INTRODUCTION. 



I. Physical features of the State. 



Qeueral. The total length of the State of Dlinois is 878 miles, 

 the extremes of latitude being 36" 59' and 42° 30', while the maxi- 

 mum breadth is 210 miles. The great length of the State from 

 north to south gives it a climatic range of 5j degrees, which exceeds 

 that of any other State except California. The topography of Illi- 

 nois is so simple, however, that any decided differences of climate 

 or temperature must necessarily result from difference of latitude 

 or season, there being no mountains sufficiently elevated to produce 

 any perceptible modification in this respect. 



"Illinois occupies the lower part of that inclined plane of which 

 Lake Michigan and both its shores are the higher sections. Down 

 this plane in a very nearly S. W. direction the principal rivers 

 have their courses to the Mississippi. The lowest section of this 

 plane is also the extreme S. angle of the State, and is only 340 ft. 

 above the Gulf of Mexico. The greatest elevation of the country 

 is 1,150 ft., and the mean elevation about 550 ft., above tide water. 

 Next to Louisiana and Delaware, indeed, Illinois is the most level 

 State of the Union. A small tract in the N. W. corner of the 

 State around Galena is hUly and somewhat broken, and there are 

 bluffs on the Mississipi and Illinois rivers ; but by far the greater 

 portion of the surface consists of vast level or gently undulating 

 prairies. A low mountain ridge extends across the S. end of the 

 State, from Grand Tower, on the Mississippi to Shawneetown on 

 the Ohio, constituting the fruit region of southern Illinois." (Ameri- 

 can Cyclopedia.) 



The highest point within the State is said to be near the north- 

 em border, between Freeport and Galena, where the so-called "mounds" 

 are 1,100 to 1,150 feet above sea-level, though only 200 to 250 feet 

 above the surrounding country. The lowest part of the State is, 

 of course, the river-bed at Cairo, where the elevation above mean 

 tide in the Gulf of Mexico is 840 feet. The general surface in the 

 southern is much more varied or broken than that of the central 



