INTRODUCTION. 



mi tin- >;init' plate a diagram of tin- I!eliet"s track, the year before, and 

 refer to the Peacock's track and observations on Plate XX III., Ap- 

 pendix, the year after, which were nearly over the same course; and. 

 the depression of their barometers being reduced to the same standard, 

 they very nearly correspond. The diagrams also point out the changes 

 that took place in the teiujwrature of the air and water, and show that 

 they attain their maximum k-tween ~>" and 7 south latitude, in these 

 longitudes. It also will be seen that the thermometer indicates tin- 

 same temperature in the latitude of 21 north, that it has in I;") south 

 latitude. In passing through the licit of ocean comprised within the 

 10th degree of latitude on either side of the equator, we found t In- 

 mean degree of moisture to be -868, and the solar radiation 18. We 

 lost the southeast trades in 7 south latitude; they afterwards conti- 

 nued variable, lasting but a few hours from any one direction. When 

 in latitude 3 south, we had a heavy fall of rain, 5'2 inches, the tem- 

 perature of which was (ili. air 70; the upper stratum of clouds, after 

 i-ed. \\as seen moving from the east-northeast. 



The variable winds accompanied us until we reached the latitude 

 of 8 north, when we met the northeast trades. During this pa-sa.ue 

 of 43 days, the maximum temperature was 88, minimum 73 ; the 

 greatest oscillation of the barometer -list) in. 



The other \essels of the squadron made the pas>ai:e at the same- 

 time, and all their observations tend to confirm those of the Vincennes. 



HAWAIIAN ISLANDS. Our observations at these i.-lands continued 

 through a space of six months, from Septemlier to April. 1X40-41. 

 The first two months of this time they were made on the Island of 

 Oahu. and the last three on Hawaii, the former on the leeward and the 

 latter on the \\ indward side. These will be found projected in the dia- 

 grams, on Plate XIV.. pap- 140. The mean temperature in the first 

 |M-riod at Honolulu (Oahu), was 78'01, varying from 70 to 89, and 

 during the last at Hilo (Hawaii). 70-ii',l . and varying from .">7 to 82. 

 The oscillations of the barometer are greater than in south latitude, and 

 more tlnctnatinu. being --"ilO in. The mean standing of the barometer 

 \\a> 'J'.i '.i?.; in. The column generally rises with the northwest winds, 

 and is depreed | IV the northeast. The tropical hours for 47 days 

 (hourly observations) correspond to.">h.:;i m. \.M..'.) h. :!(i in. A.M. ,3 h. 

 1 '2 m. i-. M., h. :;il m. i-. M. The mean annual temperature, by tin- ol>- 



-eiAations kept for >e\eral years at Hi lulu, is 7-VS, that of a sunken 



thermometer, .-ix and a half feet deep, gave M'-'i '.* The diurnal vari- 



I MtlaloMtOM ml f'*r thi* :ip|i:irriit ilix Tr|,;mry Ix-twccn what the Imrirtl 



lli> rni'. m.-t.T pvr, and tlir in .-in annual (riii|>rraturr t'"r >c\cral \ .':ir- ; llir (licnnnnirtcr 



