287 



tion of the live years, adoptiiij;- 5^ C. as the h)\ver limit of useful 

 temperatures, with the following results : 



Sums of mean daUy temperatures, less 5° C. and rejecting neoalivc remainder.^, 

 from December 1 up to the dates of fioicering and of harvest inf/. 



The differences between the numbers for flowering and harvesting 

 show, as in previous years, that although winter wheat requires more 

 heat (716° C.) to bring it up to the flowering point than does rye 

 (515° C), yet after having attained that point the wheat requires 

 less heat (547° C.) than does the rye (581° C.) in order to ripen the 

 grain to the harvest. This fact, wdiich has shown itself in each of 

 the six years, can be considered as well established. 



The harvest of spring harley. — The dates of harvest are, as before, 

 reduced to sea level by allowing for retardation at the rate of four 

 days per 100 meters. The sums of mean daily temperatures, less 

 5° C., counting from the 21st of Maich, wdiich is the mean date of 

 sowing, and up to the date of harvest, are given for each year in the 

 following table : 



The general mean for these six years is (within the range of 

 its probable error) the same as the corresponding figures for 

 winter rye. 



In a fourth memoir, Angot (1890) gives similar computations 

 for the harvests of 1886 and 1887 in France, the number of stations 

 being now appreciably larger than in the preceding years. A new 

 computation of the retardation due to altitude gives him 8.7 days 

 per 100 meters for the lilac, 4.0 for the chestnut, 3.7 for the elder, 



