108 SPECIAL RESULTS IN THE URANOLOGICAL PORTION 



to the subject, assume from seven to ten glass heaveis suc- 

 cessively placed over each other like the coats of an onion, this 

 view of the crystal vault passed to the Middle Ages : it has 

 even been preserved to recent times in some of the convents 

 of the south of Europe, where, to my astonishment, a vene- 

 rable dignitary of the Church, in reference to the fall of 

 aerolites at Aigle which excited so much attention, expressed 

 the opinion that what we called meteoric stones, and which 

 were covered with a vitrified crust, were not parts of the 

 fallen stone itself, but pieces of the crystal heaven which it 

 had broken through in falling. Kepler first, two centuries 

 and a half earlier, induced by the consideration of comets 

 cutting through all the planetary orbits, had boasted ( 202 ) 

 of having destroyed the 77 homocentric spheres of the cele- 

 brated Girolamo Fracastoro, as well as all the more ancient 

 retrograding epicycles. How such great minds as Eudoxus, 

 Mensechmus, Aristotle, and Apollonius of Perga, had con- 

 ceived to themselves the possible mechanism and motion of 

 spheres intercalated with each other, and carrying with them 

 the planets, or whether they regarded these spherical 

 systems as ideal contemplations fictions of the intellect by 

 the aid of which the difficult problems of the courses of the 

 planets might be explained and approximately computed, 

 are questions which I have touched on elsewhere, ( 203 ) and 

 which are not without importance in the history of astronomy, 

 when that history attempts to distinguish periods of deve- 

 lopment. 



Before we pass from the very ancient but artificial zodiacal 

 grouping of the fixed stars (as imagined to be set in a 

 solid sphere) to their natural or real grouping, and to such 



