THE BLUE-RIDGE, WARM-SPRING, S:c. 217 



I beg leave however to mention fome circiimftances 

 which, as far as I am infonneJ, feem pccuhar to this 

 country. 



1. The atmofpherical changes in Europe, generally 

 caufe the mercury in the barometer to rife and fall three 

 inches, in the courfe of a year. 



2. In Williamfburg (Virginia) the greatefl change in 

 the courfe of a year has been obferved to be 1.86. 



2. At Mouticello, about 20 miles eail: of the Blue 

 Ridge, and about 500 feet high, the greateft variation in 

 nine months was* 1.2 1 : though the relative ch nges 

 were fimultancous with thofe at Williamfburg. 



4. During 11 days refidence at Staunton (1055 f^^t 

 high) and 29 at the Red Springs ( 1 5 i 2 feet high) the baro- 

 meter at the former place did not vary more than 0.40, 

 and at the latter only 0.20, while the thermometer varied 

 more than 30 degrees, and the weather was at the ex- 

 tremes of clear and dry, and cloudy with heavy rains. 



It feems therefore that the barometer is lefs fufceptible 

 of change in Virginia than in England, and ftill lefs as 

 you afcend among the mountains ; and it may not be 

 thought improbable that a regular meteorological journal 

 kept at the fame time in feveral places during a year, 

 would fhow a fort of gradation in thefe changes. 

 _. The lower part of the atmofphere, in addition to its own 

 gravity, fupportsall above it; its moifture is liable to ex- 

 pand prodigioufly from the rays of the fun refleded in 

 every direction, and other cafes of heat; and to be very fud- 

 denly condenfed by cold : The winds, impeded by many 

 obftacles, fuch as trees, rocks, and eminences of land, are 

 generally irregular and violent, like water rufliing over a 

 rude and rapid defcent ; while, in a fuperior region the 

 air glides Imoothly along like a current in the ocean. It 



■* Mr. Jefferfon's Notes, p. 83 and 85. 



feems 



