568 FOURTH REPORT — 1834. 



temperature of Calcutta and that of Mhon, giving 480 ft. 

 nearly to each 1° of temperature. 



Ahmednuggur, in the Deccan, in lat. 19° 6', and 1900 feet 

 above the sea, has a mean temperature, as determined by Dr. 

 Walker, of 78° Fahr., while the calculated mean temperature at 

 the level of the sea is 78°'6, giving a difference of 0°*6 of a 

 degree, for a difference of level of 1900 ft. The mean tem- 

 perature at Col. Sykes's residence in Poona, lat. 18° .SO', eleva- 

 tion above the sea 1823 ft., was 77°*7. The calculated mean 

 temperature at the level of the sea is 78° '94, giving 1° for 

 1471 feet. 



The mean temperature of a spring in the excavated caves in 

 the Hill-fort of Hurreechundurghur, lat. 19° 23', at 3900 ft. 

 above the sea, was 69°*5 Fahr. The calculated mean tempera- 

 ture at the level of the sea, 78° '45 ; giving 1 ° Fahr. for 435 ft. 



The mean temperature of Seringapatam, at 2230 ft. above 

 the sea, is 77°*06, corresponding nearly to the mean of Poona 

 and Ahmednuggur, although the latter places are between 

 6° and 7° of lat. further north, and their levels nearly the same. 

 The calculated mean temperature of Seringapatam, at the level 

 of the sea, is, by Meyer's formula, 81°"77; by Brewster's amended 

 formula, 79°"9, and by his genei-al formula, including the con- 

 sideration of two poles of maximum cold, (see Trans, of the 

 Roy. Soc. Edinburgh, vol. ix.) 76°*5o. In the first case the dif- 

 ference of temperature corresponding to 2230 ft.=4°*71, (or 1° 

 for 473 ft.) ; in the second, 2°-84 (or 1° for 785 ft.); in the third 

 the result is negative. 



In an observation at a height of 8500 ft., the value due to 

 each degree of alteration of temperature corresponds very 

 closely with the general result (332 ft.) adopted by Professor 

 Forbes in his Report on Meteorology. 



The mean temperature at the equator has been stated at 

 81^°: the result of 21 years' observations at the Observatory of 

 Madras, more than 10° from the equator, situated on an open 

 beach, has determined the mean temperature of that place to 

 be 81°"69; and in general, Col. Sykes concludes that the ob- 

 served mean temperatures in India everywhere exceed those 

 given by calculation. By the result of several years' observa- 

 tions, he has found that the mean temperature of the hour of 

 the maximum diurnal atmospheric tide (between 9 and 10 a.m.) 

 is equal to the mean temperature of the year in India. The 

 heights of places mentioned in this communication were deter- 

 mined barometricallv. 



