32 Dr. Forry on the Climate of the United States, S^c. 



lakes and the coast of New England does to that of the third class 

 of the same division. The posts furnishing the meteorological 

 data of the Middle division are the following : — Fort Mifflin, near 

 Philadelphia, Washington City, Jefferson Barracks, near St. Lou- 

 is, Fort Monroe or Old Point Comfort, in Virginia, Fort Gibson, 

 in Arkansas, Fort Johnston on the coast of North Carolina, Au- 

 gusta Arsenal, Georgia, Fort Moultrie, Charleston Harbor, and Fort 

 Jesup, near Sabine River, Louisiana. The laws of climate devel- 

 oped in the preceding division, do not find so happy an illustra- 

 tion in this one ; for as the physical causes act less prominently, 

 the effects are less marked. These posts cannot be happily ar- 

 ranged into the tvsro classes of uniform and excessive climes, as 

 the majority of them are of a mixed character. Fort Mifflin and 

 Washington City do not properly pertain to either class, being in 

 a measure under the influence of the Atlantic, while the south- 

 western stations experience the powerful agency of the Gulf of 

 Mexico. As we proceed south, the seasons become, as a general 

 rule, more uniform in proportion as the mean annual temperature 

 increases. Although the thermometrical results given at Wash- 

 ington City, fairly place it in the class of excessive climates, yet 

 on following the same parallel westward, a still greater contrast 

 in the seasons is exhibited. Thus the difference between the 

 mean temperature of winter and summer at Jefferson Barracks, 

 notwithstanding it is about half a degree further south than Wash- 

 ington City, is i°-80 greater ; and on comparing Fort Gibson, Ar- 

 kansas, with Fort Monroe on the coast of Virginia, though the 

 latter is 1° 15' north of the former, the difference at Fort Gibson, 

 in the same respect, is 3°-69 greater. Fort Johnston, on the coast 

 of North Carolina, which is 0° 32' north of Augusta Arsenal, Geor- 

 gia, also exhibits a less extreme in the opposite seasons. Fort 

 Mifilin, near Philadelphia, shows a greater contrast in the opposite 

 seasons, (so all-powerful is the equalizing influence of large bod- 

 ies of water,) than any one of the following posts, all being from 

 two to seven degrees farther north, viz. Brady, Sullivan, Preble, 

 Niagara, West Point, Constitution, Wolcott, and Trumbull ; and 

 Washington City exhibits greater extremes than the three last 

 named. 



The general laws in reference to the difference between the 

 mean temperature of winter and spring, already revealed in the 

 Northern division, are here confirmed. Jefferson Barracks shows 



k 



