AND METEOROLOGY OF DUKHUN. 183 



weight of moisture in the air, allowing for the correction for increased temperature, 

 than at sunrise or 9 J a.m. From June to December, inclusive, the mean dewing-point 

 was 66°75, mean temperature 77°'23, a cubic foot of air containing 7*455 grains of 

 water. 



The highest dewing-point recorded in Dukhun in 1826, occurred at 4 o'clock on 

 the 2 1st of October, being 76° ; temperature of air 84°*50 ; a cubic foot of air con- 

 taining 9-945 grains of water. The lowest dewing-point occurred at sunrise on the 

 4th of December, being 44° ; a cubic foot of air containing 3 '673 grains of aqueous 

 vapour at a temperature of air of 56°. But the lowest dewing-point did not indicate 

 the driest state of the atmosphere, as a dewing-point of 45° in November, with a tem- 

 perature of 87°, at 4 P.M. gave only 3*587 grains of water in a cubic foot of air. The 

 most moist month was July, the mean weight of water in the atmosphere in a cubic 

 foot of air being 8*775 grains, and the point of saturation 4°*85 from the dewing-point. 



The greatest monthly range of the dewing-point was in October (30°), and the 

 smallest range in July and August (7°). An inspection of the monthly ranges will 

 show that they conform to a limited extent only with the ranges of the barometer 

 and thermometer. From June to December inclusive, the extreme dewing-points 

 differed 32°. 



In 1827 my hygrometric observations are complete for the whole year. The fol- 

 lowing are the results. In the means for the months, as in 1826, with the exception 

 of part of April and the months of May and October, the 9 J a.m. means give a greater 

 quantity of moisture in the atmosphere than at sunrise ; the mean for the year at half- 

 past nine having a dewing-point of 60°*74, temperature of air 78°'50, the cubic foot of air 

 containing 6*140 grains of moisture ; and the yearly mean at sunrise having a dewing- 

 point of 59°*26, temperature 71°'20, and the cubic foot of air containing 5*940 grains 

 of aqueous vapour. In part of April and in the month of August only does the mean 

 at 4 P.M. give a higher dewing-point and a greater quantity of vapour in the air than 

 at 9j A.M. and at sunrise. In August we find a cubic foot of air at 4 p.m. containing 

 8*692 grains of aqueous vapour. 



The quantity, however, is only great in relation to the quantity contained in the 

 air at other hours of observation in the same month, and it will not bear comparison 

 with the mean quantity held suspended at other periods during the monsoon ; for 

 we see by the Table, that in June, at 4 p.m., a cubic foot of air held 8*883 grains of 

 water, and the other hours of observation had still larger quantities: nevertheless the 

 monthly mean indicates August being the most moist month in 1827; for although 

 a cubic foot of air contained only 8*574 grains, and June held 8*931 grains of 

 water in a cubic foot of air, yet the difference between the dewing-point and the tem- 

 perature of the air in August was only 5°*18, while in June those points were 7°'51 

 from each other : the air in August, therefore, was nearest to saturation ; but the re- 

 maining months of the monsoon differ very slightly from these results. The highest 

 dewing-point in Dukhun, in 1827, occurred at 4 p.m., on the 13th of June, being 76°, 



