XXX 



INTRODUCTION. 



situated in mid ocean, and within the range of the trade winds of 

 both hemispheres, which blow at Oahu five-sixths of the year, while 

 at Raratonga they are constantly intermitted, and seldom continue half 

 the year : they exert less influence upon the climate in south than in 

 north latitude. 



The average daily range of temperature at Oahu is 12, whereas at 

 Raratonga it is but 5 ; the temperature of the water at the Hawaiian 

 Group is 81, while that at the Hervey Group is 75 : thus we have 

 two islands nearly similarly situated in geographical position, which 

 we find to differ but 0'19 in their mean annual temperature, 7 in their 

 average daily range, and 8 in their greatest difference. I regret that 

 there has not been any barometric observations made at Raratonga, 

 with which to compare the pressure at Oahu. The above results were 

 obtained from observations taken during the years 1837 and '38, at 

 both places, and are confined to the day observations, viz., 6 A. M., noon, 

 and 6 P.M., at Raratonga, and 7 A.M., 2 P.M., and 10 P.M., at Oahu. 



SYDNEY, NEW SOUTH WALES. Our stay at Sydney was from 

 the latter part of November till the end of December, 1839, and 

 the month of March, 1840. The weather, during the time of our 

 observations, was cloudy, with rain, the wind generally from the 

 eastward. The mean temperature for the month of December, 1839, 

 was 66'4, the extreme fluctuation 27, and the extreme daily varia- 

 tion 11. The mean standing of the barometer is 29-940 inches, and 

 its oscillation 1 - 810 inch; by the records of the Colony, the mean 

 annual temperature is G5'70. The seasons are considered but two, 

 summer and winter, the former from October to February, the latter 

 from May to September : at Sydney these are marked by the preva- 

 lence of the winds : during the former, the easterly winds blow, while 

 during the latter, they come from the southwest; in March and April, 

 as well as September and October, the winds are variable. The ther- 

 mometer seldom falls below 40, or ranges above 78 during the 

 winter ; in summer its range is from 54 to 91 : these temperatures 

 only apply to the east coast and to the day hours; therefore, although 

 we have the greatest heat, yet it cannot be considered the lowest tem- 

 perature : ice is seldom seen at Sydney. More recent observations, 

 kept at the South Head, at Port Jackson, make the temperature a 

 little different ; but even these latter observations do not include the 

 most important minimum hour of the night, and are, therefore, still 

 only approximate. At Port Philip, on the south coast, the thermo- 

 meter in the winter descends to 35, and rises to 65 : in summer its 



