xx i v INTRODUCTION. 



GBOTJP -- The Paumotu Group has two seasons, notwith- 

 standing its very uniform temperature throughout the year, which 

 may be divided into the stormy and fine : the former prevails from 

 November till March, when the sun is vertical, and the temperature 

 has its highest mean; the fine season is from April till October. 

 During the former, violent gales from the west and southwest occur, 

 though the winds blow generally from the northward and eastward, 

 rarely south of the east point, and are accompanied with much rain. 

 These gales, which are frequent, cause a great rise of the waters, which 

 often submerge msiny of the low islands ; on these, numerous evidences 

 are seen of the destructive effects from the abrasion at these times, 

 and I think sufficiently account for the dilapidation which is every- 

 where seen on the west side of the islands throughout the South 

 Pacific. There is no time afforded for the growth of vegetation, be- 

 tween these storms, and often from their violence the debris or soil 

 must be washed entirely away. 



The southeast trades are prevalent in the fine season, with fair 

 weather for most of the time, though they are subject to severe 

 squalls, which last but a few hours. At the time we passed through 

 this group, we found no ocean current to exist. The mean standing 

 of the barometer was 29-964 inches; the mean temperature during 

 August 79 33'; the degree -of moisture '877: the temperature in 

 January, 1841, when visited by the Porpoise, was 81 '4. Although 

 the temperature was so high and without variation, the climate, 

 judging from the healthiness of the natives, and their apparent lon- 

 gevity, is salubrious. The power of the sun's rays, by 94 observa- 

 tions, was 96 sun, 8O8 shade, difference 15'2; greatest difference 

 35, least 1. The thermometers were exposed on a rack con- 

 structed for the purpose, and as free from the influence of reflecting 

 surfaces as possible : the observations were made at corresponding 

 hours each day, and as much as possible under the same circum- 

 stances. 



TAHITI. This island was visited by us in the months of Septem- 

 ber and October, 1839, and February, 1841. The climate of Tahiti is 

 usually spoken of as delightful; but, according to the missionaries and 

 residents, it is found to be very debilitating. The variation of the 

 thermometer is between 60 and 85 Fahr. The mean temperature 

 during our stay, in September and October, was 76'4, in February, 82. 

 In the summer months (from November to March) the Tahitian Group 

 is subject to the winds from the northward and westward, which 



