Climate of Middle Illinois. 



13 



and the greatest range in twenty-four hours was observed 1876 in January 

 28th, 2 p. M., to 29th in the morning the mercury fell 53° from 61 to 8, 

 and again 1881 in January 13th to 14th falling from 34 to — 10. Such 

 high daily oscillations are frequent, particularly in February, December 

 and April, and even in July the greatest difference in twenty-four hours 

 was 37° (1860 2d to 3rd.) 



To show the march of the mean temperature from day to day during 

 the year the mean for each day (in thirty years) is computed in table two. 



Table 2. 

 DAILY MEAN TEMPERATURE, 1855 to 1885. 



From the 5th of March the mean keeps above the freezing point, 

 rising by and by with little oscillations to the maximum mean on the 

 16th of July (80.4,) then it falls slowly to the middle of September, and 

 more rapidly to the 29th of November, when it reaches the freezing point, 

 under which it keeps from the 7th of December to the 21st of February, 

 with the only exception on the 12th of December. From the 22d of Feb- 

 ruary to the 5th of March only the 23d and 24th of February and the 4th 

 of March have the mean temperature below freezing point. 



There are small oscillations in spring and fall, the depressions of 

 which may be filled after longer observations, but those in winter are too 



