Dr FoiTy on the Climate of the United States. 85 



a degree farther south then Washington City, is 1°.80 

 greater ; and on comparing Fort Gibson, Arkansas, 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, 

 Georgia, also exhibits a less extreme in the opposite seasons. 

 Fort Mifflin, near Philadelphia, shews a greater contrast in 

 the opposite seasons (so all-powerful is the equalizing influ- 

 ence of large bodies of Avater), than any one of the following 

 posts, all being from two to seven degrees farther north, 

 viz. Brady, Sullivan, Preble, Niagara, West Point, Constitu- 

 tion, Wolcott, and Trumbull ; and Washington City exhibits 

 greater extremes than the three last named. 



The "-eneral 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 

 shews a greater inequality than Washington City, and Fort 

 Gibson than Fort Monroe. Fort Jesup cannot be fairly com- 

 pared, by way of contrast, with a position in the same latitude 

 on the Atlantic, as the warm atmospheric currents from the 

 Gulf of Mexico exercise there a very appreciable influence. 



The laws developed, as respects the mean annual range of 

 the thermometer, are also here corroborated. Washington 

 City has a mean annual range of 84°, while that of Jefferson 

 Barracks is 89' ; the ratio of Fort Monroe, on the one hand, 

 is 73°, and that of Fort Gibson, on the other, is 89° ; and 

 lastly, the range at Fort Johnston is 62°, while that of 

 Augusta Arsenal is 73°. 



It is thus seen that the climate of the region of the great 

 lakes on our northern frontier is not morp contrasted in the 

 opposite seasons than that of Philadelphia — an inference 

 lono; since deduced, from the fact that similar vegetable 

 productions are found in each, while the same plants will not 

 flourish in the interior of New York, Vermont, and New 

 Hampshire. The region of Pennsylvania, as though it were 

 the battle-ground on which Boreas and Auster struggle for 

 mastery, experiences, indeed, the extremes of heat and cold. 

 But proceeding south along the Atlantic plain, climate soon 



