23 
measurements, and also those of height, are being mde is 
most important, and requires the careful attention of the 
observer. The subject must sit with the body upright and 
the head straight, the line of vision directed horizontally 
forwards to a point a little distance off, placed at the same 
height as the eyes. Having adjusted the head in the proper 
position, the instrument is placed with one limb resting on 
the vertex, while the stem of the instrument is held vertically 
in front of the face (particular attention should be paid to 
the fact that the instrument must be held vertically , as some 
travellers have erred in taking an oblique measurement from 
the back of the head to the chin, which is useless) ; to secure 
the vertical position of the instrument, a small plumb-line 
should be temporarily fixed to the base of the curved part 
of its upper arm or on the end of the carrier, Plate 11 ,^. 
After each measurement is taken the observer should 
see that the subject is in the correct attitude before taking 
the next. 
5. Vertex to Root of Nose. —The point on the root of the 
nose to which this measurement is taken is the same as 
that in measuring the length of the nose, Plate II, c. 
6. Vertex to Mouth. —The lower point is the line of the 
lips when closed, Plate II, d. 
7. Vertex to Chin .—The point on the chin is that corres¬ 
ponding to the under surface of the lower jaw, as shown in 
Plate II. 
8. Vertex to Tragus of Ear , or supra-auricular projection, 
is measured by rotating the instrument to the side of the 
head, the horizontal arm still resting on the vertex. The 
lower arm is projected against the middle of the tragus 
(the small projecting portion of the external ear which 
guards the opening of the meatus, in front), at the point 
where it starts from the side of the face, marked X, Plate II. 
By adding the length and breadth of the head, and the 
height from the tragus to the vertex together, and dividing 
the product by 3, the cephalic module of Schmidt is obtained, 
which enables us to compare approximately the volume of 
different heads. 
