196 G. A. Shufeldt on the Subterranean Sources of Lakes. 
no great valley or depression, such as the basins of Paris or 
London. The water ie a head of nearly one hundred and 
twenty-five feet above the level of the lake; is much colder than 
the mean temperature of the location of the wells, being now 
57 degrees Fahrenheit; these facts tending to show that it must 
come from a more elevated region of country, and also froma 
higher latitude. There are two other facts corroborative of 
this point. When the water was first struck the temperature 
was 59 degrees Fahrenheit; it has fallen now two degrees, or to 
57. Then, the first analysis of the water exhibited 72 grains to 
the wine gallon of mineral matter held in solution; the second 
analysis, made only one year afterwards, showed only 56 grains 
of the same matter. These facts, taken in connection with the 
great head of the water, seem to establish exclusively that it 
to prove that prior to the time when the drills penetrat 
the stream, the water had dissolved and absorbed a large qual- 
That the outlet of this stream into Lake Michigan was closed 
b a the earth’s crust, is a probable conclu- 
i i un 
seven or eight feet above the level of the surrounding prairie; 
but geologically or stratigraphically, it is nearly one hund 
and fifty feet above the common devel of Chicago, that is, at 
about one mile distant eastward and into the city. We bore 
