472 THE POPULAR SCIENCE MONTHLY 



teen centuries was universally regarded as a kind of astronomical bible. 



One of the curious astronomical superstitions that originated with 

 the Chaldeans, and which persisted almost to our own times, was that of 

 the crystalline spheres. The idea of a spherical universe was a very 

 natural one. It was difficult to see how thousands of bodies could re- 

 volve around the earth for generations, without change in their rela- 

 tive positions, unless there was something to retain them in their 

 places. It was believed that the planets and stars were set in a series 

 of concentric orbs or spheres, each so perfectly transparent that bodies 

 in the outer ones were visible through all the intervening ones. The 

 drawing shows the order of the spheres and the system of the universe 

 according to Ptolemy. The earth is in the center enclosed by the 

 sphere of the moon, beyond are the concentric spheres of Mercury, 

 Venus, the sun, Mars, Jupiter and Saturn. Outside of all are the crys- 

 talline heavens and the abode of the blessed. 



The revolution of the spheres was supposed to produce the most 

 exquisite music which filled all celestial space, but such was its refined 

 quality that it was inaudible to mortal ears. One of the most sublime 

 passages of Shakespeare describes this music: 



Sit, Jessica. Look how the floor of heaven 



Is thick inlaid with patines of bright gold. 



There is not the smallest orb which thou beholdest 



But in his motion like an angel sings, 



Still quiring to the young-eyed cherubims: 



Such harmony is in immortal souls; 



But while this muddy vesture of decay 



Doth grossly close it in, we can not hear it. 



The following parallel lines are from Milton's " Arcades " : 



In deep of night when drowsiness 

 Hath lock'd up mortal sense, then listen I 

 To the celestial Sirens harmony, 

 That sits upon the nine infolded spheres. 

 Such sweet compulsion doth in music lie, 

 To lull the daughter of Necessity 

 And keep unsteady Nature to her law, 

 And the low world in measured motion draw 

 After the heavenly tune which none can hear 

 Of human mould, with gross unpurged ear. 



Astronomy has always been the favorite science of the poets. The 



frame-work of Dante's " Paradise " is constructed on the Ptolemaic 



system. His ten heavens are arranged in the exact order of those 



shown in the drawing. The crystal orbs are rotated by angels. He 



says: 



The virtue and motion of the sacred orbs, 

 As mallet by the workman's hand must needs 

 By blessed movers be inspired. 



It may be said that during the Christian era, up to the thirteenth 



