216 ENVIRONMENTAL CONDITIONS. 



(B) SUMMATIONS OF DIRECT INDICES OF TEMPERATURE EFFICIENCY FOR 



PERIOD OF AVERAGE FROSTLESS SEASON. 



As has been said, direct indices of temperature efficiency offer little 

 promise for our present purpose. We therefore present here only the 

 numerical values (in the third column of table 6, summations above 

 0° F.) and do not reproduce the climatic chart based upon these values. 

 This chart shows practically the same climatic zonation as is shown by 

 Merriam's chart (our plate 37) and by our charts based on the remain- 

 der indices, the numerical values given to the various isoclimatic lines 

 being of course different in each case. 



(C) SUMMATIONS OF REMAINDER INDICES OF TEMPERATURE EFFICIENCY 

 FOR PERIOD OF AVERAGE FROSTLESS SEASON. (TABLE 6, PLATE 38.) 



Remainder indices of temperature efficiency have been derived in the 

 present study by the use of three different values for the constant 

 difference, 32, 39 and 50. It will be remembered that the efficiency 

 index is here taken to be equal to the corresponding temperature index 

 minus the constant difference. Thus we have subtracted 32, 39, or 50, 

 as the case might be, from each of the daily normal means given in 

 Bulletin R, for the period of the average frostless season, and have then 

 summed the daily normal mean efficiency indices thus obtained for 

 each station considered. Columns 4, 5, and 6 of table 6 present the 

 results of these three kinds of summations, above 32°, above 39°, and 

 above 50° F. The method here followed is the same as that employed 

 by Livingston and Livingston, in their summations above 39° F., and 

 our final results for that series of summations are the same as those 

 presented on their chart of ''direct summations," figure 1 in the paper 

 already cited. Our summations above 32° F. are derived by the method 

 actually employed by Merriam, but his failure to publish the data 

 used in making his chart (our plate 37) make detailed comparison 

 impossible. 



