70 Barometric Measurement of Sugar-loaf Mountain, 



is under 3000 feet : on returning from the summit, the baromfer 

 ter was replaced three feet above the floor of the house, and 

 allowed to remain until the mercury should have acquired the 

 temperature of the air, when, at li> 30«n P.M., its height was 

 27.937 in., air and mercury 72°, point of deposition 68°, and 

 in the lower barometer 30.137 in., air and mercury 84.5, point 

 of deposition 71°, whence the height of the floor of the Moun- 

 tain-house results 2219 feet above the sea, being three feet less 

 than the first measurement. The mean, consequently, or 2220.5 

 feet, is considered the correct elevation. 



Height of the Block-hcnise at Fort George, Trinidad. — Octo- 

 ber 9th, 1822, at 8h 30™ A.M., a barometer, 41 feet above the 

 foundation of the Block-house, stood at 29.000 in,, the air and 

 mercury being 76.5, and the point of deposition 76.5 also, with 

 slight rain. The corresponding height of the barometer, at the 

 same time, in the Protestant church in Port Spain, 20 feet 

 above the sea, was 30.058 in., air and mercury 82°, and the 

 point of deposition 77°. Whence the foundation of the Block- 

 house would appear 1067 feet above the sea. 



Height of Mr. Robert Chisholtn's ho^/.se, in the Port-Royal 

 Mountains, Jamaica. — October 3 1st, at 4'' SO-" P.M., a barome- 

 ter, suspended against the wall of Mr. Chisholm's house, 2 feet 

 above the ground, stood at 25.967 in., the air and mercury being 

 68.5, and the point of deposition 68.5 also; and on the 2d of 

 November, at 6 A.M., at 25.963 in., the air and mercury 65°, 

 and the point of deposition 60°. The corresponding observa- 

 tions at Port Royal, at the same hours, 8 feet above the sea, 

 were — 



Oct. 31,— Bar. 30.007; Air, 82.5; Merc ., 84.5 ; Dew point, 77 

 Nov. 2, „ 30.023 78. 78. 72 



"Whence the height of the ground on which Mr. Chisholm's 

 house stands, results respectively, 4087.9 feet, and 4072.7 feet, 

 the mean being 4C80.3 feet above the sea. 



All the observations at heights were made with the same 

 portable barometer ; ■^^, therefore, is added throughout to the 

 barometric differences on account of the ratio of the diameters of 

 the tube and cistern. The height of the column of mercury, in the 



