394 



POPULAR SCIENCE MONTHLY. 



roof of the orbit is low like that of the long skull, but the lower border 

 does not extend so far downward and the direction of the transverse 

 diameter is more oblique. 



Measurements of the direction of the axis of the orbit in these 

 three classes show that in the long skull the direction is usually quite 



Fig. 8. 



Front view of Long Skull : 



Cephalic Index 71.4 : 100. 



Fig. 9. 



FfioNT VIEW OF Tall Skull : 



Cephalic Index 81 : 100. 



Fig. 10. 



Front view of Broad Skull : 



Cephalic Index 85 : 100. 



low, that in the tall skull it is much higher and that, while the axis of 

 the broad skull is lower than that of the tall one, it is scarcely as low on 

 the average as in the case of the long skull; and these comparative 

 positions of the axes of the orbits in the prepared skulls correspond 

 remarkably with the positions of the visual plane in the case of living 

 subjects with heads of corresponding types. That is, the visual plane 

 of the long head is low, of the broad head also low and that of the 

 tall head is high. 



Notwithstanding the apparent simplicity of these relations of the 

 form of the orbit with the type of the skull and of the direction of the 

 visual plane to the type of cranium, there are, in practice, certain modi- 

 fying features. 



The most important of these from the anatomical standpoint is 

 found in the angle of the face. In forming a judgment, therefore, of 

 the probable direction of the normal visual plane in the living subject 

 without resorting to measurements by the tropometer, it is necessary 

 to measure or to estimate this angle. None of the measurements em- 

 ployed for the prepared skull will serve the purpose here, and it has 

 been found most practical to use for fixed points for the measurement 

 of this angle the following: the glabella, which is the elevation above 

 the root of the nose and just between the ridges of bone above the orbits ; 

 the depression just below the nose, and the tip of the chin. 



If these three fixed points are selected for the measurement of 

 the angle of the face, it will readily be seen that this angle varies 

 greatly in different individuals. It may, indeed, vary considerably in 

 heads belonging to the same type. Yet, on the whole, there is a pretty 



