36 
Notes on the History of Corrddtion 
lines and the Hrst correlation table (of stature in parentage and offspring) as we 
should now call it. 
AlsoGalton gives the diagram* which indicates how he discovered observationally 
the form of the normal frequency surface. He proceeded to smooth his correlation 
DIAGRAM BASED ON Table i . 
(ail female heights are mtdtiplied by I 08 ) 
MID-PARENTS ADULT CHILDREN 
1 their Heights , and Deviations from 68+ inches. 
Heights Deviates 64 6,5 66 67 68 69 70 71 72 73 
in in 
inches inches -4 -3 -2 -1 O +1 +2 *3 +4 
table by taking the mean of four adjacent cells, and then drawing contour lines 
through points of the same frequency. He found such contour lines were a system 
of concentric similar and similarly placed ellipsoids and that the regression lines 
Keproduced here by permission of the Royal Authropological Institute. 
