300 OviT Climatic Vicissitudes. [June, 



saturated, and no prevailing wind breaks the column of ascending 

 air. 



Mr. Espy has strongly urged the adoption of his plan for producing 

 rains ; and we think he has formerly petitioned the Legislature of Penn- 

 sylvania for a grant to furnish means to test his theory. But we have 

 never heard of its being granted ; and as there are so many contingen- 

 cies, and the expense of fuel would be so great, we can not think his 

 plan will be of much practical advantage. 



The great currents of air, alluded to in a former part of this article, 

 not only determine the amount of rain we shall obtain, but they modify, 

 very materially, our temperature. The deflected trade-wind from the 

 south-west assists the sun to give us tropical summers. Thus, the average 

 summer temperature of this region is 73 degrees, while Spain, the laud 

 of the orange and vine, is only 70. 'Tis the cold northern and western 

 current of our winters, which brings our yearly average so much lower 

 than theirs, and which destroys the tropical trees that our summers 

 would foster. 



The fluctuations of temperature in this region, as shown in a former 

 article, are, during the winter months, remarkably great ; and the tem- 

 peratures of the same month in different years, is anything but uniform. 

 Sometimes, as last winter, we have the cold and dryness of an extreme 

 northern region, while other winters are open and rainy. So with the 

 spring and summer. The trees are sometimes clad in leafy green early 

 in April ; the next year, perhaps, their vernation is deferred until May. 



Our springs are wonderfully fluctuating in their average temperature, 

 and in that of consecutive days. One day the light vestments of sum- 

 mer scarcely enable us to endure its warmth ; the next, the thick dress 

 of winter hardly keeps out the cold. 



But, notwithstanding this uncertainty in the weather, it is wonderful 

 to note how near the same degree the yearli/ average comes out. Ob- 

 servations taken in this neighborhood, commencing with the year 1814 

 and continued without interruption to 1849, have been kindly laid 

 before us. From them we learn that no year of those thirty-five was 

 above fifty-five degrees, or below fifty, of average temperature, except 

 the solitary instance of 1831. Thirteen of those years, viz.; 1814, 

 '20, '23, '24, '27, '33, '34, '40, '41, '42, '45, '47, '48, had a tempera- 

 ture of fifty-tbree degrees. Six, viz. : 1817, '19, '25, '26, '30, and '44, 

 a temperature of fifty-four. Three of them, viz. : 1828, '39 and '46, a 

 temperature of fifty-five. Three, viz. : 1815, '16 and '32, a temperature 

 of fifty-two. Three, viz.: 1818, '29 and '37, a temperature of fifty- 

 one; and five, viz. : 1822, '35, '36, '38 and '43, a temperature of fifty; 



