io-norance of many of the relations of the phenomena. In 

 proceeding now to speak of the meteoric globes or fire- 

 balls and the shooting-stars, we are following a provisional 

 arrangement which may hereafter be cancelled; and are 

 adopting names as we find them, since no better nomencla- 

 ture has yet been brought to this part of science. The same 

 thing has happened in other sciences ; and such steps are 

 natural in the history of all human progress. 



The luminous globes are those in closest connection with 

 the aerolites ; inasmuch as we have various well-attested in- 

 stances of stones single or numerous falling at the time 

 of such appearances, and in sequel to explosions which would 

 seem to rend asunder some larger volumes of matter. The 

 following description of the ordinary character of the Bolide 

 we take chiefly from our French authors, who correct some 

 exaggerations of Chladni on this subject. They have claim 

 to be considered an authority, since one of them, by incessant 

 observation for several years, witnessed as many of these 

 great meteors as the actual number noted during the same 

 period by all other observers on the globe. 



These meteors appear to move in the arcs of great circles. 

 They do not come equally from all points of the horizon, but 

 affect certain principal directions. No movement of rotation 

 is recognised in them. Their apparent disk is greatly en- 

 larged by irradiation ; and is occasionally seen to exceed the 

 circumference of the full moon which, at the distance of 

 110 miles, would give a diameter of about a mile. Their 



