68 ALES HRDLIKA 



to make contact with a vertical plane, or with the anthropometric 

 rod at two points, viz., in the sacral region and again between the 

 shoulder blades; the axis of vision is horizontal. The height of 

 the vertex above the surface of the seat is to be measured." 



The directions here given need no alteration. The height of the 

 bench for American adults, whose average stature is superior to that 

 of most other Whites, should not be lower than 45, and may con- 

 veniently be 50 cm. (see under " Instruments "). In taking the 

 measurement special care must be taken in each case that the sacral 

 region be well applied to the vertical. The occiput in this position 

 generally touches the vertical plane. 



MEASUREMENTS OF THE HEAD 



Length. The maximum glabello-, occipital diameter of the vault. 



Instrument : The spreading compass or calipers (compas d'epaisseur, 

 Broca or HrdliSka). 



Landmarks: Anteriorly the most prominent point of the glabella; 

 posteriorly the most prominent point on the occiput as shown by 

 the maximum determinable spread of the branches of the compass 

 (Intern. Agr.). 



Method: According to older methods (see Bertillon, Martin), the 

 end part of each branch of the instrument was held in one hand, as in 

 measuring the face. For measurements of the head this is somewhat 

 clumsy. A better method is to hold the compass so that its butt 

 (or joint) rests on the hypothenar eminence of the hand, the two 

 proximal parts of the branches reposing respectively on the ball of 

 the medius and on the second joint of the forefinger, while the thumb 

 holds the instrument to the hand. The observer applies the thumb 

 and middle finger of his left hand, in contact, to just below the glabella, 

 places the free end of the left branch of the compass on these 

 fingers so that the point touches the glabella, and applies the left 

 forefinger over the end. This gives a ball-and-socket arrangement 

 which enables the measurer to hold the point of the left branch of 

 his compass steadily over the glabella without fear of displacement. 

 This branch of the instrument needs no further attention. The right 

 hand is now moved partly around the proximal part of the compass, 

 so that the two branches rest on the ball of the fourth and on the 

 second joint of the middle finger, and are held and controlled by the 

 ball of the thumb and the ball of the forefinger. This hold permits 

 not only an easy handling of the instrument with perfect control, 



