Eclipses 



total I saw the last rays of the sun undulating 

 violently and rapidly on the white wall of one of 

 the military buildings of the Saint-Dominic ram- 

 part. The effect was similar to what we observe 

 when the sun's light falls on a wall or a ceiling 

 after having been reflected from the surface of 

 a disturbed sheet of water. The identical 

 phenomenon was repeated at the moment of the 

 sun's emergence ; the undulations, which at first 

 were strong, gradually decreased, and then 

 disappeared at the end of five or six seconds.'' 

 These undulations have been seen since, during 

 every eclipse, by numerous observers; drawings 

 have even been made of them, but their origin 

 remains as mysterious as ever. 



It is evident that at no time could so mar- 

 vellous a phenomenon as a total eclipse remain 

 unnoticed. The ancients had recognised the 

 existence of the corona, and Plutarch tells us 

 that the moon, during an eclipse, " always allows 

 a glow to escape around its rim, which does not 

 permit the darkness to become perfectly black 

 and profound." Even more precise observations 



of the same nature were made during the Middle 



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