124 Mr. Colebrooke’s Meteorological Observations 
scends to a less proportion; but sometimes at noon (the weather 
being fair) rises to a sixth, and even a fifth part. 
Besides the equatorial zone, or tract intervening between the 
trade-winds in the vicinity of the equator, where a nearly equable 
temperature and uniform humidity prevail, other belts of both 
equable temperature and humidity are indicated; for transitions 
are not always regular, even within the limits of unvaried winds. 
Some less distinctly marked, may for the present be passed 
by; but, on the exterior side of either tropic, for a breadth of 
five or six degrees of latitude towards the further bounds of 
the trade-winds (lat. 28° or 30° N. and S.), there seems to be 
such a zone strongly pronounced. In the southern one, the 
mean temperature of the sea was 73° in November, (beginning 
of summer); and 693° in April (autumn): the point of dew at 
the latter period was almost as uniformly 634°: the tem- 
perature of the air scarcely deviated more than a degree from a 
mean somewhat above that of the sea in the first season, and a 
little below it in the second. 
In the correspondent northern zone, the mean temperature 
of the sea was nearly 74° in October, and 72° in May, a little 
below that of the air in the first mentioned season, and above it 
in the last. The point of deposition of dew was about 673° in 
the latter season, fluctuating 1° on either side of that mean. 
At the position, where observations taken by me at different 
seasons, admit of direct comparison; that is, where the two 
routes intersect ; which was about lat. 3° N. and long. 22° W.; 
the temperature was found, in the middle of November, (with a 
south-east trade-wind), of the sea, 79°; of the atmosphere, 
803°; increasing to 824° at noon; and it was in the middle of 
May, (with variable winds and calms,) of the sea, 83°; of the 
atmosphere, 80° ; rising to 83° at noon. 
Here the contrast is between the temperature of the sea at 
two seasons; that of the air being nearly the same at both. 
The sun was at both times increasing his distance towards a 
solstice. The effect then upon the heat of the sea’s surface is 
to be ascribed to the cooling power of a dry wind in one case, 
