1821.] Ascent to the Summit of Mont Blanc, 381 



greatest degree of heat we experienced, or rather seemed to 

 experience, for it was not indicated by the thermometer, wa^ 

 about two, p.m. The glare of the sun, from which we had no 

 direct shelter, and the reaction of his rays becoming more pain- 

 ful from prolonged exposure to them, must have caused this 

 sensation. The wind afterwards increased, and when I quitted 

 the summit, the thermometer in the sun and full air was 19°. 

 This is a much greater degree of cold, and a more extended 

 variation of temperature, than was felt by Saussure, though his 

 ascent was in the same month of the year, and only a few days 

 earlier — a proof of the changes prevalent at such elevations. 

 That eminent philosopher mentions that by placing himself in the 

 shade, he was able to see the stars ; but though I lay down in 

 the snow, and had my guides with their cloaks. Sic. spread 

 about, so as to form a kind of night around me,. I was not 

 equally fortunate, which may, perhaps, be attributable to the 

 difference of wind and atmosphere. Sound is imperfectly con- 

 veyed at great heights, and it is not in the slighest degree rever- 

 berated upon Mont Blanc. I caused a pistol to be discharged 

 several times at various distances ; but the cessation of the 

 report was instantaneous, and when I had it fired into a cavity,, 

 in the snow, and lay down 30 or 40 paces off, the effect wasv 

 the same. 



While upon the summit, I sent my guides to break off some of 

 the highest visible rock * in Europe, which is considerably 

 lower towards the SE ; and I send you specimens, with some 

 stone vitrified by lightning, which is occasionally found in that 

 direction. This is the only effect of that element discernible 

 upon Mont Blanc, which, by its form, and the snowy cope with 

 which it is eternally crowned, is shielded from its influence. At 

 three o'clock, having assembled my guides, and caused them to 

 join with me in drinking to the prosperity of Old England, we 

 commenced our descent ; and in an hour and a half reached the 

 Grand Plateau. We were linked in ascending, and passed the 

 declivities, which were not too precipitous, by gliding down 

 them upon our haunches — a method attended with no other 

 inconvenience, except that the foremost in the train were 

 covered with the rubbish raised by the passage of those behind. 

 In this manner we proceeded, and arrived at the Grand Mulct 

 in three howrs and twenty minutes. We found that two ava- 

 lanches had fallen in different parts of our path, neither of them, 

 indeed very large, but quite sufficient to have overwhelmed the^ 

 whole party. 



* Dr. Du Hamel is mistaken in supposing that he had procured pieces of the '' high- 

 est visible rock in Europe," that being situated only about 250 feet below the top of the 

 mountain, but several Uiousand above the spot, whence he seems to have got his speci- 

 mens. This rock is the protogene of Prof. Jurine, but the Rocher Rouge is granite, 

 and has a reddish hue, whence its name. 



