AND RIVERS OF INDIA AND EGYFr, ETC. 



131 



same oceans, near the land, and in narrow seas, the range between the extremes is 

 much greater than 3°-4. In the Red Sea, from the Straits of Babeiniandel to the 

 tropic of Cancer, I found it, in the month of May, to be 6^ viz. from 82° to 88°; and 

 in the Indian Ocean, from lat. 12° to 19°, so much as 8°'5, viz. from 78° to 87°-5. 

 In the Straits of Malacca, in lat. 2° N., it ranged from 80° to 85°'2. 



On some parts of the west coast of India (where 123J inches of rain falls during the 

 year), during the monsoon, the surface of the sea is considerably cooled by the freshes 

 from the numerous rivers and streamlets that descend from the lofty mountains of 

 the Ghauts. Off Honawer, lat. 14° 16' N., the temperature of the sea during the 

 dry season was 85°-5. During the monsoon it fell to 79°; average temperature of 

 rain water at the time, 75°7 ; of rivers, 7^°- From its inferior specific gravity, the 

 fresh muddy water from the hills floats on the surface of the sea to considerable 

 distances, without being intimately blended. In the depth o^ the monsoon, near 

 Mangalore, in 1839, the water was observed to be nearly fresh a mile off the coast; 

 and I have seen the Mediterranean discoloured by the turbid inundation of the Nile 

 to a distance of nearly forty miles from the Damietta embouchure. 



Meaii Temperature in India. — Colonel Svkes, in his statistics of the Deccan, has 

 already noted one remarkable feature touching the mean temperature of places at 

 elevations on 4;he table-land of India, namely, that it is much higher than the mean 

 for the same places, calculated agreeably to Mayer's formula. To the instances he 

 has cited of this fact, of places on the plateau of the Deccan, may be added the fol- 

 lowing, occm-ring on the table-land of South India. 



Among the principal causes of this differential height of temperature, — a difference 

 more remarkable when compared with the indications afforded by the improved for- 

 mulae of Brewster, D'Aubuisson and Atkinson, — may be enumerated the physical 

 aspect and extent of the elevated plains on which these places stand, — the rapidity 

 with which the drainage water passes off, and consequent little evaporation, — the 

 comparatively fiat, or gently undulating surface, — its bareness of vegetation during 

 great part of the year, — the non-influence of alternations of land and sea breezes, by 

 which places near the sea are cooled, — the partial influence of the monsoon and 

 scantiness of rain, — the favourable conditions of the atmosphere for irradiation, and 

 the capacity of the soil for imbibing and giving out the solar heat. The temperature 

 of the granitic soil in the vicinity of Bellary, at 2 p.m., in May, reached 121°; that of 

 the Regur, or black soil, 122°-5 : the temperature of the air in the shade, 95°-5 : at 

 midnight the temperature of the black soil was still so high as 86°; temperature of the 



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