M. L. TiLDESLEY 
211 
of the scriber is therefore not immediately above the point of the ink-container; 
but a little behind and to the left of it; with the result that a point on the skull 
will be projected a little in front of and to the right of its true position: 0-3 mm. 
in front and O-i mm. to the right, the hypotenuse of the triangle giving us 0-5 mm. 
displacement of the actual point. 
When the scriber is moved round the skull in tbe usual direction, i.e. left to 
right, making an angle of about 60° with the direction in which it is travelUng, 
the whole 0*5 mm. displacement operates to tlirow the traciiig H>il/dn- its true position. 
Thus, in taking a measurement from one side to another of the tracing or wherever 
the positions of the scriber have been approximately parallel but in the opposite 
sense, one gets a result which is about 1 mm. less than the same measurement 
taken direct on the skull. 
That the Klaatsch contour tracer had to be used with this defect, was a state 
of affairs due to the war. It was impossible to get the instrument over to the makers, 
and skilled instrument-makers here were too much occupied with other work to do 
this repair properly. 
In comparing contour and direct measurements, however, I was aware of a 
certain discrepancy for which this instrumental defect did not wholly account. 
Further investigation revealed another source of error in the drawing-board on 
which the tracing was done. This was found to be slightly warped, in such a way 
that when the Klaatsch was tracing the top and base of the skull in the sagittal 
and transverse contours, and the sides in the horizontal contours, the instrument 
was tilted shghtly away from the skull. As nearly as I can estimate it this tilt is 
only about 0-5° along each of the two long sides of the board, but at the height at 
which the scriber is placed during most of the contour tracing, this suffices to 
throw its tip about 0-5 mm. backwards, and consequently the Une traced about 
0*5 mm. within its true position*. Where this operates on two opposite sides of the 
tracing, we get maximum shortening of about 1 mm. on this score. 
We will now proceed to the comparison of our actual results. 
Burmese mean Glabellar-Oecipital Length. 
Types: 
Males 
Females 
A 
B 
C 
A 
B 
C 
From direct 
measurements 
From sagittal 
contours 
173 o (44) 
172-0 (44) 
173- 8t (8) 
174- 4 (7) 
176-7 (8) 
17.5-5 (8) 
166-5 (38) 
165-7 (39) 
163-8 (17) 
102-8 (17) 
170-2 (18) 
169-1 (18) 
* I fully admit that the jjossibility of such a defect should have occurred to me before the board 
was used. As, however, it was not realised till afterwards, when the long process of contour-drawing, 
ruling, measuring and averaging the measurements was comj)lete and could not be repeated, it has had 
to remain uncorrected. 
t For the seven skulls contoured, mean of direct measurements is 175-8. 
