44 Mr. Caldcleugh’s Meteorological Observations 
On the 15th October I began to retrace my steps to Rio de 
Janeiro. Having left the barometer at Villa Rica, I made no 
kind of observations on the weather. The rains having com- 
menced, the roads were in some places in almost an impassable 
state, and I scarcely think the barometer could have escaped, 
from the many falls my mule experienced. 
I had imagined that the great humidity at Rio proceeded from 
the saline particles blown over by the sea breeze, but on exa- 
mining the foregoing register, it will be remarked, that there 
was more vapour in the air on the 19th and 23d of August, 
before the sea breeze had commenced, than on the preceding 
days. I have no doubt, therefore, that when the land breeze 
prevails all day, which sometimes, though fortunately rarely, 
happens, the most vapour is contained in the air; and it seems 
to me this must be the case. 
Beyond the Serra de Montigueira the track leaves the moun- 
tainous and thickly-wooded country, and crosses a high table 
land, where the pine is the only tree that seems to flourish. The 
height of this from the average of the barometrical observations 
above the sea, may be about 3720 English feet. Baron Hum- 
boldt gives the lower limit of the Mexican Pine (19 N. Lat.) at 
1150 metres = 3769 English feet. I have seen this species 
growing in still lower situations in Brazil, but certainly with not 
so much luxuriance. 
The means of the observations made at Villa Rica, are as 
follows :— 
Bar. 26.393—Attached and Detached Ther. 693°—Dew point 
65°, and grains of vapour in cubic foot 6.577. Its conse- 
quent height above the sea 3,969 feet. 
The mean quantity of vapour observed by Mr. Daniell, for the 
two years ending with the summer of 1821, was, grs. 3.652, not 
much more than half the mean at Villa Rica. The prevailing 
winds there were south and south-east. 
[ remarked invariably the barometer to stand lower, and the 
quantity of vapour more considerable, in the evening than the 
following morning. When overlooking some of the thick woods, 
it was curious to see the warm vapour ascending like smoke from 
