76 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 of 

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

 disc, however inconsiderable it may appear when measured, 

 present any analogy to this phenomenon hi 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 * 



34 Humboldt, in Fr. Von Zach's Monatliche Correspondenz 

 zur Erd-und Himrnels-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'abord 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." 



* 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 star over the field of the great Milan 

 meridian telescope r (See Zach's Correspondence astrono- 



