LECTURE II. 29 



line^ the absolute measure of wliicli is in comparison always 

 assumed as unity, two perpendicular ordinates are erected, 

 and the space between botb extreme points equally divided by 

 two other ordinates. Other perpendiculars are then drawn 

 through the most prominent points of the frontal and occipital 

 bones, and also through the posterior border of the foramen 

 magnum, so that we have upon the base line, at various dis- 

 tances, seven perpendiculars, by wldch the contour of the 

 curve, described by the median plane on the surface of the 

 skull, can be determined with sufficient exactness to be used for 

 graphic delineation. Less attention is paid by Aeby to the facial 

 portion ; it is determined by three lines wliich are drawn to the • 

 points of the nasal bones, to the upper jaw above the roots of 

 the incisors, and to the posterior border of the bony palate. 

 The development of the skull in breadth and height is repre- 

 sented by three transverse sections perpendicular to the base 

 line. The hindmost of these is placed at equal distances be- 

 tween the external auditory opening and the articulation of 

 the jaw; the central one at the point of greatest constriction 

 behind the orbits, while the anterior one joins the zygomatic 

 processes of the frontal bone, where they join the frontal pro- 

 cesses of the zygoma. All these planes are measured by equi- 

 distant ordinates, like the median plane. All measurements 

 being reduced to the base hue as unity, Aeby obtains compa- 

 rable numbers ; and by multiplying the measurements he eli- 

 minates individual deviations, and reducing them to an average, 

 obtains for each race, for each species, a definite mean number, 

 and also comparable reduced normal skulls, capable of being 

 arranged in series. 



Aeby gives the following resume of his measurements and 

 calculations in the Transactions of the Basle Society of Na- 

 turalists : — " I expected to obtain from the median plane in 

 particular, definite starting-points for the scientific division of 

 human races ; I was therefore not a little surprised to find just 

 the contrary. If a close examination of more than five 

 hundred skulls from all parts of the earth entitles one to ex- 

 press an opinion, then I must say, most decidedly, that the 

 normal skulls of all races essentially agree with one another as 



