OSTEOMETRY; THE MEASUREMENT OF THE BONES 53 



30. Height of the body of the mandible (tentative) ; similar to the last, 

 but taken in the vertical plane passing between the first and second molars 

 SC. 



31. Maximum thickness of the body of the mandible (tentative); taken 

 in the plane used in the last measurement, between the first and second 

 molars. SC. 



32. Mandibular angle; this is the only angle included in the pre- 

 scription of 1906, and records the inclination of the ramus to the plane 

 of the body, i.e., that of the table upon which the jaw rests when set 

 upon its lower border. For this, a special instrument is required, which 

 consists essentially of two boards, hinged together, and with a device 

 for measuring the angle between them in all positions. The mandible 

 is placed upon one of these, and the other shut down until it is tangent 

 to the posterior border of the ramus. 



Aside from the above measurement of the skull the committee also proposed 

 some nineteen measurements of the head and face in the living subject. These will 

 be found under their proper head (pp. 151-152). 



LATER MODIFICATIONS AND ADDITIONS 



This Agreement of 1906, with its prescribed measurements, has now 

 been generally adopted, and forms the foundation of modern craniometry . 

 A few of the original numbers have been discontinued; several have been 

 modified; and a number of new ones added, the tabulation of which, 

 added here, will bring the list of customary cranial measurements up 

 to the present usage. There is, of course, no reason why an investigator 

 should not make use of any selection or combination from this list 

 which may suit his purpose, or why, if he has any special relation to 

 show, he should not devise whatever new measurements he please, but 

 in this latter case he must take care to define his new measurements with 

 complete accuracy, so that others may follow him with precision. 



I. Measurements discontinued. 



No. 20. Orbito-alveolar height (on side of face.) . 



No. 30. Height of the body of the mandible (on side of jaw). 



No. 31. Maximum thickness of the body of the mandible (taken 



at the plane used in No. 30) . 



The last is still made use of occasionally. The two others were among 

 those marked as tentative in the original prescription. 



II. Measurements slightly modified in later practice. 



No. 2. Glabella-inion length. This measure is now usually 

 replaced by the nasion-inion, No. 33 below. This is 

 also the case in the measurements based upon the dia- 

 graph tracing of the sagittal contour of the skull (cf . pp. 46, 

 58), where the perpendiculars used for the calvarial height, 

 the bregma-position, etc., are erected upon the nasion- 

 inion, and not the glabella-inion, as formerly. 



