64 Origin, or Process of Causation of the Series. [CHAP. ill. 



fail to detect this regularity. Thus in men; their height, 

 strength, weight, the age to which they live, the diseases of 

 which they die ; all present a well-known uniformity. Life 

 insurance tables offer the most familiar instance of the im 

 portance of these applications of Probability. 



(2) The same peculiarity prevails again in the force 

 and frequency of most natural agencies. Wind and weather 

 are seen to lose their proverbial irregularity when examined 

 on a large scale. Man s work therefore, when operated on 

 by such agencies as these, even though it had been made in 

 different cases absolutely alike to begin with, afterwards 

 shows only a general regularity. I may sow exactly the 

 same amount of seed in my field every year. The yield may 

 one year be moderate, the next year be abundant through 

 favourable weather, and then again in turn be destroyed by 

 hail. But in the long run these irregularities will be equalized 

 in the result of my crops, because they are equalized in the 

 power and frequency of the productive agencies. The 

 business of underwriters, and offices which insure the crops 

 against hail, would fall under this class ; though, as already 

 remarked, there is no very profound distinction between them 

 and the former class. 



The reader must be reminded again that this fixity is 

 only temporary, that is, that even here the series belong to 

 the class of those which possess a fluctuating type. Those 

 indeed who believe in the fixity of natural species will have 

 the best chance of finding a series of the really permanent 

 type amongst them, though even they will admit that some 

 change in the characteristic is attainable in length of time. 

 In the case of the principal natural agencies, it is of course 

 incontestable that the present average is referable to the 

 present geological period only. Our average temperature 

 and average rainfall have in former times been widely 



