1104 



times. Tliis fias been remarked before (These Proceedings, 1905, p. 

 193) and it is confirmed by the fuller material; it is in agreement 

 with Jul. v. Hann's conclusion in his "Lehrbuch dor Meteorologie" 

 1915, p. 115, where it is stated that there is no evidence of "fort- 

 schreitende Aenderungen der Jahrestemperatnr in hisfoiischer Zeit." 

 (no progressive change of annual temperature in historical times). 



On the othei' hand I am of opinion thai another conclusion of 

 V, Hann : "das die Ergebnisse zu Vorausbestimmungen der Wilterung 

 vorlaufig keine Grundiagen abgeben" (p. 647) (that the results offer 

 no base for weather-predictions as yet) no longer strictly holds. 



Let us examine the following table containing only the cold 

 winters since 760, assembled in intervals of 22\/^ years. The two 

 rows at the bottom give respecti\'ely the averages for the six last 

 89-year periods and for all 13 periods (the differences are nnim- 

 portant). The figures in brackets represent the very cold oi- hard 

 winters (coeff. 4 or 5). 



TABLE V. 



Frequency of severe (resp. very hard) winters 



760—1916, in 22-year periods. 



Period 



P. year 

 1 - 22 



P. year 

 23-45 



P. year 

 45 67 



P. year 

 68 89 



