146 TRANSACTIONS OF THE ILLINOIS 



this purpose ; and yet there are the remains of dams and mill6 to tell of its use. Why 

 60 great a change ? Is it not that the rank vegetation of the prairies acted in some de- 

 gree as a forest does, for a protection against evaporation ; from its annual decay, a thick 

 coating of humus being formed, which is a powerful absorbent of water ; while it pre- 

 vented by its tough roots, the water from washing the loose soil, and forming torrents ; 

 and thus the water was delivered to the streams more equably ? Now, every heavy 

 shower converts them into foaming torrents, and they rush to the Mississippi, discolored 

 with the earth they bear along, while a few hours of sunshine serves to render them 

 again insignificant brooks. In regard to asserted changes of climate, it does not seem 

 that we have as yet definite observations, sufficient to enable us to decide. Only this we 

 must remember, the thermometer is not the only index. There may be subtle climatic 

 changes which the thermometer can not indicate, as in miasms. May there not be such 

 also in regard to the growth and ripening of certain fruits ? Early settlers in Quincy, 

 Springfield and Urbana assert that till 1854 (I think), they were never troubled at all to 

 raise the peach, but since then, it is uncertain. If this be true, why is it ? Every one 

 has, I presume, noticed the persistency with which, in the heat of summer, showers cling 

 to certain tracts, while they refuse to visit others close at hand. At Quincy, many show- 

 ers follow the course of the Mississippi, or else one of the streams flowing into it, or 

 empty themselves upon the wooded lands. Thus at Springfield, they follow the course 

 of the Sangamon, and sweep around the city. Last summer at Urbana, we had several 

 valuable showers, while at Mr. Dunlap's, four miles distant, there were none, the show- 

 ers clinging so closely to the timber as even sometimes to leave Champaign without a 

 drop of rain, while we had a copious shower. 



But what climactic changes, if any, may we reasonably hope to produce in the course 

 of three years ? 



If the observations made upon the effect produced by felling and by planting trees 

 are correct, we may hope, by results flowing from the efforts of societies like this, to 

 produce at least some. 



These great plains afford an immense evaporating surface to the intense heat of the 

 summer's sun. Cultivation increases that surface, and the tendency to evaporation. 

 This being so, they will always be subject to great electrical changes. Hence the liabil- 

 ity to hail, severe thunder storms and tornadoes. But when these prairies are subdivided 

 into farms of reasonable size, each homestead, with its orchards of fruit trees, with its 

 shade and shelter trees along the roadsides, and by the home, with shelter belts of hedge 

 or of trees subdividing the farm, and thus protecting against the free sweep of the chill 

 Masts of winter, and the drying and denuding winds of spring and summer, we may 

 expect that these electrical conditions will be somewhat modified. Showers will be dis- 

 tributed more equally, and the liability to tornadoes will be diminished. Besides, if the 

 temperature, as manifested by the thermometer, be not changed, will not the apparent 

 temperature be modified ? 



Dr. Kane states that he could go out with the thermometer at 50 deg. below zero, and 

 f^el no great inconvenience. But, if the wind rose, no one could stand it. Over these 

 prairies there is almost always a wind from some direction — generally from the south- 

 west, as the trees lean north-east ; and this makes the cold more unendurable than a 

 much lower temperature in the forest. The Northers of Texas are examples of the 

 same thing. We all know how much warmer it is appareutly under the lee of a forest 

 on a windy day. Will not, then, these cold, chilling blasts be sensibly modified when the 

 country is thus settled, and a system of tree planting is universally adopted ? 



