SHOOTING STARS. 209 



ceased."* Thus we see in this simile, after the assumption 

 of a centrifugal revolution which Empedocles perceived in 

 the apparent rotation of the celestial sphere, a centripetal 

 force gradually arise as an ideal antithesis. This force was 

 specially and most distinctly described by the acute inter- 

 preter of Aristotle, Simplicius (p. 491, Bekker). He explains 

 the non-falling of the celestial bodies thus : " that the cen- 

 trifugal force predominates over the proper fall-force, the 

 draiving downward." These are the first conjectures re- 

 specting active central forces ; and the Alexandrian, Johan- 

 nes Philoponus, a disciple of Arnmonius Hermea, probably 

 of the sixth century, as it were, recognizing also the inertia 

 of matter, first ascribes " the motion of the revolutionary 

 planets to a primitive impulse,'" which he ingeniously (De 

 Creatione Mundi, lib. i., cap. xii.) unites with the idea of 

 the " fall, a tendency of all heavy and light bodies toward 

 the Earth." We have thus endeavored to show how a great 

 phenomenon of nature and the earliest purely cosmical ex- 

 planation of a fall of aerolites essentially contributed in 

 Grecian antiquity, step by step, but certainly not by math- 

 ematical reasoning, to develop the germ which, fostered by 

 the intellectual labors of the following centuries, led to Huy- 

 gens's discovery of the laws of circular motion. 



Commencing from the geometrical relations of the periodic 

 (not sporadic^ falling stars, we direct our attention especially 

 to what recent observations as to the divergence or point of 

 departure of the meteors, and their entirely planetary Ve- 

 locity, have made known. Both these circumstances, di- 

 vergence and velocity, characterize them with a high degree 

 of probability as luminous bodies which present themselves 

 independently of the Earth's rotation, and penetrate into our 

 atmosphere from without, from space. The North Amer- 

 ican observations of the November period on the occasion of 

 the falls of stars in 1833, 1834, and 1837, indicated as the 

 point of departure the star y Leonis ; the observations of 

 the August phenomenon, in the year 1839, Algol in Perseus, 

 or a point between Perseus and Taurus. These centers of 

 divergence were about the constellations toward which the 

 Earth moved at the same epoch. f Saigey, who has submit- 



* The remarkable passage alluded to in the text in Plutarch, De Fads 

 in Orbe Luncs, p. 923, is literally translated, " However, the motion of 

 the Moon and the violence of the revolution itself prevents it from fall- 

 ing, just as things placed in a sling are prevented from falling by their 

 motion in a circle." t Cosmos, vol. i., p. 118, 119. 



