74 COSMOS. 



Phenomena, whose manifestation depends on the accidental 

 concurrence of favouring circumstances, ought not to be dis- 

 believed on account of their rarity. 



The same principle must, I think, be applied to the asser- 

 tion of the profound investigator, Saussure, that stars have 

 been seen with the naked eye in bright day-light, on the 

 declivity of Mont Blanc, and at an elevation of 12757 feet. 

 " Q,uelques-uns des guides m'ont assure avoir vu des etoiles 

 en plein jour; pour moi je n'y songeais pas, en sorte que je 

 n'ai point ete le temoin de ce phenomene; mais T assertion 

 uniforms des guides ne me laisse aucun doute sur la realite. II 

 faut d'ailleurs etre entierement a 1'ombre d'une epaisseur con- 

 siderable, sans quoi 1'air trop fortement eclaire fait evanouir la 

 faible clarte des etoiles." " Several of the guides assured me," 

 says this distinguished Alpine inquirer, " that they had seen 

 stars at broad day -light ; not having myself been a witness of 

 this phenomenon, I did not pay much attention to it, but the 

 unanimous assertions of the guides left me no doubt of its 

 reality. 23 It is essential, however, that the observer should 

 be placed entirely in the shade, and that he should even have 

 a thick and massive shade above his head, since the stronger 

 light of the air would otherwise disperse the faint image of 

 the stars." These conditions are therefore nearly the same as 

 those presented by the cisterns of the ancients, and the chimneys 

 above referred to. I do not find this remarkable statement 

 (made on the morning of the 2nd of August, 1787,) in any 

 other description of the Swiss mountains. Two well-informed, 



tolerably well in the statement that " they have never seen 

 stars by day, but that, when observed at night, through deep 

 shafts, the sky appeared quite near, and the stars larger." 

 I will not enter upon any discussion regarding the connec- 

 tion between these two illusions. 



22 Consult Saussure, Voyage dans les Alpes, (Neuchatel, 

 1779, 4to.) torn. iv. 2007, p. 199. 



