CHAPTER XII 

 STARS IN DAYLIGHT 



WHEN I read lately that from the top of El Misti, in 

 Peru, at an altitude of about 19,000 ft., the sky was 

 found to be somewhat darker, or of a deeper colour, 

 than at sea-level, but that no stars were visible with 

 the naked eye in the day-time, I was reminded of a 

 passage in that very delightful book in which Albert 

 Smith tells the Story of Mont Blanc. It is therein 

 related how that De Saussure was at some pains to 

 experiment upon the intense blue colour of the sky at 

 great altitudes, and how, before he quitted Geneva 

 for his memorable ascent of Mont Blanc, he prepared 

 some sheets of paper of sixteen graduated shades of 

 blue. They were from the deepest colour to the palest 

 tint ; they were, further, numbered from one to 

 sixteen ; and three sets of them were made. One set 

 he left with his friend, M. Senebier, at Geneva ; the 

 second he gave to his son, who remained at Chamouni ; 

 the third he carried to the summit. 



On the day of the ascent he found the sky at Geneva 

 to be of the seventh tint at noon ; at Chamouni it was 

 between the fifth and sixth ; on Mont Blanc between 

 the first and second the deepest bleu du roi. The 

 guides, who were all Chamouniards, and who included 



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