SECT. 8.] Arrangement and Formation of the Series. 35 



to an exception. We may presume then that the curves are 

 of the lop-sided character indicated by the accompanying 

 diagram.&quot; The same facts are also ascertained in respect to 

 place variations as distinguished from time variations. To 

 these may be added some statistics of my own, referring to 

 he heights of the barometer taken at the same hour on more 

 than 4000 successive days (v. Nature, Sept. 2, 1887). So far 

 as. these go they show a marked asymmetry of arrangement. 



In fact it appears to me that this want of symmetry 

 ought to be looked for in all cases in which the phenomena 

 under measurement are of a one-sided character; in the 

 sense that they are measured on one side only of a certain 

 ixed point from which their possibility is supposed to start. 

 For not only is it impossible for them to fall below this point : 

 ong before they reach it the influence of its proximity is felt 

 n enhancing the difficulty and importance of the same 

 amount of absolute difference. 



Look at a table of statures, for instance, with a mean 

 value of 69 inches. A diminution of three feet (were this 

 )ossible) is much more influential, counts for much more, 

 m every sense of the term, than an addition of the same 

 amount ; for the former does not double the mean, while the 

 latter more than halves it. Revert to an illustration. If 

 a vast number of petty influencing circumstances of the kind 

 already described were to act upon a swinging pendulum we 

 should expect the deflections in each direction to display 

 symmetry ; but if they were to act upon a spring we should 

 not expect such a result. Any phenomena of which the 

 latter is the more appropriate illustration can hardly be 

 expected to range themselves with symmetry about a mean \ 



1 It must be admitted that ex- shown this asymmetry in respect of 

 perience has not yet (I believe) heights. 



32 



