THE VOYAGE OF THE BEAGLE 345 



limit of vegetation, and found good quarters for the night 

 under the shelter of some large fragments of rock. We met 

 here some passengers, who made anxious inquiries about the 

 state of the road. Shortly after it was dark the clouds sud- 

 denly cleared away, and the effect was quite magical. The 

 great mountains, bright with the full moon, seemed impend- 

 ing over us on all sides, as over a deep crevice: one morn- 

 ing, very early, I witnessed the same striking effect. As 

 soon as the clouds were dispersed it froze severely; but as 

 there was no wind, we slept very comfortably. 



The increased brilliancy of the moon and stars at this 

 elevation, owing to the perfect transparency of the atmos- 

 phere, was very remarkable. Travelers having observed 

 the difficulty of judging heights and distances amidst lofty 

 mountains, have generally attributed it to the absence of 

 objects of comparison. It appears to me, that it is fully as 

 much owing to the transparency of the air confounding 

 objects at different distances, and likewise partly to the 

 novelty of an unusual degree of fatigue arising from a little 

 exertion, habit being thus opposed to the evidence of the 

 senses. I am sure that this extreme clearness of the air 

 gives a peculiar character to the landscape, all objects 

 appearing to be brought nearly into one plane, as in a draw- 

 ing or panorama. The transparency is, I presume, owing to 

 the equable and high state of atmospheric dryness. This 

 dryness was shown by the manner in which woodwork 

 shrank (as I soon found by the trouble my geological ham- 

 mer gave me) ; by articles of food, such as bread and sugar, 

 becoming extremely hard; and by the preservation of the 

 skin and parts of the flesh of the beasts, which had perished 

 on the road. To the same cause we must attribute the singu- 

 lar facility with which electricity is excited. My flannel 

 waistcoat, when rubbed in the dark, appeared as if it had 

 been washed with phosphorus ; every hair on a dog's back 

 crackled; even the linen sheets, and leathern straps of the 

 saddle, when handled, emitted sparks. 



March 2$rd. The descent on the eastern side of the Cor- 

 dillera is much shorter or steeper than on the Pacific side; 

 in other words, the mountains rise more abruptly from the 

 plains than from the alpine country of Chile. A level and 



