England to Fort Vancouver, 29^ 



We crossed the part of the Atlantic where Maltbrun, in 

 his Geog. Univ. (Transl. i. 322), places the Mer de Sargasso, 

 but not a vestige of it was seen. The 1st February 1833, was 

 remarkable for the sudden and great oscillations of our barome- 

 ter, which cannot be accounted for in the state of the winds and 

 weather; our position at the time was in Lat. 39° S. Long. SG"* 

 W. ; it would be highly interesting to connect this with any 

 striking phenomenon in other parts of the globe, particularly in 

 the adjoining continent of South America. On the 19Ui October 

 1832, I collected in the basin above referred to 3630 gr. of 

 rain water, between noon and 6 p. m. This, of course, is not 

 the true quantity of rain which fell, as some would necessarily 

 he returned into the air by evaporation, from the exposure of so 

 large a surface in the basin to the air. 



It would be but an inadequate outline that I could give 

 you of the impression that the magnificent constellations of 

 the southern hemisphere produced upon me, after the elo- 

 quent delineation given by Humboldt in his Personal Narra^- 

 tive, which, I dare say, is fresh in your recollection, and 

 which, I assure you, is not exaggerated. Neither will I occupy 

 your time by dwelling upon the splendours of a tropical sun- 

 set, which has so often been the theme of voyagers, except 

 to mention a circumstance which I do not remember to have 

 been particularly attended to, but which, 1 think, may be con- 

 sidered as one of the strongest proofs of the remarkable trans- 

 parency of the atmosphere in these latitudes ; it is the violet hue 

 assumed so regularly by the ether in the western horizon, a short 

 interval after sunset. I have never observed a tint of the sky 

 exactly similar in our European skies, and perhaps it tnay be 

 explained in the following way : the rays of white light are de- 

 composed into the prismatic colours, in consequence of the 

 greater density of the air at sunset, both from accumulated vai 

 pours, and a greater length of atmospheric column that they 

 have to traverse ; and those least refrangible, such as red and 

 orange, are what usually in northern climates alone reach the 

 e^e, while, in tropical climates, where the air is more sdrene, we 

 may suppose that those more refrangible will reach the eye also; 

 as the yellow, green, blue, indigo, violet, which agrees with the 

 phenomena observed. We had a fine opportunity of observ- 



