INTRODUCTION. xv 



opposite effects is believed to be one and the same. The westerly 

 winds which prevail on the Pacific coast, after being deprived of 

 their moisture by condensation on the Andes, rush onward towards 

 the pampas to supply the partial vacuum produced by the heated 

 surface of the plains ; being destitute of moisture they absorb it from 

 the soil, rendering it dry and unproductive, and causing the exces- 

 sive evaporation that is experienced in the salt lakes of the interior, 

 which are said to form a crust of salt of considerable thickness on 

 their surface in twenty-four hours. 



BIO NEGRO TO ORANGE HARBOUR. The passage from Rio Negro to 

 Orange Harbour was made in the month of February. In the lati- 

 tude of 44 south the temperature of both air and water fell 11, 

 which was in part owing to our having entered the cold currents 

 from the south : the waters along the coast are of a higher tempe- 

 rature, which may be owing to the prevalence of northerly currents, 

 or the influence of the tides. A farther depression of the barometer 

 took place, with an increase of the degree of moisture. The winds 

 and changes of the weather had become sudden, and everything 

 betokened, as we approached Cape Horn, that we had entered an 

 inclement and fickle climate. Refractions, and the phenomena of 

 halos, parhelias, &c., were frequently seen ; some of these have been 

 previously described in the Narrative of the voyage, Vol. I., page 112, 

 (4 to. edition.) The weather in the immediate neighbourhood of 

 Cape Horn we found delightful, with light easterly winds, which, 

 except at the periods of the equinoxes, are uncommon. The winds 

 from the time of our leaving the Rio Negro were from the southwest, 

 and at times blew in violent gales of short duration, accompanied 

 with sleet and snow, although it was midsummer. 



ORANGE HARBOUR. Orange Harbour is situated within the collection 

 of islands which form the southern point of the continent, and thirty 

 miles to the northward of Cape Horn, on the west side of the Bay 

 of Nassau, which is surrounded by undulating hills, six hundred to 

 one thousand feet in height, covered with a dark forest of birch, 

 beech, willow, &c. The mountains to the north are seen capped with 

 snow. Many of the high peaks are entirely destitute of vegetation, 

 exhibiting only a bold projecting outline of bare rocks. The soil is 

 found to be saturated with water, and covered with a growth of 

 mosses, even on the highest hills. The face of the country indi- 

 cates pretty accurately the nature of the climate. Our stay was 

 from the beginning of February till the latter part of April. 



