240 On the Height of the 



In all situations where it is practicable to make a cold air flue, 

 of considerable length under ground, the advantage is well worth 

 securing. I have found by experience that a cold air-flue of 50 

 yards in length is capable of cooling the air in summer to about 

 an arithmetical mean between the temperature of the air and the 

 earth, and a similar advantage is produced by the eai'th warming 

 the air in the winter season. The shape of the cold air-flue 

 should be such as to present the greatest possible surface ; the 

 very contrary being essential to the best construction of flues for 

 the warm air. 



These facts will successfully lead to the means of cooling 

 buildings in the tropical climates, and of warming the air when 

 the winter's cold is much below the temperature of the earth. 



Great Russel- street, Bloomshury, May, 1821. 



Art. II. On the Height of the Dhawalagiri, the White 

 Mountain of Himalaya. Bi/ H. T. Colebrooke, Esq. 



[Communicated by the Author.] 

 In an essay on the height of the Himalaya Mountains, which 

 was inserted in the 12th volume of Researches of the Asiatic 

 Society, I offered reasons for the opinion of their great eleva- 

 tion : relying especially on the measurement of the White 

 Mountain, emphatically so named, which towers above the rest 

 of the snowy peaks seen from the plains of Hindustan. Its 

 height was computed, from three sets of observations, taken by 

 Captain Webb, at 27,551 feet above the observer's stations in 

 Gorakhpur ; or 27,677 feet, making that allowance for refraction, 

 which was found to bring the result of the several observations 

 nearest to agreement. Even assuming all errors to be on one side, 

 and in the extreme, it would appear to be 26,862 feet at the 

 lowest computation. But such extremity of errors is hardly 

 presumable ; and considering the supposition of compensation 

 of errors, and ordinary rather than extraordinary refraction, to 

 be more likely correct, the inference was that the White Moun- 

 tain may be about 27,600 feet above Gorakhpur, or nearly 

 28,000 feet above the level of the sea. 



