Public Parks. 51 



of 48 feet, the highest point in any direction within ten miles 

 of Chicago. Continuing to the Des Plaines there is a descent, 

 the bottom of the river being 26 feet ; then there is a marked 

 increase in the ascent, so that at fifteen miles the surface is 102, and 

 at twenty miles 125 feet above the level of the lake.* North-west of 

 the city, at four miles, we only find an elevation of 10 feet ; at seven 

 miles of 27 feet, where we again strike the original lake shore ; at 

 ten miles, 40 feet ; at eleven miles, 65 feet ; at twelve miles, 82 feet ; 

 from this point there is a gradual descent to Des Plaines River, where 

 the elevation is 33 feet ; thence the ascent is gradual and at twenty 

 miles distant it is 96 feet.f It will be seen from the foregoing that the 

 highest point within five miles of the mouth of Chicago River, in any 

 direction, is only 23 feet, and for ten miles, 48 feet above the level of 

 the lake ; and that a large portion of this ground is low and swampy, 

 with but little surface drainage, and an average elevation of about 12 

 feet. As a necessary consequence, as in all plains, great and sudden 

 changes of moisture and temperature take place. The winds, meet- 

 ing with no obstruction, have full sweep ; in fact, the topography of 

 the surroundings of the city tends to this result, favoring even the 

 prevailing winds of this latitude. The only interruption in this open 

 plain to the winds, may be said to be the narrow belt of timber on 

 the Des Plaines, and with here and there an occasional patch of thinly 

 covered wood-land, on the elevations which once were the shores 

 of the lake. With this exception, the open plain may be said to con- 

 tinue for a great distance north-west, west, and south-west. It is true, 

 timber is scattered north and south, but unfortunately not enough to 

 materially influence the climate, in addition to the fact that the 

 winds are rarely from either direction. In an area of 400 square 

 miles surrounding Chicago, there are only about 20 square miles 

 thinly covered with timber ; ten of these are found on the north side 

 of the city, and along the North Branch of Chicago River ; five 

 south and south-east ; and ten on the ridges six miles west, and in 

 tlie valley of Des Plaines River. 



LAKE MICHIGAN. 



Of all the local conditions that obtain at Chicago, none exercise 

 a greater influence on the climate than Lake Michigan. It 

 moderates the extreme cold of winter, and the oppressive heat of 

 summer ; increases the humidity of the atmosphere, and tlie 



• Northwestern R. R. 

 t Galena R. R. 



