NORMAL VARIABILITY 



89 



excess of mediocre individuals comes much more 

 prominently into view as soon as a larger number of 

 measurements can be considered, and the results 

 arranged in a different way. 



per cent. 40 >- 



20 



10 



20 40 



FIG. 4. 



~T 



60 



80 100 



The above diagram is constructed from the entries in 

 the third column of the accompanying table, which is 

 taken from Gait on' s * Natural Inheritance.' It repre- 

 sents the variations in the strength of pull (as exerted 

 by an archer in drawing a bow) shown by 519 men 

 as recorded at the International Health Exhibition in 

 1884. Here equal distances measured off along the 

 base line represent equal increments in the strength 

 of pull of the right hand, and the vertical heights of the 

 rectangles erected upon these bases represent the 

 percentage numbers of the men examined which 

 exhibited each value of the character under con- 

 sideration. In this example it is easy to see that the 

 central class is the largest, whilst the extreme classes 

 contain a comparatively small number of individuals. 



