1839] 



On the Slatistics of Dukhun. 



155- 



With respect to the greatest diurnal, and the greatest monthly range 

 of the thermometer, the winter months have a range nearly in a quadru- 

 ple ratio to the'monsoon months. The latter have mostly the tempera=r 

 ture very equable, the diiference of the monthly means rarely exceeding, 

 3°, and the greatest diurnal range in five years only once amounted to< 

 13^ -6. The latter end of March, and April, and May are the hottest pe- 

 riods of the year, from the position of a nearly vertical sun, the intensi- 

 ty of whose influence is but slightly modified by the occasionally cloudy 

 weather: the temperature falls in June, and continues nearly stationary 

 until the end of September: it then rises in October, but falls at the end 

 of the month, until its annual minimum in December or January. It is 

 low the early part of March, but rises suddenly after the middle of the 

 month, occasioning a difference of 6° or 8° between the means of Feb- 

 ruary and March, which is more than double that of other consecutive 

 rnonths in the year. The rise in October is also sudden, but does not 

 occasion so great a difference of means as between February and March. 

 It will thus be remarked that the temperature does not follow the sun's- 

 declination, owing to the interference of the monsoon. 



Mohture. — A remarkable feature in the climate of Dukhun is the 

 small quantity of aqueous vapour generally suspended in the air, com- 

 pared with the proximate climate of Bombay and the coast, or even the 

 hilly tracts of the Ghats. My observations were made with Daniell's 

 hygrometer, and extended over several years. There is a gradual in- 

 crease of moisture in a cubic foot of air, from the most dry month, Feb- 

 ruary, until June and July. Hence the moisture remains nearly station- 

 ary until the beginning of October, when it diminishes somewhat rapid- 

 ly and regularly until February. The annual mean dewing point is. 

 greater at a. m, than at sunrise or at 4 p. m., but this docs not uniform- 

 ly hold good in each month of the year. In 1826, the highest dewing 

 point w^as at four o'clock on the 2lst October, being 76°-, temperature of 

 theair84°-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 dri- 

 est state of the atmosphere, as a dewing point of 45° in November, with 

 a temperature of 87° at 4 p. m., gave only 3'5S7 grains. 



The most moist month was July ; the mean weight of water in a cubic 

 foot of air w^as 8*775 grains, and the point of saturation was only 4°'85 

 Tom the dewing point. The greatest monthly range of the dewing 

 )oint was, in October, 30°, and the smallest range, 7°, was in July and 

 \ugust. The monthly range was not coincident with the movements of 



