234 SEVENTH REPORT—1837. 
the coast, or even the hilly tracts of the Ghats. My obser- 
vations were made with Daniell’s hygrometer, and extended 
over several years. There is a gradual increase of moisture in 
a cubic foot of air, from the most dry month, February, until 
June and July. Hence the moisture remains nearly stationary 
until the beginning of October, when it diminishes somewhat 
rapidly and regularly until February. The annual mean dew- 
ing point is greater at 94 A.M. than at sunrise or at 4 P.M., but 
this does not uniformly hold good in each month of the year. 
In 1826, the highest dewing point was at four o’clock on the 
2lst October, being 76°, temperature of the air 84°°5, a 
cubic foot of air holding 9°945 grains of water. The lowest 
dewing point was on the 4th December, at sunrise, being 44°, 
temperature of the air 56°, a cubic foot of air containing 3°673 
grains of aqueous vapour; but the lowest dewing point did 
not indicate the driest state of the atmosphere, as a dewin 
point of 45° in November, with a temperature of 87° at 4P.M., 
gave only 3°587 grains. 
The most moist month was July; the mean weight of water 
in a cubic foot of air was 8°775 grains, and the point of satu- 
ration was only 4°85 from the dewing point. The greatest 
monthly range of the dewing point was, in October, 30°, and 
the smallest range, 7°, was in July and August. The monthly 
range was not coincident with the movements of the barometer 
and thermometer; but there were curious approximations. 
The extreme dewing points differed 32°. The dewing point 
has been as high as 76°, temperature of the air 79°, a cubic 
foot of air containing 10°049 grains of aqueous vapour; but 
this is a rare occurrence. An instance occurred of the dewing 
point being obtained at 3° below the point of the congelation 
of water, the temperature of the air being 62°, and a cubic foot 
of air holding 27146 grains of water. There is also an instance 
of a dewing point, in February, 1828, being 61° below the 
temperature of the air, viz., from 90° to 29°, but I never after- 
wards succeeded in determining anything like so great: a 
depression. 
In January, 1827, there was a range of the dewing point of 
38°, and the extreme range of the year was 47°, viz., from 29°, 
temperature 62°, in January, to 76°, temperature 79°, in June. 
In 1829, the mean dewing point for the monsoon was 69°'62, 
temperature 75°'83 ; the cubic foot of air containing 8°191 grains 
of water. In 1830, the observations are only complete for 
9-10 a.m.; the mean dewing point was 61°°9, temperature 
78°°4, and a cubic foot of air contained 6°351 grains of water ; 
the extreme range of the hygrometer was 47°, the lowest 
