CONTENTS. 



ERRATA. 



Page IN, bottom. Denominator of last term in equation for 

 // should rend 



Pa^e 23, 9th line. iH-nominator of last term in equation 1W 

 f/o sliould read 



/'(MI + I)l\m 9 + 1). 



?th line from bottom. Denominator of last term in 

 equation for // should read 



\ m -f 1). 



Method of loaded ordinates 12 



Method of rectangles 13 



Certain constants of the Frequency Polygon 13 



The mean 13 



The mode 14 



The median magnitude 14 



The probable error of the mean 14 



The index of variability 15 



The probable error of the standard deviation .. 15 



Average deviation and probable error 15 



Coefficient of variability 15 



31217 



