PORTION OF THE COSMOS. AEROLITES. 425 



active central forces ; and in a similar manner, recognising 

 as it were the inertness or force of inertia in matter, Jonn 

 Philoponus, of Alexandria, a scholar of Ammonius Hermese, 

 and probably also of the 6th century, ascribes " the motion 

 of the revolving planets to a primitive impetus," which he 

 combines with the idea of " falling/' i . e. the idea of " a 

 tendency in all matter, heavy or light, towards the Earth" 

 (de Creatione Mundi, lib. i. cap. 12). We have thus 

 attempted to shew how a grand natural pbsenomenon, and 

 the earliest purely cosmical explanation of the fall of aero- 

 lites, contributed materially to promote, in Grecian antiquity, 

 the gradual development, not indeed by mathematical com- 

 bination, of the germs of that which, by the mental labour 

 of succeeding centuries, led to the recognition of the laws 

 of circular motion discovered by Huygens. 



Commencing with the geometric relations of periodical 

 (not sporadical) falling stars, we direct our attention by 

 preference to that which more recent observations have 

 shewn concerning the " radiation," or " points of departure,** 

 of the meteors, and their wholly " planetary velocity." Both 

 these features, of " radiation" and " velocity," characterise 

 them, with a high degree of probability, as luminous bodies 

 independent of the Earth's rotation, arriving in our atmo- 

 sphere from " without," or from the regions of space. The 

 North American observations of the " November period/' 

 on the occasions of the showers of falling stars in that 

 month, in the years 1833, 1834, and 1837, had caused the 

 direction of the star y Leonis to be indicated as the point 

 of departure ; and the observations of the " August phae- 

 nomenon," in 1839, indicated, in the same way, the star 

 Algol in the constellation of Perseus, or a point between 



