Sect. X.] 



AND BAROMETBIC CURVES. 



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Ixiimediately connected witli this part of the outward- 

 bound voyage, hourly observations, as often as circum 

 stances will permit, while the ships are saihng from the 

 Madeiras to the equator, will be extremely valuable in 



elucidating the origin of the great system of south- 





westerly atmospheric wave^ that traverse Europe, and in 

 furnishing data for comparison with the amount of oscilla- 

 tion and other barometric phsenomena in the Gulf of 

 Mexico and the Caribbean Sea, a portion of the torrid 

 zone essentially different in its configuration and in the 

 relations of its area to land and. water, as contra- 



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distinguished to the northern portion of the African 

 continent ; and these hourly observations are the more 

 desirable as the vessels may approach the land. They 

 mny be discontinued on passing the equator, and the 

 three-hourly series resumed. 



Tlicre are two points in the southern hemisnhere 



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between 80^ west longitude, and 30° east longitude, that 

 claim particular attention in a barometric point of view% 

 viz,. Cape Horn and the Cape of Good Hope ; the laiM^. 

 is within the area marked out for the three-hourly obser- 

 vations, and too much attention cannot be paid to the 

 indications of the barometer as vessels are approaching or 

 leaving the Cape. The northern part of the South 

 Atlantic Ocean has been termed the true Pacijic Ocean of 



the ivorld ; and at St, Helena a gale was scarcely ever 

 known ; it is also said to be entirely free from actual 

 storms (Col. Reid's 'Law of Storms,' 1st edition, p. 415). 

 It may therefore Le expected that the barometer 

 present in this locality but a small oscillation, and ships 

 in sailing from St. Helena to the Cape will do well to 



y. 



