14 



BOTANY OF LA SAL,LE COUNTY. 



Monthly temperature for the years as given from 

 the observations made by Dr. J. O. Harris, for 

 U. S. Weather Bureau, at Ottawa: 



A careful examination of the above table will give 

 one a better idea of temperature prevailing- at Otta- 

 wa than would many pag-es of description. It will be 

 seen that the mean annual temperature does not vary 

 much, but that the components from which it is 

 derived differ considerably from year to year. 



Warmest and coldest day of several years, and date 

 of first and last frost: 



1882: Coldest day, Dec. 7, -13; warmest, June 30, 

 76 deg-. at sunrise. Last frost, May 2, 30 deg-. 



1883: Coldest, Jan, 23, -22; warmest, Aug-. 19, 70 

 degf. at sunrise, 88 deg-. at 2: P. M., 99 deg-. at 3:40 

 p. M. Last frost, April 29, 30 deg-.; first frost, Sept. 

 9, 35 de<?. 



1884: Coldest day, Jan. 5, -30. 



1885: Coldest day, Jan. 28, -24. 



1890: Coldest day, Jan. 22, -6. 



The above data are from the observations of Rev. 

 J. P. Heister, of Farm Ridg-e. Temperature at sun- 

 rise. 



