XV RED SNOW 345 



watching a thunderstorm, or hearing in full orchestra a chorus 

 of the Messiah. 



On several patches of the snow I found the Protococcus 

 nivalis, or red snow, so well known from the accounts of Arctic 

 navigators. My attention was called to it by observing the foot- 

 steps of the mules stained a pale red, as if their hoofs had been 

 slightly bloody. I at first thought that it was owing to dust 

 blown from the surrounding mountains of red porphyry ; for 

 from the magnifying power of the crystals of snow, the groups 

 of these microscopical plants appeared like coarse particles. 

 The snow was coloured only where it had thawed very rapidly, 

 or had been accidentally crushed. A little rubbed on paper 

 gave it a faint rose tinge mingled with a little brick -red. I 

 afterwards scraped some off the paper, and found that it 

 consisted of groups of little spheres in colourless cases, each the 

 thousandth part of an inch in diameter. 



The wind on the crest of the Peuquenes, as just remarked, 

 is generally impetuous and very cold ; it is said ^ to blow 

 steadily from the westward or Pacific side. As the observations 

 have been chiefly made in summer, this wind must be an upper 

 and return current. The Peak of Teneriffe, with a less elevation, 

 and situated in lat. 28°, in like manner falls within an upper 

 return stream. At first it appears rather surprising that the 

 trade-wind along the northern parts of Chile and on the coast 

 of Peru should blow in so very southerly a direction as it 

 does ; but when we reflect that the Cordillera, running in a 

 north and south line, intercepts, like a great wall, the entire 

 depth of the lower atmospheric current, we can easily see that 

 the trade-wind must be drawn northward, following the line 

 of mountains, towards the equatorial regions, and thus lose 

 part of that easterly movement which it otherwise would have 

 gained from the earth's rotation. At Mendoza, on the eastern 

 foot of the Andes, the climate is said to be subject to long 

 calms, and to frequent though false appearances of gathering 

 rain-storms : we may imagine that the wind, which coming 

 from the eastward is thus banked up by the line of mountains, 

 would become stagnant and irregular in its movements. 



Having crossed the Peuquenes, we descended into a moun- 



* Dr. Gillies \D./ourn. of Nat. and Geograph. Science, Aug. 1830. This author 

 £iyes the heights of Ihe Passes. 



