184 LIEUT.-COLONEL SYKES ON THE ATMOSPHERIC TIDES 



temperature 79°; a cubic foot of air containing 10-049 grains of aqueous vapour. 

 This may be looked upon as great, the temperature of the air at Poona being rarely 

 7&° Fahr. when it absolutely rains. 



A very dry state of the atmosphere occurred in January, the dewing-point on the 

 4th of the month at sunrise being obtained three degrees below the congelation of 

 water, temperature 62°. A cubic foot of air at this observation contained 2*146 grains 

 of water ; but this did not indicate the driest state of the atmosphere, the dewing- 

 point from the point of saturation being 33°, while on the 5th of December it diifered 

 46°, the dewing-point being 37°, and temperature of air 83°. 



As in the preceding year, the smallest range of the hygrometer is found in July and 

 August. From these months there is a rapid increase in the range until January, 

 when the greatest monthly range occurs, namely 38°. December has also a very high 

 range of 32°. The extreme range in the year amounts to 47° ; that is to say, from a 

 dewing-point of 29°, temperature 62°, in January, to 7^"", temperature 79°, in June. 



In 1827, as in the preceding year, there is a limited conformity in the range of the 

 hygrometer to that of the thermometer. The monsoon months have the smallest 

 range, the cold months the greatest, and the remaining months a range between 

 those already noticed. 



In 1828 my hygrometric observations in Dukhun extend through three months 

 only. In these months, as in the preceding years, there was more aqueous vapour in 

 the atmosphere at 9J a.m. than at sunrise or at 4 p.m. In February of this year the 

 lowest dewing-point ever recorded on the general level of the country took place, 

 being 5° below the freezing-point, namely, 27° Fahr., the temperature of the air being 

 57°'50, and a cubic foot supporting 2*032 grains of aqueous vapour. Even this is not 

 the lowest degree of absolute dryness remarked in the Dukhun, as on the hill fort 

 of Loghur, on the 12th of March, the dewing-point, although 27° Fahr., took place 

 when the temperature of the air was Q7° Fahr. : consequently, a cubic foot of air 

 contained only 1*995 grains of aqueous vapour instead of 2*032 grains. A yet further 

 degree of dryness occurred on the 1 6th of February at 4 p.m., at Downd, near Pair- 

 gaon, on the.Beema river, when the dewing-point was 61° from the point of satura- 

 tion, the former being 29°, and the temperature of the air 90°. The highest dewing- 

 point in the three months of winter occurred at 9 J a.m. in January, namely, 69° Fahr., 

 the weight of moisture being 7*988 grains; a state of the atmosphere which may be 

 looked upon as very unusual in that dry month. The range of the dewing-point in 

 January (37°) approximates very closely to that of the same month in the preceding 

 year. The same observation applies to the month of March ; but there is a discre- 

 pancy with respect to February. 



In 1 829 my observations extend from June to December, inclusive : the mean of 

 the three periods of the day is nearly identical for the monsoon months, viz. 69°*03, 

 69°*77 and 70°*06 : the maxima, 77°, occurred in June and October at 4 p.m. ; the 

 minima all in October, 58° at sunrise, 50° at 9j a.m., and 44° at 4 p.m. The mean 



