Article 1Y .—List of Altitudes in the State of Illinois. 

 By C. W. Rolfe. 



PREFACE. 



Most of tlie elevations in the following list were col- 

 lected during the years 1889 and 1890, as the basis of 

 a model of the State. The others were gathered during 

 the progress of a barometric survey of the State, made 

 under the auspices of the Illinois Board of World's Fair 

 Commissioners. The data were derived as follows: 



From the Mississippi River Commission were obtained a 

 line of levels from Cairo to Dunleith, a line of levels from 

 Fulton to Chicago along the hue of the Chicago, Milwaulcee, 

 and St. Paul R. R., a series of charts of the Illinois shore 

 of the Mississippi, and the low water slope of the Missis- 

 sippi; from the U. S. Lake Survey, a series of geodetic 

 stations between Chicago and Olney; from the Illinois 

 and Michigan Canal, low water levels of the Illinois River; 

 from the U. S. Geological Survey, a series of charts cov- 

 ering a belt of countrj- about fourteen miles wide, be- 

 tween Chicago and Peoria; from the U. S. Coast and 

 Geodetic Survey, a line of levels from Olney to St. Louis, 

 one from Centralia to Cairo, and low water levels of the 

 Ohio and Wabash rivers; from the U. S. Engineers, the 

 preliminary survey of the Hennepin Canal; and from va- 

 rious railway companies, profiles of their lines. 



In order to test and correct the railroad profiles, the 

 bench-mai'ks of the hues of levels and the geodetic points 

 were connected with the nearest railroad stations, the 

 results being used to correct the profiles of these roads ; 

 the elevations of the various railroad bridges over the 

 Illinois and Mississippi rivers above low water, and hence 

 above sea level, were obtained and the railroad profiles 



