AND METEOROLOGY OF DUKHUN. 181 



nuary (65°-90), was only 17°-38. In 1827 January was the coldest month, and the hot- 

 test was April, their mean difference being 1 4°'06. In 1828 the coldest month was De- 

 cember and the hottest May, their difference 15°'41. In 1829 March was the hottest 

 and November the coldest, their difference 13°'66. The greatest diurnal range in 1826 

 was 37°-30, on the 5th of March, from 50°*5 to 87°-8. In 1827 it was 39°-5, on the 12th 

 of December, from 49°-5 to 89°. In 1828 it was 34°-8, on the 16th of February, from 

 56° to 90°*8. In 1829 the maximum diurnal range was 37°'5, in December. The least 

 diurnal range in 1826 was on the 22nd of August, amounting only to 0*60. In 1827 

 it also occurred in August (9th), being only 0°-40. In 1828 the minimum range was 

 on the 18th of October, amounting to 0°'40 ; an unprecedented circumstance in that 

 month. In 1829 the minimum range was 0°-60, in August. In 1830 it was 0°'5, in 

 July. 



With respect to the greatest diurnal and the greatest monthly range, of the ther- 

 mometer, the winter months have a range nearly in a quadruple ratio to the monsoon 

 months, June, July, August, and September. The latter have mostly their temperature 

 very equable, the difference 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 months in the year, from the position of a nearly 

 vertical sun, the intensity of whose influence is but slightly modified by the occasion- 

 ally cloudy weather in May preceding the monsoon. 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 February and March, which 

 is more than double that of other consecutive months in the year. The rise in 

 October is also sudden, but does not occasion so great a difference of means as be- 

 tween 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. 



My thermometrical observations in Dukhun were made upon levels ranging from 

 1400 feet above the sea to 4500. At the latter height, however, they were very limit- 

 ed in number, and beyond the levels of 1600 and 2200 feet they may be considered 

 to have scarcely any sensible influence upon a mean temperature struck for tracts 

 traversed between 1900 and 2000 feet. For instance, the mean temperature of Ah- 

 mednuggur in 1828 (1900 feet). Dr. Walker determined to be 78° Fahr., and 

 my mean temperature for the country I traversed in that year was 77°'93. In 1827 

 it was 77*25 ; and in 1826, when my researches were a good deal confined to the 

 hilly tracts, the mean temperature was 76°-46 ; and in 1829 the mean temperature was 

 reduced to 74°*8, three months' observations of the year having been taken at 3943 

 feet above the sea, and one month's observations at 2416 feet. One fact is very re- 

 markable ; the observed mean temperature of places on the table land of India is 

 much higher than the calculated mean temperature of the same places agreeably to 



