78 COSMOS. 



seven to eight minutes, and ceased long before the sun's disc 

 appeared above the horizon of the sea. The same motion was 

 discernible through a telescope, and there was no doubt that 

 it was the stars themselves which moved. ** Did this change 

 of position depend on the much contested phenomenon ol 

 lateral radiation ? Does the undulation of the rising sun's 

 disc, however inconsiderable it may appear when measured, 

 present any analogy to this phenomenon in the lateral alteration 

 of the sun's margin ? Independently of such a consideration, 

 this motion seems greater near the horizon. This phenomenon 

 of the undulation of the stars was observed almost half a cen- 

 tury later at the same spot by a well-informed and observing 

 traveller, Prince Adalbert, of Prussia, who saw it both with 

 the naked eye and through a telescope. I found the obser- 

 vation recorded in the Prince's manuscript journal, where he 

 had noted it down, before he learned, on his return from the 

 Amazon, that I had witnessed a precisely similar phenomenon. 2 * 



24 Humboldt, in Fr. Von Zach's Monatliche Correspondent 

 zur Erd-und Himmels-Kunde, bd. i. 1800, s. 396 ; also Voy, aux 

 Reg. equin., torn. i. p. 125. " On croyait voir de petites fusees 

 lancees dans 1'air. Des points lumineux eleves de 7 a 8 degres, 

 paraissent d'a^ord se mouvoir dans le sens vertical, mais puis 

 se convertir en une veritable oscillation horizontale. Ces 

 images lumineux etaient des images de plusieurs etoiles agran- 

 dies (en apparence) par des vapeurs et revenant au meme 

 point d'ou elles etaient partis." " It seemed as if a number of 

 small rockets were being projected in the air ; luminous points, 

 at an elevation of 7 or 8, appeared moving, first in a vertical, 

 and then oscillating in a horizontal direction. These were the 

 images of many stars, apparently magnified by vapours, and 

 returning to the same point from which they had emanated." 



96 Prince Adalbert of Prussia, Aus meinem Tagebuche, 

 1847, s. 213. Is the phenomenon I have described connected 

 with the oscillations of 10" 12", observed by Carlini, in the 

 passage of the Polar &tar over the field of the great Milan 

 meridiai telescope? (See Zach's Correspondence astrono- 



