110 



INTRODUCTION. 



Climate. In a territory so extensive as that em- 

 braced -witliin the United States, there is ample oppor- 

 tunity to test the eflfect of climate ; and the topograph- 

 ical character of the country aids in defining the 

 bounds of this influence, and in enabling us the more 

 readily to appreciate its amount. It may be said, in 

 general, that the country presents a great diversity of 

 climate, varying from that of the northern district, 

 Avhere frost and snow prevail nearly six months in the 

 year, and the alternations of temperatui-e are rapid and 

 excessive, the extreme range of the thermometer ex- 

 ceeding 130° of Fahrenlieit, to that of peninsular Florida, 

 ■where the seasons blend imperceptibly with each other, 

 vegetation is never dormant, and flowers succeed each 

 other without interval. 



The mean summer and Avinter temperature of the two 

 most northern and the two most southern military posts, 

 the last of these being an insular one, together with that 

 of the most south-western post, taken from Dr. Ferry's 

 w^ork, Avill illustrate the subject, and show that we have 

 ■within our limits a range of climate as excessive in its 

 extremes as those of Moscow and of Cairo. 



