68 



THE DATE PALM. 



The following table gives the results of such a summation of mean 

 maximum temperatures from a number of points where date palms 

 grow or can be grown: 



TABLE 10. Sum of daily maximum temperatures above 18 C. (64.4 F.) for dale season, 

 May to October, inclusive, at the stations named. 



It is remarkable how nearly alike the sums of the daily maximum 

 temperatures are for Salton and Imperial for 1902 when we consider 

 how different the sums of the daily mean temperatures are, (See Table 9, 

 p. 66). If the records for 1902 are correct at both points it would indi- 

 cate a noteworthy difference in climate, the maxim urns being propor- 

 tionally higher at Imperial than at Salton. These sums of temperatures 

 show that the Deglet Noor date is certain to mature fully at Imperial, 

 in the heart of the irrigated portion of the Salton Basin; this is indi- 

 cated not only by the sum of the daily mean temperatures, but still 

 more clearly by the sums of the daily mean maximum temperatures 

 during the fruiting season. 



It is worthy of note that by this system of calculating the sum of 

 heat is higher at Phoenix than at Biskra, whereas the order was 

 reversed when a summation of the mean daily temperature was made 

 (see Table 9, p. 66). This result leads one to hope that the Deglet 



