Bird-Life in Southern Illinois 5 



The normal or average mean temperature of the different months at 

 Olney*, as shown by the records for twenty-two consecutive years, are as fol- 

 lows: January, 32.68°; February, 32.93°; March, 44.91°; April, 55.58°; May, 

 66.58°; June, 76.02+°; July, 78.85+°; August, 77.67+°; September, 70.83°; 

 October, 57.62°; November, 44.68°; December, 35.22°. The average mean 

 annual temperature for the same period is 56.18° (extremes being 53.85° and 

 58.48°). The average date of the first killing frost in autumn is October 2 if. 

 The average annual precipitation for the same period is 39.39 inches, but 

 varies from 29.33 inches (in 1891) to 52.91 inches (in 1907), the monthly aver- 

 ages being as follows: January, 2.96+ inches; February, 2.98+; March, 4.33+; 

 April, 3.86; May, 3.69+; June, 3.73; July, 3.53+; August, 2.67+; September, 



A BIT OF LARCHMOUND 



3.41; October, 2.36; November, 3.18+; December, 2.67+. The distribution is 

 not, however, so uniform as might appear from these averages, being, in fact, 

 extremely irregular; that is to say, scarcely two years are closely similar in 

 distribution of the rain- and snow-fall, and any one of the twelve months may 

 represent either the maximum or minimum monthly precipitation for the year. 

 Thus, in the twenty-two-year period the maximum monthly precipitation for 

 a given year has fallen in every month except August and November, these 

 monthly maximums (for the year) ranging from 3.98 inches in (January, 1899) 

 to 12.33 inches (in September, 191 1), the greatest amount recorded for each 



*The latitude of Olney is 38°43'53"; longitude, 88°o3'39"; altitude, 486.3 feet above 

 mean tide at Sandy Hook. 



fThe records are very incomplete as to the last killing frost in spring, the date having 

 been recorded for four years only. The average for these four years is April 24, the extremes 

 being April i and May 10. 



