INCREASE OK THE BRAIN IN WEIGHT. 



II 



early suggested itself as a means of determining the 

 weight of the brain among those races which were diffi- 

 cult of direct observation. To determine the capacity 

 of a skull requires much art, despite the apparent 

 simplicity of the procedure. For this determination the 

 cranium is usually filled with either shot, water, or some 

 of the varieties of small round seeds, and the amount of 

 this material which it will hold is subsequently weighed 

 or measured. There are more difficulties connected 

 with the operation than would at first sight appear, but 

 leaving them aside, if a given observer in a uniform way 

 determines the capacity of a series of skulls, the figures 

 which he obtains will be fairly comparable among them- 

 selves. For example, the table which is given below is 

 based upon observations by Barnard Davis, in which, by 

 a uniform method, the capacity of a large number of 

 skulls was taken, and then by a formula the brain-weight 

 deduced from the cranial capacity. 1 



TABLE 22. BRAIN-WEIGHTS OF DIFFERENT RACES AS CALCU- 

 LATED FROM THEIR CRANIAL CAPACITIES. (Davis.} 



These figures are given for both sexes and are 

 divided into six geographical groups. The groups are 

 1 Davis, Journ. of A cad. Nat. Science, Philadelphia, 1869. 



