The Chicago Academy of Sciences. 43 



ment to organize the parent society, "The Chicago 

 Academy of Natural Sciences," 1856, to the date of the 

 destruction of the Academy's property in the great fire, 

 1871. The second period dates from the fire, and closes 

 with the opening of the Matthew Laflin Memorial build- 

 ing, in 1894. 



In the later days of the second period (1892) 

 the Academy inaugurated one of the most important 

 branches of its work. This, the u Natural History Sur- 

 vey of Chicago and Vicinity," is of value both to the 

 student of natural history and to the business man, for, 

 when completed, it will have finished an investigation 

 of both economic and purely scientific features of the 

 area covered. 



. At the time of organization of the survey three 

 general departments were decided upon: Geology and 

 allied sciences, topography, zoology and botany. It 

 was further decided that the work in the several divis- 

 ions of these departments should be intrusted to men 

 recognized as specialists, and published as bulletins 

 and reports, which should be as nearly monographic as 

 possible. Since the organization of the survey the 

 work has been steadily progressing, and a large amount 

 of data has been collected. 



The area covered by the survey was known to be 

 peculiar in two distinct systems of drainage, either of 

 which might, under certain conditions, prevail over the 

 other. As this peculiarity of the drainage is of great 

 scientific interest, it was thought desirable to emphasize 

 this by fixing upon the following boundaries: Begin- 

 ning at the north line of Cook county and Lake Mich- 

 igan, thence westward, coincident with the north line 

 of Cook county to Kane county ; thence southward 

 along the east line of Kane and Kendall counties to the 

 southeast corner of Kendall county; thence eastward, 

 coincident with the south line of Cook county to the 

 east line of Lake county, Ind.; thence northward to 

 Lake Michigan. 



