226 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 11, NO. 10 



recorded dates of the hawthorn event and recorded normal mean tem- 

 peratures. It is shown that when the predicted dates are compared 

 with the recorded dates at the same places the variation of the re- 

 corded from the predicted gives a reliable guide to the relative dif- 

 ference between eastern North America and western Europe as related 

 to the advance of spring by latitude and by the equivalents of latitude 

 and longitude in accordance with the bioclimatic law.)^ 



It has been found that, for the same latitudes and a 4-year average, 

 spring advances 13 degrees farther north in western Europe than in 

 eastern North America or on the average is 44 days earlier in western 

 Europe than in the same latitude in eastern North America. 



In a general comparison of the results of the study as to the rela- 

 tions between the predictions and the actual dates, etc., it is concluded 

 that the significance of the results of this study, based on the pheno- 

 logical facts and evidence represented by the hawthorn event and 

 by the thermal mean, is in showing not only the relations between 

 eastern North America and western Europe, as to the relative ad- 

 vances of spring, but the general range of variations, of the recorded 

 dates and thermal mean equivalents, from the dates, and from the 

 thermal means, predicted from an intercontinental base. These re- 

 sults indicate, as nothing else has heretofore, the amount of regional 

 and local diflference in days to be expected for a spring event between 

 a place in eastern North America and places in western Europe. 

 Indeed, the greatest significance of these results is, that the predicted 

 agree so closely with the actual recorded dates, at such a large num- 

 ber of widely separated stations in western Europe, that we may 

 assume that it is practicable to predict dates for certain seasonal 

 events in any given year or average of years for any place on the 

 eastern continent and to do this from a recorded date of the same 

 or equivalent event at the intercontinental base station at Kanawha 

 Farms, West Virginia, and in many cases as accurately as they are 

 usually observed and recorded. 



The results relating to the prediction of bioclimatic zones repre- 

 sented by the recorded dates and thermal means are of special sig- 

 nificance in indicating the zonal relations between eastern North 

 America and western Europe and in showing that the law may be 

 applied to the preliminary prediction of zones of equal adaptation to 

 certain species and varieties of plants and animals, farm and garden 

 crops, as a guide to the successful introduction of desirable species 



"^ The address was illustrated with maps and tables which, together with a part of 

 the paper, are omitted at the suggestion of the author. 



