The Rev. R. Everest on Wells near Delhi. 303 



Dist.from Depth Depth rr. t 1 Temp. Temp. 

 1834. Locality. Delhi, to water, of water. * Fahr. of air. 



Miles. Feet. Feet. Feet. o 



A riil4'} Bahadurghur, " 2 ° 3 ° 3 ° 6 ° 75 ' 2 76 ' 2 



„ 1. Samplah 35 69 19 88 81-5 90-5 



„ 3. Moheim 65 96 39 135 82-8 95 



„ 4. Moordahal 75 96 44 140 75 89-5 



„ 5. Hausi 95 69 50 119 83-1 89 



„ 7. Hausi 115 45 160 79-8 67 



„ 9. Moheim 90 12 102 82 57 



Average 115 799 



The temperature of the water and air at Bahadurghur is the mean of two ob- 

 servations taken at an interval of fourteen days. 



Respecting the last table Mr. Everest says, the irregularities in 

 the temperatures may be explained by some of the wells being worked 

 for the purposes of irrigation, and therefore supplied by a current of 

 fresh water continually issuing from the ground ; whilst in those wells 

 which were still, the surface of stagnant water exposed to the air was 

 cooled by the evaporation dependent on so dry a climate. 



The general level of the country is said to be 800 feet above the 

 sea, and the temperature of Delhi, as determined by the author from 

 observations made during four years, to be 75 0, 78, or 7t 0, 64> Fahr., 

 taken as the mean between that result and another (73°*5) given in 

 the * Gleanings of Science.' If to this 1° # 8 were added for the depth 

 of the wells (115 feet), according to the rule which holds good in 

 Europe, the temperature would be 76° - 44', or something less than 

 that obtained by observation. Mr. Everest then proceeds to show, 

 according to the formula of Mr. Atkinson*, that the temperature 

 at the level of the sea, in the latitude of Delhi (28° 40'), should be 

 77°-84 (74°-64 + 3°'2 for the difference of 800 feet of altitude), and 

 that the temperature of Sincapore, in the second degree of north 

 latitude, is 80 o, 2, leaving, in comparison with that of the former 

 locality, only 2 0, 56 of temperature for above 26° of latitude. This 

 discrepancy, he is of opinion, maybe partly explained by Sincapore 

 being surrounded by the sea contiguous to the Pacific and Indian 

 Oceans, and cooled by perpetual showers, and Delhi being in the 

 midst of dry and burning plains. But, adds the author, the mean 

 annual temperature of Cairo, in 30° north latitude, and situated in 

 a dry and sandy continent, is not above 72°*5, leaving consequently 

 yet a difference to be accounted for, and which he conceives may be 

 owing to the tropical rains being limited west of the Indus to 23^° 

 north latitude, but extending in India even beyond 30° of latitude. 

 During the period in which the rain prevails, or from the 25th of June 

 to the 15th of September, the south-west monsoon blows nearly from 

 the equator and transports a large quantity of aqueous vapour ha- 

 ving a temperature from 77° to 81°, or that of the rain as it falls 

 and soaks into the earth, the evaporation being then very trifling. 

 The quantity of rain during the other nine months is so small that 

 it cannot counteract this effect, which, Mr. Everest says, may ac- 

 count both for the high temperature of the surface, and for the tem- 

 perature of the interior being greater than was to be expected. 

 * Transactions of the Astronomical Society for 1826, vol. ii. p. 137 et seq. 



