156 PORT DESIRE. [CHAP, vm 



a large fish moving rapidly through a luminous fluid. To this 

 cause the sailors attributed it ; at the time, however, I entertained 

 some doubts, on account of the frequency and rapidity of the 

 flashes. I have already remarked that the phenomenon is very 

 much more common in warm than in cold countries ; and I have 

 sometimes imagined that a disturbed electrical condition of the 

 atmosphere was most favourable to its production. Certainly I 

 think the sea is most luminous after a few days of more calm 

 weather than ordinary, during which time it has swarmed with 

 various animals. Observing that the water charged with gela- 

 tinous particles is in an impure state, and that the luminous 

 appearance in all common cases is produced by the agitation of the 

 fluid in contact with the atmosphere, I am inclined to consider 

 that the phosphorescence is the result of the decomposition of the 

 organic particles, by which process (one is tempted almost to call 

 it a kind of respiration) the ocean becomes purified. 



December 23rrf. We arrived at Port Desire, situated in lat. 47, 

 on the coast of Patagonia. The creek runs for about twenty miles 

 inland, with an irregular width. The Beagle anchored a few miles 

 within the entrance, in front of the ruins of an old Spanish 

 settlement. 



The same evening I went on shore. The first landing in any new 

 country is very interesting, and especially when, as in this case, 

 the whole aspect bears the stamp of a marked and individual 

 character. At the height of between two and three hundred feet 

 above some masses of porphyry a wide plain extends, which is truly 

 characteristic of Patagonia. The surface is quite level, and is 

 composed of well-rounded shingle mixed with a whitish earth. 

 Here and there scattered tufts of brown wiry grass are supported, 

 and, still more rarely, some low thorny bushes. The weather is 

 dry and pleasant, and the fine blue sky is but seldom obscured. 

 When standing in the middle of one of these desert plains and 

 looking towards the interior, the view is generally bounded by the 

 escarpment of another plain, rather higher, but equally level and 

 desolate ; and in every other direction the horizon is indistinct from 

 the trembling mirage which seems to rise from the heated surface. 



In such a country the fate of the Spanish settlement was soon 

 decided ; the dryness of the climate during the greater part of the 

 year, and the occasional hostile attacks of the wandering Indians, 



