ERROR TO CASES OF NORMAL DISTRIBUTION AND CORRELATION. 113 
shall obtain the figure shown, in fig, 7. I'he figure consists of two similar portions, 
each of which is divided into ten equal parts by nine curves ; each curve touching 
the corresponding half of the base at its extremities, and being symmetrical about 
Fig. 7. 
its central ordinate. The curves may be traced by means of Tables III. and IV. 
(pp. 156-158) ; Table III. gives the ordinates in terms of the abscissa, measured from 
the extremity of the base of the figure ; and Table IV. is a converse table, giving 
the abscissse of the different curves in terms of the ordinate.'" 
* The values in Table IV. were calculated by means of Callet’s tables, in which the quadrant is 
divided centesimally. 
VOL. CXCII.—A. 
Q 
