AND METEOROLOGY OF DUKHUN. ']8o 



dewing-point for the monsoon was 69°-62, temperature of the air 75°-83, the cubic 

 foot of air containing 8* 191 grains of water; the maximum diurnal range 6° in Sep- 

 tember, and the maximum monthly range 8° in June and September. In October 

 the mean dewing-point fell to 65°*83, temperature 78°' 13. The maximum diurnal 

 range increased to 26°, and the extreme monthly range was 33°. In 1830 the ob- 

 servations are only complete for 9 — 10 a.m. : the mean dewing-point was 61°-9, mean 

 temperature 78°'4, and a cubic foot of air contained 6*351 grains of water : the ex- 

 treme range of the hygrometer was 47°, and the lowest dewing-point 31°, tempera- 

 ture 50°, in December. An inspection of the tables Nos. 17 — 21 will show the gradual 

 increase of moisture in a cubic foot of air from the most dry month, February, until 

 June or July. Hence the moistness remains nearly stationary until the beginning of 

 October, when it diminishes, somewhat rapidly and regularly, until February. 



It might be supposed that the hottest months in the year, March, April, and May, 

 would also be the driest ; but such is not the fact. The powerful action of the sun 

 on the ocean in the middle of March raises a large quantity of aqueous vapour, which 

 continues to increase in the ratio of the sun's progress north. The westerly winds 

 waft this aqueous vapour inco Dukhun : much of it is arrested by the Ghats and 

 hilly tracts eastward of those hills ; accounting for the sensible moistness of the air, 

 the frequent night-fogs, and deposition of dew on this line in the end of March and 

 in all April and May. The supply of moisture diminishes in proportion to the 

 distance eastward from the sea to the limits of the Coromandel coast monsoon : we 

 in consequence find the Ghats, Poona, Ahmednuggur, and the Bala Ghat, all with 

 very different dewing-points in the hot months. 



My visits to Bombay on public duty in successive years, in the hot and cold 

 months, enabled me to determine, in the most satisfactory manner, with the aid of 

 I Daniell's hygrometer, the usual surcharged state of the air of the coast with mois- 

 ture, and its ample means of supplying the interior table land with aqueous vapour. 



In April and May 1826, in Bombay, the monthly mean dewing-points were respec- 

 tively 72°'84 and 75°'59, temperature 83°-48 and 84°-52, a cubic foot of air holding 

 8*988 grains, and 9*748 grains of water suspended ; whilst July, the most rainy 

 month during the monsoon at Poona, had only a mean of 8*775 grains of water 

 suspended. In 1827 the mean of ten days' dewing-points in Bombay in April gave 

 10*243 grains. The greatest mean quantity at Poona during the monsoon in June 

 was only 8*931 grains of water in a cubic foot of air. In 1828 I was enabled, in the 

 month of March, to establish comparisons, derived from observations on consecutive 

 days, between Bombay, the top of the Ghats, the hill fort of Loghur, and Poona. 

 At' 4 P.M. in Bombay, on the 10th of March, a cubic foot of air held 11*205 grains of 

 water. At Poona, at the same hour on the 14th of March, a cubic foot of air con- 

 tained only 2*273 grains of water. At Bombay, on the 10th, at sunrise and at 

 9i A.M., the dewing-points were respectively 72° and 71°, temperature 75° and 81°*50; 

 a cubic foot of air containing 8*873 grains at the former hour, and 8*487 grains of 



MDCCCXXXV. 2 B 



