CLIMATE. 



CLIMATE. 



Along the Atlantic coast of the United States, 

 Ihe mean temperature of the year diminishes 

 in a very unequal ratio. Between Charleston 

 and Philadelphia, the difference of means is 

 10 Fahr., or in the proportion of about 1 

 of temperature to 1 of latitude. Between 

 Philadelphia and Eastport,Maine, the difference 

 in means is much greater, namely, 12.33 

 Fahr. being in the increased proportion of 

 nearly 2'5 of mean temperature per degree of 

 latitude. Again, between Charleston, S. C., 

 and New York harbour, the difference of means 

 is 12 0< 78, or l-59 per degree of latitude. Be- 

 tween New York harbour and Eastport, Maine, 

 the difference is 11, or about 2f Fahr. per 

 degree of latitude. The average proportion 

 between Charleston, S. C., and Eastport, Maine, 

 is equal to about 2 of temperature for each 

 degree of latitude. 



In approaching south, the extremes of win- 

 ter and summer grow less, and the seasons 

 glide more imperceptibly into each other. At 

 Fort Snelling, situated in the excessive climate 

 of the west, in latitude 44 0< 53, the difference 

 between the summer and winter means is, as 

 has been before stated, no less than 56-60 ; at 

 Eastport, Maine, 39-15, at West Point, N. Y., 

 40-75, at Charleston, S. C., 30-34, at St. Au- 

 gustine, Florida, 20, whilst at Key West, it is 

 only ll-34. 



" There is," says Dr. Forry, little difference 

 between the thermometrical phenomena pre- 

 sented at Key West and the Havana. In the 

 West India islands, the mean annual tempera- 

 ture near the sea is only about 80. At Bar- 

 baiDes, the mean temperature of the seasons 

 is winter, 76, spring 79, summer 81, and 

 autumn 80. The temperature is remarkably 

 uniform ; for the mean annual range of the 

 thermometer, even in the most excessive of the 

 islands, is only 13, and in some it is not more 

 than 4. Contrast this with Hancock Bar- 

 racks, Maine, which gives an average annual 

 range of 118, Fort Snelling, Iowa, 119, and 

 Fort Howard, Wisconsin, 123! 



" The peculiar character of the climate of 

 East Florida, as distinguished from that of our 

 more northern latitudes, consists less in the 

 mean annual temperature than in the manner 

 of its distribution among the seasons. At Fort 

 Snelling, for example, the mean temperature 

 of winter is 15-95, and of summer 72-75, 

 whilst at Fort Brooke, Tampa Bay, the former 

 is 64-76, and the latter 84-25, and at Key 

 West, 70-05, and 81-39. Thus though the 

 winter at Fort Snelling is 54-10 colder than at 

 Key West, yet the mean temperature of sum- 

 mer at the latter is only 8-64 higher. In like 

 manner, although the mean annual tempera- 

 ture of Petite Coquille, Louisiana, is nearly 2 

 lower, that ..f Augusta arsenal, Georgia, nearly 

 8, and that of Fort Gibson, Arkansas, upwards 

 of 10 lower than that of Fort Brooke ; yet at 

 all, the mean summer temperature is higher. 

 Between Fort Snelling on the one hand, and 

 fort Brooke and Key West on the other, the 

 relative distribution of temperature stands 

 thus: Difference between the mean tempera- 

 ture of summer and winter at the former 56-60, 

 and at the two latter 16-49 and ll-34; dif- j 

 fer^nce between the mean temperature of the ' 

 334 



warmest and coldest month, 61-86 Ctaipared 

 with 18 c -66 and 14-66 ; difference between the 

 mean temperature of winter and spring, 30-83 

 to 8-35 and 5-99 ; and the mean difference of 

 successive months, 10-29 to 3-09 and 2-44." 



A comparison in regard to equality and 

 mildness of climate drawn between the sea- 

 sons of Florida and those of the most favoured 

 placs on the European continent, these of 

 Italy and southern France, results generally in 

 favour of the Florida Peninsula. At Key West 

 the annual range of the thermometer is but 37. 

 See table of monthly mean temperatures, under 

 the head of ATMOSPHKHK. 



CLIMATE, CHANGES OF. The question 

 has been much debated, whether the tempera- 

 ture of the crust of the earth or of the incum- 

 bent atmosphere has undergone any perceptible 

 changes since the earliest records, either from, 

 the efforts of man in clearing away forests, 

 draining marshes, cultivating the ground, or 

 other causes. La Place has demonstrated very 

 satisfactorily, that since the days ofHipparchus, 

 an astronomer of the Alexandrian school, who 

 flourished about 2000 years ago, the earth can- 

 not have become a single degree of heat warmer 

 or colder, as otherwise the sidereal day must 

 have become either lengthened or shortened, 

 which is not the case. 



As to the question of changes in atmospheric 

 temperature affecting the seasons, M. Arago 

 thinks that sufficient proofs exist to justify the 

 conclusion that in Europe, at least, a sensible 

 elevation of the annual mean temperature has 

 resulted from the conquests of agriculture. 

 The thermometer is comparatively a modern 

 instrument, invented by Galileo in 1590, but 

 still left so imperfect, that it was not till 1700 

 that Fahrenheit succeeded in improving and 

 rendering it a correct and perfect instrument. 

 It is evident that the want of exact instrumental 

 observations prior to the commencement of 

 agricultural improvements must render it ex- 

 tremely difficult to determine with any preci- 

 sion, what changes may have been effected 

 through these in the mean temperatures of the 

 year or particular seasons. Hence, notwith- 

 standing the expression of his belief in the 

 changes of atmospheric temperature, M. Arago 

 looks to America for the necessary data by 

 which the point must be definitely settled. 



" Ancient France," he remarks, "contrasted 

 with what France now is, presented an incom- 

 parably greater extent of forests ; mountains 

 almost entirely covered with wood, lakes and 

 ponds, and morasses, without number ; rivers 

 without any artificial embankment to prevent 

 their overflow, and immense districts, which 

 the hands of the husbandman had never 

 touched. Accordingly, the clearing away of 

 the vast forests, and the opening of extensive 

 glades in those that remain ; the nearly com- 

 plete removal of all stagnant waters, and the 

 cultivation of extensive plains, which thus are 

 made to resemble the stepes of Asia and Ame- 

 rica these are among the principal modifica- 

 tions to which the fair face of France has been 

 subjected, in an interval of some hundreds of 

 years. But there is another country which is 

 undergoing these same modifications at the 

 present day. They are. there progressing 



