56 LABORATORY MANUAL OF ANTHROPOMETRY 



means of the diagraph. Of all craniograms, or tracings thus made, this 

 one, the median sagittal, is by far the most important, and is so emphat- 

 ically the craniogram par excellence, that it is the one always referred to 

 when the word is used without modification, (cf. Fig. 26, p. 46). 



Quite aside from its use in furnishing another method of presenting 

 the more usual lines, and thus corroborating the results of direct measure- 

 ment, there are certain important internal lines, such as the calvarial 

 height line, or the bregma position line, that are obtainable in no other 

 way than by means of this craniogram. Especially , however, in the 

 presentation of various angles, mainly internal ones, lies the chief useful- 

 ness of this figure, where they need merely to be constructed by means 

 of lines drawn between the proper points, and then read off with a 

 transparent protractor. 



The most important data obtainable from such a craniogram may 

 be presented here in three groups; corroborative measurements, linear 

 measurements, and angles. 



1. Corroborative Measurements 



Any linear measurements that may also be taken directly on the 

 skull will serve to test the accuracy of a craniogram, but the longer the 

 line employed, so much greater is the visible error, and the severer the 

 test. Thus the two best measurements for this purpose are the two 

 greatest dimensions of the profile view, the maximum length and the 

 basion-bragma height. In making this test a discrepancy of 1 mm. 

 or so is not a serious one, as it may be accounted for in large part by the 

 varying width of the pencil point, or a slightly oblique position of the 

 median axis of the pencil. Such slight discrepancies should be corrected 

 in the craniogram by erasing and redrawing portions of the curve, yet 

 such corrections should not be attempted if they involve much more 

 than the breadth of the pencil mark. 



In this enumeration, as everywhere throughout this book, measure- 

 ments bear the same numbers as when first mentioned; all measurements 

 taken from the foregoing list, therefore, will here have the former numbers, 

 (between 1-45) while those first introduced here are furnished with 

 numbers from that point on. This will make it easy to precisely desig- 

 nate a given measurement anywhere in the text, and to readily look up 

 its precise specifications in the list in which it is described in full. 



1 . Total cranial length; the ruler is to be applied to the craniogram, 

 holding the zero point on the most bulging point of the glabella. The 

 point of maximum length can be readily found by slightly rotating the 

 ruler about this anterior end, until the furthest distance is secured. 

 This should naturally correspond to the same, obtained by the crani- 

 ometer from the skull, allowance being made for the width of the pencil 

 mark at cither end, 1 mm. or so for each. 



