It is necessary to use the double square. The horizontal branch is placed tangent to the vertex, its direction should be perceptibly parallel to the transverse orbital line, the graduated vertical branch should pass over the auricular foramen. The required number may be read, corresponding to the point of the tragus.
The height of the cranium is exceedingly important; its variations produce variations in the physiognomy.
In the first period of childhood, the cranium is very low in comparison to its width; this is also true of dwarfs. In these cases the width of the cranial vault is large in comparison to that of the base; a low cranium bulging above is distinctive of babies and dwarfs.
In the adult this diameter measures from 130 to 140 mm.
Among the other measurements which an taken on the cranium, the following may be cited:
The antero-posterior metopic diameter: from the metopic to the occipital point. In children it is sometimes the maximum longitudinal diameter.
The ophryo-iniac diameter from the ophryon to the inion.
The minimum frontal diameter: between the two minimum frontal points.
The maximum frontal diameter: between the two external orbital apophyses.
The bistephanic diameter: between the two stephanic points.