VAULT OF HEAVEN. 169 



Southern Europe, where I was greatly surprised to hear a vene- 

 rable prelate express an opinion in reference to the fall of aero- 

 lites at Aigle, which at that time formed a subject of considerable 

 interest, that the bodies we called meteoric stones with vitri- 

 fied crusts were not portions of the fallen stone itself, but 

 simply fragments of the crystal vault shattered by it in its 

 fall. Kepler, from his considerations of comets which 

 intersect the orbits of all the planets,* boasted, nearly two 

 hundred and fifty years ago, that he had destroyed the 77 

 concentric spheres of the celebrated Girolamo Fracastoro, as 

 well as all the more ancient retrograde epicycles. The ideas 

 entertained by such great thinkers as Eudoxus, Mensechmus, 

 Aristotle, and Apollonius Pergseus, respecting the possible me- 

 chanism and motion of these solid, mutually intersecting spheres 

 by which the planets were moved ; and the question whether they 

 regarded these systems of rings as mere ideal modes of repre- 

 sentation, or intellectual fancies, by means of which difficult 

 problems of the planetary orbits might be solved or determined 

 approximately ; are subjects of which I have already treated 



ProbL, xiv. 11,) and that the formation of ice itself may be 

 promoted by heat, are deeply-rooted in the physics of the 

 ancients, and based on a fanciful theory of contraries (An- 

 tiperistasis] on obscure conceptions of polarity (of exciting 

 opposite qualities or conditions). (Cosmos, p. 14, and note.) 

 The quantity of hail produced was considered to be propor- 

 tional to the degree of heat of the atmospheric strata. (Aristot. 

 Meteor., i. 12.) In the winter fishery on the shores of the 

 Euxine, warm water was used to increase the ice formed in the 

 neighbourhood of an upright tube. (Alex. Aphrodis., fol. 86, 

 and Pint, de primo frigido, c. 12.) 



* Kepler expressly says in his Stella Martis, fol. 9 : " So- 

 lidos orbes rejeci." " I have rejected the idea of solid orbs;" 

 and in the Stella Nova, 1606, cap. 2. p. 8: " Planets in puro 

 sethere, perinde atque aves in acre cursus suos conficiunt." 

 "The planets perform their course in the pure eth:r as 

 birds pass through the air." Compare, also, p. 122. He in* 



