538 E. HUNTINGTON SOLAR HYPOTHESIS OF CLIMATIC CHANGES 



and of the time of Christ is a tenth as great as the difference between the 

 climate of today and that which prevailed at the culmination of the last 

 Glacial epoch, the change in. two thousand years has been of large dimen- 

 sions. Yet this would require a rise of only half a degree centigrade in 

 the mean temperature of Palestine. Manifestly, so slight a change would 

 scarcely be detectable in the vegetation. 



Examples of large variations in rainfall accompanied hy slight varia- 

 tions in temperature. — The slightness of changes in mean temperature 

 as compared with changes in rainfall may be judged from a comparison 

 of wet and dry years in various regions. For example, at Berlin be- 

 tween 1866 and 1905 the ten most rainy years had an average precipita- 

 tion of 670 mm. and a mean temperature of 9.15° C. On the other hand, 

 the ten years of least rainfall had an average of 483 mm. and a mean 

 temperature of 9.35°. In other words, a difference of 137 mm., or 39 per 

 cent, in rainfall was accompanied by a difference of only 0.2° C. in tem- 

 perature. Such contrasts between the variability of mean rainfall and 

 mean temperature are observable not only when individual years are se- 

 lected, but when much longer periods are taken. For instance, in the 

 western Gulf region of the United States the two inland stations of Yicks- 

 burg, Mississippi, and Shreveport, Louisiana, and the two maritime sta- 

 tions of 'New Orleans, Louisiana, and Galveston, Texas, lie at the margins 

 of an area about 400 miles long. During the ten years from 1875 to 1884 

 their rainfall averaged 59.4 inches,^* while during the ten years from 

 1890 to 1899 it averaged only 42.4 inches. Even in a region so well 

 watered as the Gulf States, such a change — 40 per cent more in the first 

 period than in the second — is important, and in drier regions it would 

 have a great effect on habitability. Yet in spite of the magnitude of the 

 change the mean temperature was not appreciably different, the average 

 for the four stations being 67,36° F. during the more rainy decade and 

 66.94° F. during the less rainy decade — a difference of only 0.42° F. It is 

 worth noticing that in this case the wetter period was also the warmer, 

 whereas in Berlin it was the cooler. This is probably because a large 

 part of the moisture of the Gulf States is brought by winds having a 

 southerly component. Similar relationships are apparent in other places. 

 We select Jerusalem because we are now discussing Palestine. At the 

 time of writing, the data available in the Quarterly Journal of the Pales- 

 tine Exploration Fund cover the years from 1882-1899 and 1903-1909. 

 Among these 25 years the 13 which had most rain had an average of 34.1 

 inches and a temperature of 62.04° F. The 12 with least rain had 24.4 



?* See A. .7. Henry : Secular variation of precipitation in the United States. Bull. Am. 

 Geog. Soc, vol. 46, 1914, pp. 192-201. 



