30 
CLIMATOLOGY. 
and the hill and table lands adjoining them are quite pro- 
ductive. 
SECT. Ill— CLIMATOLOGY. 
The cotton States of the South are situated mostly in 
the zone of climate designated warm. The peninsula of 
Florida, a small part of Louisiana and of Texas, are includ- 
ed in the hot zone. The warm zone embraces the coun- 
try between the isothermal lines of 70° and 60°. The 
mean annual temperature of five stations near the Atlantic 
coast is 65°, and of ten stations in the interior 63°. The 
climate of the interior is warmer in summer and colder in 
winter than that of the coast. 
In comparing the climates of the cotton regions with 
those of other countries, it is necessary to remember how 
much the best cotton districts are influenced by the Atlan- 
tic or the Mexican Gulf. The climate west of the Alle- 
ghany mountains is more mild than that under the same 
parallels in the Atlantic States, even to the extent of three 
degrees of latitude. 
This has been explained as caused by the warm air of 
the Gulf of Mexico being driven up the basin of the Mis- 
sissippi and that of the Ohio. The direction of the valley 
north and south no doubt favors the course of the south- 
ern winds ; while the regions of the Atlantic slopes, being 
transverse, oppose any such transmission. The majority 
of the places of which the mean temperatures have been 
adduced are on the sea-coast, and necessarily participate in 
the peculiarities of an insular climate ; that is, of seasons 
moderately contrasted. Still the difference between the 
hottest and the coldest month of the year is much greater 
than at Vera Cruz— that igf than 12° ; being, at Mobile, 
Galveston, and New Orleans, 27°.23, 29°.10, and 29°.96 
