INTRODUCTION. xxix 



low as 24 inches; the thermometer at 6 A. M. of the 17th stood at 

 88, being nearly 8 above the mean standing of the instrument at 

 that season of the year. 



In 1849, December 26th, they experienced a severe storm, which 

 continued for two successive days : this storm was not so violent in 

 regard to the force of the wind, but the sea was very destructive, 

 rising high, and it is remarked that islets were raised on the reef on 

 the north side of Upolu several feet above high water mark : the 

 wind blew from the east, and came round to the north and northwest. 

 This gale appears to have been of great extent, for it was felt at 

 both the Society and Hervey Groups. 



SAMOA GROUP TO SYDNEY, NEW SOUTH WALES We had very fine 



weather on this passage, until we passed outside of the southeast 

 trades, in latitude 22 south, when the wind changed to the northward 

 and westward, then to southwest, and finally to the northeast and 

 north, as we approached the coast of New South Wales. 



After we reached the longitude of 175 east, and the latitude of 

 17 south, the temperature of air and water fell rapidly, equalling one 

 degree of temperature for each degree of latitude, till we reached the 

 parallel of 33 south, and 160 east longitude. The barometer in this 

 passage rose '159 ; temperature of the air fell 12-33, and the water 

 13-75; mean degree of moisture '833. 



Sydney lies upon the same parallel of latitude with Valparaiso, yet 

 differs 10 in the mean annual temperature. The cause is obvious. 

 The ocean which bounds both coasts has also this same difference : 

 one is washed by a tropical current, while that of the other has a 

 polar stream flowing along its shores. 



On other coasts where the same causes exist, like results are found : 

 the eastern coast of South America differs from the western to nearly 

 the same amount, and the same might be shown of others, did the 

 space allotted for these remarks permit. In comparing temperatures 

 on the same parallel in the northern and southern hemisphere, some 

 interesting results are obtained. The island of Raratonga, one of the 

 Hervey Group, latitude 21 14' south, longitude 160 west, has a mean 

 annual temperature of 75-61. The lowest temperature was 60, in 

 July and August, the highest 89, in December, January, and Feb- 

 ruary, differing 29. Oahu, one of the Hawaiian Group, lies in lati- 

 tude 21 18' north, longitude 158 west ; the mean annual temperature 

 75 - 8 : the highest degree of heat in June, for 12 years, has been 90 ; 

 lowest 53 in January; difference 37. These are both high islands, 



8 



