A Sketch of his Work as a Craniologist. 39 



another, adopting the same axis as a centre, being indicated upon 

 the graduated circle J by its index K. In this manner mesial 

 measurements, mathematically accurate, both as regards extension 

 and position, may be taken with surprising facility. For the 

 reasons already advanced, however, it has been found to be much 

 preferable to make outline tracings instead, which may be accom- 

 plished with very little additional trouble. To do this — replace E 

 in the position it occupies in the diagram ; set A free by removing 

 the pin from R, and then carefully move Q round P as a centre ; 

 keeping, at the same time the tracer W in contact with the skull, 

 and tracing upon the paper Y, with the pencil U, the course the 

 latter takes, which will coincide exactly with the line described by 

 the point of W in its progress ; the position of sutures, and other 

 important points, being indicated as we proceed by short lines 

 perpendicular to the skull. By this means we shall succeed in 

 producing a faithful outline of the entire median section of the 

 skull ; and may, in like manner, produce transverse sectional out- 

 lines at any desired point, by simply replacing E in the horizontal 

 position, and by rotating G, bringing the section to be outlined 

 into the same horizontal plane as the point of the tracer W. A 

 series of outlines thus taken (see Plates 2 and 3), affords per- 

 manent and unimpeachable materials from which measurements may 

 be taken with perfect accuracy and facility ; and I shall now 

 proceed to explain how the exact dimensions, and the more 

 prominent characteristics of the skill, maybe expressed numerically, 

 with the precision and fidelity necessary for scientific purposes. 



