414 Variation and Correlation of the Human Skull 
Alternative bars are provided in case these orifices are very small. On the base of 
the instrument is a pointed rod, which can be clamped in any position, and which 
enables the operator to fix a third point on the base of the skull. Spengler's 
pointer is merely a scriber, the horizontal awl or pointer of which can be set to the 
top line of the horizontal bars. It is then moved to the front of the skull, and 
this is turned round its auricular axis until the lowest point of the under rim of 
the eye-socket is in contact with the point of the awl. The skull is then held 
in this position by adjusting the pointed clamping rod attached to the base. 
A horizontal rod sliding on a graduated vertical bar attached to one of the 
supports of the "auricular axis," then gives the auricular height of the skull, that 
is, the vertical height of the skull measured perpendicular to the horizontal plane 
in a line perpendicular to the auricular axis. The goniometer is an instrument 
almost sufficiently described by its figure. It consists of two parallel horizontal 
bars terminating in points, which retaining their parallelism can be moved at will 
in a vertical plane. The points of these two bars can be brought into contact with 
any two points of the skull in one vertical plane. A rod can then be adjusted so 
as to be paralled to the line joining these two points, and the angle between this 
line and the horizontal is read off on a protractor scale attached to the instrument. 
The Franhfurter Verstdndigung defines the horizontal length — gerade Ldnge — 
of the skull as follows : 
Von der Mitte zwischen den Angenbrauenbogen, arms super ciliares, auf den Stirn-Nasenwulst, 
zu dem am meisten vorragenden Punkt des Hinterhaupts parallel mit der Horizontalebene des 
Schiidels gemessen. 
A footnote states that the measurement may be taken with the callipers or 
Spengler's craniometer, but the adjustment to the median and horizontal planes 
is not described. We adopted the following method which had been previously 
used by Professor Pearson for taking the horizontal length. The craniophor was 
placed in use upon a drawing-board covered with good millimetre ruled paper, the 
auricular axis of the instrument was adjusted so as to be parallel to the ruling. 
A solid truly vertical block made by the Cambridge Instrument Company was now 
brought in contact with the back of the skull and its bottom edge brought parallel 
to the ruling. This gave us a true vertical tangent plane to the skull parallel to 
the auricular axis. The Concordat says nothing about the measurement of the 
horizontal length, when the most projecting point of the back of the skull does not 
lie in the median plane. Such skulls frequently occur, and in such cases the 
horizontal length as above defined would be skewly measured. We have always 
taken it horizontal and perpendicular to the auricular axis. A similar block cut 
away above the base, but having a projection of the same thickness as the base 
and capable of adjustment to any position or height, was then brought in contact 
with the most projecting point of the forehead with one or both superciliary ridges, 
or the glabella* as the case might be, and its base made parallel to the auricular 
* A projecting edge on the front block allows the measurement to be always made from the glabella 
itself when this is preferred. 
