150 F. Waldo — Bruckner's Klimaschwankung 



en. 



2° Fahrenheit. For Central Europe this would mean a dis- 

 placement of isotherms by a distance of 3° latitude, or about 

 200 miles, during the time of oscillation ; and this is no incon- 

 siderable climatic change, for it places the temperature of the 

 lowest period at Riga equal to the coldest at Konigsberg. 



We have next to consider the climatic oscillations as shown 

 for northern Euro-Asia by the duration of time when the 

 waters (rivers) are free from ice, and the dates of their becom- 

 ing free from ice in the spring ; the "secular oscillations of the 

 dates of the grape harvest for Central Europe, and the cold 

 winters of which we have records. The following table gives 

 the deviations, at the times of maxima and minima, in days, 

 from the average for 1816-80, of the lustra periods of the 

 days free from ice, the averages being smoothed out; the 

 negative sign denoting the colder periods : 



1136-40 -96 1811-15... -8-6 



1766-70 +40 1821-25 + 4'5 



1781-85 -3-6 1836-40 -50 



1791-95... +0-6 1876-80 +30 



These data refer to the average of the observations in Euro- 

 Asia and for a short period for the Hudson River. 



Bruckner gives the corrections in days to reduce the dates 

 of breaking up of the ice to the average for 1816-1880 for the 

 separate regions, but does not seem to have been able to unite 

 them in an average. Rykatschew's great memoir on the open- 

 ing and closing of the rivers of Russia and Siberia serves as 

 the chief basis of this research on the ice conditions. On the 

 average the difference in the number of days free from ice 

 between the cold periods and the warm periods amounted to 

 about 16 days for Siberia, 18 days for Central Russia, 25 to 32 

 days for W. and S. W. Russia respectively, and 24 days for the 

 Hudson River. The dates for breaking up of winter ice 

 varied about half these amounts for these Euro-Asiatic regions. 



The record of the dates of the time of the grape harvest in 

 France, South Germany and Switzerland extends back for 

 several hundred years, and the material has been used to deter- 

 mine the forwardness and backwardness of the seasons which 

 are to a certain extent representative of the character of the 

 year. The data used by Bruckner extend back to the year 

 1496. There are regular oscillations from early to late har- 

 vests and these periods obtained from smoothed out data are 

 given in the following table : 



arly harvest. 



Late harvest. 



Early harvest. 



Late harvest. 



1501-05 



1511-15 



1681-85 



1696-1700 



1521-25 



1546-50 



1725-30 



1741-45 



1555-50 



1566-70 



1756-60 



1766-70 



1586-90 



1591-95 



1781-85 



1816-20 



1601-05 



1626-30 



1826-30 



1851-55 



1636-40 



1646-50 



1866-70 



1886-88 



1656-60 



1671-75 







