MEASURES OF MENTAL CAPACITY, 



75 



nostril to the occipital condyle, remains stationary. While the upper 

 jaw maintains its fixed position, the lower jaw plays upon it ; and so, 

 while the base-line of the face in the upper jaw remains steadfast, the 

 lines based and dependent upon it— the front facial line above, and the 

 axial line below — are each efiecting variations of 90° in relation to it, 

 the one in relation to its anterior extremity and upper surface, and 

 the other in relation to its posterior extremity and under surface, pass- 

 ing on the way through the angles represented in a b, Fig. 1, and 

 ending as represented in a b, Fig. 2— the two variations together con- 



FiG. 2. 



Fig. 1. 



Degrees of the Superiob and Inferior Facial Angles. 



stituting the variation of 180°, or the half-orbit before mentioned. 

 The base-line of the skull, so far from " varying irregularly," varies 

 not at all, but is always straight, and in the most natural position of 

 the head is always horizontal, while the frontal line of the face and the 

 dorsal line of the body diverge more and more from the horizontal, 

 and become more and more irregular in figure. The position of the 

 head natural to social intercourse and to an outlook upon the horizon, 

 as the general rule, is the one thing in which not only all men, but all 

 vertebrate animals, are agreed, but they take infinite liberty to disagree 

 in all other things, for the sake of showing the infinite diversity of 

 individualities necessary to their harmonious interrelations and to the 

 perfect individuality of the whole. When a man's " head is level," 

 he is on a plane of equality, as a man and an animal, not only with 

 his fellow-men, but with his fellow-creatures, and in a position to har- 

 monize his difierences with theirs. This horizontal position of the base- 

 line of the face makes it the standard by which to compare the other 

 lines, and by which to estimate the degrees of intelligence and afiec- 

 tion as indicated by the degrees of the angles they make with it. 

 When we consider how irregular in position and contour the spine and 

 the features of the face become in the course of transition from the 



