96 DISCOVERY 



CH. 



that a change of climate has occurred lies with those 

 who believe in it. 



The origin of the belief in a permanent change of 

 climate is probably to be found in the fact that weather 

 everywhere has a tendency to vary in a cycle of about 

 thirty-five years, referred to long ago by Francis Bacon, 

 and established in detail by Prof. E. Bruckner, of Berne, 

 in our own times. In his essay " Of Vicissitude of 

 Things," Bacon remarks : 



They say it is observed in the Low Countries (I know not in 

 what part) that every five and thirty years the same kind and 

 suit of years and weathers comes about again ; as great frosts, 

 great wet, great droughts, warm winters, summers with little 

 heat, and the like ; and they call it the " Prime." It is a thing 

 I do the rather mention, because, computing backwards, I have 

 found some concurrence. 



Neglecting individual years, it may be stated that for 

 about half this cycle the weather is warmer and drier 

 than the average, and for the other half colder and wetter. 

 Or, expressed in another way, wet and cold periods, or 

 warm and dry periods, occur at intervals of about 

 thirty- five years. It is impossible to predict whether 

 any particular year will be colder or warmer than usual, 

 or whether the rainfall will be above or below the average, 

 but Bruckner's cycle certainly does express a general 

 truth, though not very precisely, when applied to the 

 whole earth. In the seventies of the nineteenth century 

 there was a series of very wet years in the British Isles, 

 culminating in the black year of 1879, memorable to 

 all who were then engaged in agriculture. Much the 

 same phase of the cycle was reached in 1912, and that 

 year proved almost as bad for many British farmers as 

 the ruinous year thirty-three years earlier. 



An interesting instance of the application of this 



