210 
A First Stiidij of the Burmese Skull 
i.e. nasion to bregma, lambda to opisthion, nasion to lambda, co-ordinates of breg 
matic subtense to NX, glabella to inion, co-ordinates of bregmatic subtense to GI; 
angles at glabella and nasion respectively, between chords to bregma and inion; 
angles of the fundamental triangle, at alveolar point, nasion and basion; profile 
angle or inclination to the horizontal of the line from nasion to alveolar point; 
and, lastly, the inclination of the basio-opisthionic line to the horizontal. 
The mean position in the type contour of the terminals of all these measure- 
ments had already been determined in some other vs'ay, so these were not used in 
building up the type contour. 
There were, however, four maximum subtenses also measured on the individual 
crania, and inserted in the type contour wherever the outline could reasonably be 
made to pass through them, which was generally the with the last-named 
measurements, points, whose mean position is obtained in one way, are not theo- 
retically bound to lie on a "mean" outHne obtained in another, though they will 
be very close to it. 
The maximum subtenses of which I have obtained the mean length and position 
are: maximum frontal subtense to nasio-bregmatic chord; maximum occipital 
subtense to opisthio-lambda chord; and maximum calvarial subtense, using nasio- 
lambda and glabella-inion lines respectively as base-lines. 
Max. frontal subt. 
to 
Max. occip. subt. 
to \0p. 
Max. subt. 
to N\ 
Max. subt. 
to GI 
X from N 
y 
X from X 
y 
X from N 
y 
X from G 
y 
6. On the Accuracy of Contour Values for the Determination 
OF Cranial Constants. 
It was promised in the last craniometrical paper published by this Laboratory* 
that the causes of discrepancies between contour and direct measurements should 
be investigated more closely with a view to the improvement of technique. 
I will deal first with those measurements alone which are given by the means 
of characters in the individual contours, not with those which are read off from 
the type contour and not used in its construction. 
I was hampered at the outset in my attempt to make the two methods of measure- 
ment give equal results by the fact that our contour tracer was no longer in quite 
good condition. Having been in frequent use for several years, the point of the 
scriber which is passed round the bone had been gradually worn down; and since 
one usually traces from left to right, it was not only slightly shortened, but rubbed 
away more on the right side (looking along the scriber towards the tip). The point 
* Biometrika, Vol. xi. p. 131 footnote. 
