in the Rarified Air of High Mountains. 77 



distance when the density was not more than 0*72, that at 

 the level of the sea, as at Faulhorn ; and even when the 

 density was only 0'64 as on Mont Blanc, we have found a 

 greater distance than on the plain. 



I place the silence in the first rank among these causes. 

 The summit of the Faulhorn is 900 metres above the limit 

 of trees and of the most elevated chalets : the rustling of the 

 branches agitated by the wind, the song of birds, the hum- 

 ming of insects, the murmuring of the brooks, and the dash 

 of the cascades do not reach this height ; hence there is a 

 repose which is only disturbed by the noise of the wind or of 

 the thunder. All travellers are thus struck with the silence 

 which reigns, especially during the night. This silence is 

 still more profound in calm weather on the grand plateau of 

 Mont Blanc. On the Faulhorn, we still hear the grass sigh 

 under the breath of the wind ; the noise of numerous water- 

 falls which tumble from the flanks of the mountain may still 

 be carried up, though feebly, by the ascending currents of 

 air ; noisy birds approach the summit ; and in the heat of 

 summer the cows and goats venture even to these heights. 

 There is nothing similar on the grand plateau of Mont Blanc ; 

 a plain of snow surrounded by rocks elevated 3910 metres 

 above the sea, 1850 metres above the limit of trees, and 1450 

 metres above the highest torrents produced by the melting 

 glacier. The silence of death which reigns in calm weather 

 over these fields of ice produces one of the most solemn im- 

 pressions which I have experienced. This silence is so pro- 

 found that sounds are heard at a great distance, although 

 their intensity be much less than in the low country .^ The 

 fall of avalanches so common in these high regions is accom- 

 panied with a noise which has no relation to the masses of 

 the snow and ice precipitated from the neighbouring rocks : 

 nevertheless it is always heard, because the least sound is 

 perceived by the ear. Similarly, on the top of the Faul- 

 horn, we hear very distinctly the avalanches which fall from 

 the sides of the Wetterhorn ; the horizontal distance of the 

 two summits is 9700 metres, and the sound moves in a stra- 

 tum of air comprised between the altitudes of 2600 and 2700 

 metres. 



