THE WEATHER CYCLE 55 



1766-75, 1806-20, 1836-55. Taking the cold 

 periods, Bruckner finds that from the years 

 1 020 to n go the oscillation period was 34 years ; 

 from 1 190 to 1370 it was 36 years ; from 137010 

 1545 it was 35 years ; 1545 to 1715 it was 34 

 years, and from 1715 to 1890 it was 35 years. 

 The date at which the rivers of Northern 

 Russia and Siberia are opened to trade by 

 the melting of the ice in the spring, becomes 

 on the whole, alternately earlier and later, and 

 the length of this oscillation is consistent with 

 the rest. The snouts of the Alpine glaciers 

 advance down their valleys and then recede and 

 advance again ; and though owing to the local 

 variation in snowfall all the glaciers do not 

 act simultaneously, the movement, as a whole, 

 is also in a 3435 years cycle. The beginning 

 of the grape harvest in France, southern 

 Germany and Switzerland is celebrated as one 

 of the chief national festivals of the year. The 

 harvest is ripe earlier when the summer is 

 warm and dry, than when the season is cold 

 and wet. And the dates of the first day of 

 harvest are known far back into the Middle 

 Ages. These dates show an advance and 

 retreat in an oscillation of the same length as 

 the other weather variations. The price of 

 grain is a good index to the nature of the 

 seasons ; and Bruckner claims that the price, 

 looked at broadly, shows the same vicissitudes 

 as the various meteorological factors, which 

 control it. 



