116 ROBERT BENNETT BEAN 



birth were obtained in all except a few instances and the child 

 reckoned to be a certain age if it is aiiywhere within six months 

 of that age. For instance, if a child was born in January 1902 

 and the records were made in July 1908, the child was recorded 

 as six years old, but if the records were made in July 1907 the 

 child was recorded as five years old, and if the records were made 

 in August, 1908, the child was recorded as seven years old. This 

 method is practically the same as obtaining from the child th^ 

 nearest birthday, although in giving that the child is apt to 

 miscalculate. 



The stature was obtained by using a stationary vertical gradu- 

 ated scale with sliding arm to come down on the child's head. 

 This was pressed firmly and several readings were made for each 

 record, the child standing erect with its back against the scale. 

 The children were measured without shoes when feasible, other- 

 wise allowance was made for the height of the shoe heel. The 

 average or 'mean' stature is used although the 'median' and the 

 'mode' will be presented. 



Many other measurements were made, including sitting stature, 

 weight, head and face dimensions, with observations of the hair 

 and eyes, but these are reserved for future publication. The 

 teeth were examined for eruption, decay, absence, or irregularity. 

 For detailed observations see the table of records, which shows 

 the condition of eruption and decay of each tooth in each indi- 

 vidual, and will be published either separately or on file in The 

 Wistar Institute of Anatomy in Philadelphia. 



The standard deviation, coefficient of correlation, probable 

 error, etc., are not given, because the characteristics of the indi- 

 vidual rather than the mass are desired. However, the average, 

 the mean, the mode, and the extremes have been computed, and 

 these with other factors are utilized in an attempt to determine 

 individual characteristics. 



At the end the morphologic type, the sex, and the race are used 

 to assist in explaining individual differences, such as why one 

 child has a certain tooth erupted 5 years earlier than another 

 child has the same kind of tooth erupted, which occurs with great 

 frequency. 



