xv iii INTRODUCTION. 



terous character are due to the influence of the neighbouring continent, 

 it is impossible to conjecture, but it appears very reasonable to suppose 

 that the peculiar formation of this part of South America, already 

 referred to, may exercise sufficient influence over the aerial currents 

 to cause the effects we experience in these latitudes. If condensa- 

 tion and rarefaction are continually going on over a large surface, we 

 see sufficient cause why these currents should not only prevail in the 

 directions indicated, but that they should continue to keep up the 

 same efforts to restore the equilibrium which is being constantly 

 destroyed, and the more rapid the action is on the one hand the more 

 violent it would be on the other. That these winds are the most 

 boisterous during the summer of the southern hemisphere, we believe 

 is generally admitted : such has been the result of our inquiries. 



On arriving at the forty-second parallel, we were met by the 

 northerly monsoons of the coast of Chili, which continued without 

 cessation until we reached the latitude of 36 south, when we encoun- 

 tered a gale, during the continuance of which the barometric column 

 had a downward tendency, and did not begin to rise until the height 

 of the gale was over. Afterwards, we were favoured with the 

 southeast trades. This length (nine days' duration) of the northerly 

 monsoons at this early day (12th May) was unlocked for, but from 

 information I received, such storms frequently occur from April to 

 September. 



After our arrival at Valparaiso, I found that light north winds had 

 prevailed there, with calms and fog, which latter is a common accom- 

 paniment. It has been remarked above that a large amount of rain 

 falls on the west coast of South America to the southward of the for- 

 tieth parallel, notwithstanding the atmosphere is not near the actual 

 point of saturation : the fact that the crops are gathered in a wet state, 

 and spread over the floors of the houses to be dried and cured, is con- 

 clusive that such is the case, and that the process of evaporation must 

 be extremely rapid. Captain King, during his stay at San Carlos in 

 1829, gives the standing of the barometer reduced to 32 : for Septem- 

 ber 30-061, October 29-979, November 29-898 ; the mean temperature 

 50-5; the quantity of rain 10 - 79 in., and the degree of moisture -833, 

 and this was considered the fine season. 



VALPAEAISO Our arrival at Valparaiso was in May, the last 



autumnal month of the southern hemisphere. Our stay was limited 

 to a few weeks. Through the kindness of Mr. Robert Heath, of Val- 

 paraiso, we were allowed to take a copy of his meteorological observa- 



