INTRODUCTION 



15 



the swinging needle, which forms a plummet, may be readily ascertained. 

 Thus, in a skull placed in the Frankfort horizontal the means are here 

 at hand of determining the angle made by any surface, or by the line 

 joining any two points, with either this horizontal or with a plane at right 

 angles io it, such as the median sagittal, or any frontal plane. 



The accompanying figures (Figs. 8 and 9) will give suggestions as to 

 possible uses of this valuable little instrument, and no doubt others may 

 be devised by the reader. In all cases it will be noted that the angle 



FIG. 8. Attachable goniometer of Mollison used with the upper cross arm of the slide 



compass. (After Mollison.) 



indicated is that formed by the line connecting the two ends of the legs 

 of the compass with the vertical. 



Stationary Goniometer. A rather more special goniometer, especially 

 designed for getting any of the angles involved in the profile of a skull, 

 is the stationary goniometer (Fig. 10). This also is intended for use with 

 a skull placed in the FH,* and must itself be accurately leveled, and used 

 upon a horizontal table. For this purpose it is provided with leveling 

 screws and spirit levels in two planes. It is essentially a slide compass, 



* Frankfort Horizontal; this customary abbreviation for a constantly recurring 

 phrase will be employed throughout this book, cf. below, p. 38. 



