C. D. Fawcett 
415 
axis by means of the millimetre paper. The horizontal length of the skull was 
then determined by measuring with a millimetre scale the distance between the 
bases of the vertical blocks. This was measured on both sides of the blocks to 
insure that they were truly parallel. It will be seen that this measurement 
diverges somewhat from the gerade Ldnge of the Frankfurt Concordat. But the 
gerade Ldnge as measured by the German craniologists with the callipers, the eye 
judging of the horizontality of the instrument, seems to us liable to an error of 1 
to 2 millimetres — an error of the same order as the thickness of the superciliary 
ridges. Taken with the callipers in nine cases out of ten it will be found to agree 
with the German horizontal length, and in the tenth it is very difficult to deter- 
mine whether the difference is due in part or not to the hand in holding the 
callipers. The length determined by aid of the blocks described above would be 
the exact horizontal length of the skull, if photographed to life size by a camera 
on the auricular axis at a considerable distance, or it would be the horizontal 
length of a projection on a plane perpendicular to the auricular axis made by 
a line parallel to that axis and moving round always in contact with the surface 
of the skull. We shall consider below what differences there are in mean and 
variability, of the length of the skull as measured in the three different ways*. 
Finally attention may be drawn to the spanner used, which is rectangular in 
shape and graduated on three sides. It was devised by Professor J. Ranke 
but is a modification of Virchow's spanner. Diagram matically it consists of three 
rods ABCD, of which CD can be pulled out to D' so that AD' is parallel to BC, 
and further CD can be slid parallel to AB along BC. 
Thus by taking BC parallel to any given direction it is possible by one adjust- 
ment to determine the distance between AD resolved along and perpendicular to 
this direction, i.e. we can read off BC and DD'. By this instrument the vertical 
difference in height of points not necessarily in the same vertical line can be 
obtained with considerable accuracy. In addition to these instruments we used 
a steel tape and a small pair of callipers. 
* Measurements by Mr A. Martin Leake showing how slight are the differences produced by using 
the English or German methods are cited by Pearson : The Chances of Death, Vol. i. p. 270. 
