720 THE UNIVERSE. 



them; whoever speaks of them is bound to show them. 

 Then show them!" But this is what no one has yet 

 done. 



I have vainly sought for these atmospheric germs, in- 

 vented to supi^ort certain hypotheses, and have never been 

 able to find them. Two observers, equally illustrious for 

 their learning and the splendour of their diction, P. Mante- 

 gazza of the university of Pavia, and N. Joly of the faculty 

 of Toulouse, have not been more fortunate than myself. 



But although the atmosphere is not surcharged or 

 saturated with these indiscoverable eggs, it must yet be 

 admitted that notwithstanding its transj^arence and pene- 

 trability, there are an immense number of invisible cor- 

 puscules floating in it. Is there any one who has not re- 

 cognized this in entering a dark place traversed by a ray 

 of light? The beholder is quite surj^rised to see the infi- 

 nite variety of all the objects whirling about in it, rising 

 and falling, so as to form iridescent and sparkling waves. 



These light corpuscules represent the remains, the 

 detritus of all bodies on the surface of the earth, which 

 have been borne away by the agitation of the atmosphere. 



In the open sea and in calm weather, scarcely any 

 motes are seen in a ray of light; a few specks of dust de- 

 tached from the ship alone float in it. 



On the summit of a lofty mountain Ave notice the same 

 paucity of corpuscules. Xear the crater of Etna the breeze 

 only lirought to us particles of ashes and sulphur thrown 

 out by the volcano. 



But so soon as we abandon the solitudes of the sea or 

 the mountains, the nearer we approach populous cities, the 

 luore does the air become loaded with invisible particles. 

 The catalogue of these is in reality only the summary of 

 all that man makes use of for his wants or pleasures. 



