20 



BIRDS OF ILLINOIS. 



With regard to this subject we cannot, in the present work, enter 

 into detail, but must be content with presenting a few data by way 

 of illustration of the above remarks. 



In the "Tables and Results of the Precipitation, in Eain and Snow 

 in the United States," collected and published (in 1872 and 1881) 

 by the Smithsonian Institution, Professor Charles A. Schott, the 

 compiler, recognizes (pp. 127133 of first edition, 197-203 of second 

 edition), ten geographical areas, each of which is characterized by 

 marked peculiarities in the distribution and quantity of the rainfall. 

 Illinois comes chiefly if not entirely within "Type IV" of these 

 regions, including the Ohio Valley, which is characterized as follows : 

 "One principal maximum, and one principal minimum; the former 

 early in June, the latter early in February. Range, moderate." 

 This region is to be compared, in the illustration of our subject, 

 with "Type I.Atlantic seacoast from Portland to Washington," which 

 has "Three nearly equal maxima, about the middle of May, August 

 and December, and one principal minimum about the beginning of 



February;" "the range between the extreme monthly values 



small," and "the August maximum generally the highest." 



These are, however, mere technical differences, only appreciable 

 to, or recognizable by, the meteorologist. 



With the following data* we shall dismiss this subject: 



I. Comparative mean annual temperature and rainfall. 

 Chicago. L&i. 4152' alt. 660.92 feet. 



Mean annual temperature (8 years) 491. 



Total annual rainfall (8 years( 35.27 inches. 



Boston. Lat. 4221', alt. 142.19 feet. 



Mean annual temperature (9 years) 484. 



Total annual rainfall (9 years) 50.82 inches. 



Indianapolis, Ind.L&i. 3947', alt. 746.58 feet. 



Mean annual temperature (1 year) 533. 



Total annual rainfall (8 years) 45.22 inches. 



Philadelphia, Pa. Lat. 3957, alt. 52.42 feet. 



Mean annual temperature (9 years) 531. 



Total annual rainfall (8 years( 42.93 inches. 



Compiled from the Annual Reports of the Chief Signal Office, U. 8. Army. 1871-1880. 



