297 



subject to steady and in all probability periodic variations and inter- 

 chano^es, Avhicli aiv difficult to recognize in consequence of the mani- 

 fold combinations of the numerous effective factors. Climatic 

 changes, extending over long periods of time, are indicated by 

 geological periods, which latter themselves demonstrate again only 

 the gradual and not any sudden alterations of climate. Sudden, 

 and even very moderate slow changes of climate cause the destruc- 

 tion of the vital organism. 



The comparison of the climatic conditions of individual years, the 

 differences in the yield of fruits of various kinds, as already men- 

 tioned above, the unfavorable years in central Europe at the end of 

 the sixteenth and eighteenth and beginning of the nineteenth cen- 

 turies, and the very favorable seasons for grain and wine in the last 

 quarter of the seventeenth and at the beginning of the eighteenth 

 century and in the first third of the nineteenth century, together with 

 the recurring failure inider similar conditions of crops, particularly 

 of wine, in 1847 and 1881, caused by the cool weather at the end of 

 summer and beginning of autumn, in spite of the hot summer which 

 had preceded it, etc., and furthermore the exact numerical researches 

 based on results of observations of the meteorological elements, all 

 show a variability of climate such as is accomplished within a century, 

 or even Avithin the lifetime of a man, and which can be most positively 

 recognized from year to year, from decade to decade. To find the 

 causes of these changes belongs to those who have devoted themselves 

 to researches in the laws of meteorolog:y, and particularly to discov- 

 ering the methods by which to prognosticate the conditions of weather 

 for long periods in advance. 



Distribution of good and poor wine crops, hy decades, since 1600. 

 [From Fritz (1889), p. 301.] 



