IN THE SOUTHERN HEMISPHERE. 
435 
The thermometers, employed for observing the temperature of the air and of the 
surface of the sea, were frequently tested by immersing them in melting snow, and the 
necessary corrections have been applied. The thermometers were found to have very 
little index error. The temperature of the surface of the sea was obtained by drawing 
up water in a small canvas bucket and immersing a thermometer immediately into it. 
The directions of the wind are the true ones, i. e. the observed compass direction 
corrected for the declination. The force of the wind and the state of weather were 
recorded according to the system drawn up by Captain Beaufort for the use of the 
Royal Navy : — frequent attempts were made to observe the force of the wind by 
means of one of Lind’s gauges, but owing to the rolling motion of the ship it was 
found impossible. 
The observations in the Pagoda show a lower barometer within the Tropics than a 
little beyond them; the mercury rising from latitude —20° to about —35°, where it 
stood at 30' 15. 
From latitude —35° to —56° the barometer fell rapidly, the difference being l - 054 
inch. The descent of the mercury with the increase of latitude did not appear to 
extend beyond —56°, as in the forty days during which the Pagoda was between 
— 60° and —67°' 5, the mean height of the barometer scarcely differed from the mean 
corresponding to —56° 21'. 
The gaseous pressure presents similar features, rising from —20° to —35°, thence 
descending to —56°, and remaining nearly constant from —56° to —67°. The differ- 
ence between lat. —35° and lat. —56° amounts in this case to 0 - 78 inch. 
No influence of longitude on the barometer is deducible from these observations, 
extending from 0° to 1 20° East. 
For the purpose of comparing these results with the inferences which have been 
derived from previous observations, I have added an abstract of the conclusions 
drawn from the observations discussed in Dr. Adolph Erman’s work*, which has 
been communicated to me by Lieut.-Colonel Sabine. 
“ From a parallel very near the equator, the pressure of the atmosphere, measured 
by the barometer corrected for gravity, increases both northward and southward to 
a little beyond the outer limit of the trade winds ; beyond this limit the pressure 
decreases, at first slowly, but much more rapidly after passing the 50th parallel. The 
maximum of pressure occurs at about 35° in each hemisphere. The decrease from 
the maximum in the direction of the Pole has been found in the southern hemisphere 
to continue as far as the parallel of Cape Horn ( — 55°*5), where the low pressure cor- 
responds with that observed in the northern hemisphere at Kamtchatka and Sitka, 
which are nearly in the same latitude. 
“ The dry air has also a minimum zone within the inner limits of the trades ; the 
increase from thence in both directions is more rapid and considerable than that of 
the pressure of the gaseous and aqueous atmospheres united, and the gaseous max- 
imum in both hemispheres is obtained in a higher latitude (about 45°). The pressure 
* Ueber Meteorologische Beobachtungen bei einer Seereise um die Erde. 
