19 PHILOSOPHICAL SOCIETY OF WASHINGTON. 
gence, an enthusiastic student in geology and botany, a companion 
and guide of several botanists in their early explorations of the 
southern Appalachians, and a farmer by profession. He died in 
1882, at the ripe old age of 87. 
He states that in the valley of the Little Tennessee river, in 
Macon county, lying about 2,000 feet above tide water, when the 
thermometer in the morning indicates a temperature of about 26°, 
the frost line extends about 300 feet in vertical height, but that then 
comes a belt extending about 400 feet in vertical height up the 
mountain side, within which no frost is seen, delicate plants remain- 
ing untouched. Above this, frost again appears. So sharp is the 
dividing line that sometimes one-half of a shrub may be frost 
killed, while the other half is unaffected. 
A small river, having its source in a high plateau 1,900 feet above 
this, runs down into this valley, breaking through three mountain 
barriers, and consequently making three short valleys, including 
the plateau, rising one above the other, each of which has its own 
vernal zone, traversing the hillsides that enclose it, and each 
beginning at a lesser elevation above the valley, as the valleys 
mount higher in the atmosphere, so that around the plateau, a 
beautiful level height, containing 6,000 acres of land, aud lying 
3,900 feet above tide water, the lower edge of the thermal belt is 
not more than 100 feet above the common level of the plateau. 
Not only does vegetation within this zone remain untouched by 
frost, so that the Isabella, the most tender of all the native grapes, 
has not failed to produce abundant crops in twenty-six consecutive 
years, but mildew, blight, and rust, which often attack vines in the 
lower valleys, are here unknown, while the same purity and dry- 
ness of the air which favor the grape, make this a refuge for the 
consumptive, as diseases of the lungs have never been known to 
originate among the inhabitants. 
Mr. McDowell adds: “The thermal belt must exist in all coun- 
tries that are traversed by high mountains and deep valleys, and 
the only reason why its visible manifestations are peculiar to our 
southern Alleghanies, is the fact that their precocious spring vegeta- 
tion is sometimes killed by frost, while the same thing does not 
happen in the mountains further north.” 
These statements are corroborated by similar testimony respect- 
ing another such belt along the Tryon mountain range in Polk 
county, N. C.; the specific claim being that such a belt is found 
