- ANATOMICAL MEASUREMENTS. 255 



frontal bone, the sliders at the sides of the instrument are then brought in contact 

 with the centres of ossification of the parietal bones, the slider at the end being 

 moved backward or forward to bring the cranium into the proper place. The 

 float C is then dropped into the foramen magnum, and the frame E, F, held over 

 it, as shown in the figure : mercury is then poured into the cranium until the top 

 of the float-rod rises to the straight-edge E, F, thus indicating the surface of the 

 mercury to stand at the level of the top surface of the frame A, A; and as the 

 adjustment of the centres of ossification to the points of the sliders has brought 

 them into the same plane as the top of the frame, the surface of the mercury must 

 coincide with an imaginary plane, drawn through the centres of ossification. The 

 mercury is then transferred to a graduated glass tube, and the capacity of the 

 coronal region read off* in cubic inches and parts. 



The sub-coronal region is obtained by deducting the capacity of the coronal 

 region (obtained as above stated) from the total capacity. 



Capacity of the anterior chamber of the cranium, — This measurement is the 

 capacity of the space contained between an imaginary plane, at right angles to the 

 anterior and posterior diameter of the cranium, coinciding with, or let fall from 

 the anterior margin of the foramen magnum, and passing at right angles through 

 the imaginary plane (drawn through the centre of ossification) which formed the 

 dividing line between the coronal and sub-coronal regions. It is thus taken : the 

 cranium being placed in the frame exactly as in taking the capacity of the coronal 

 region, the straight-edge of a slip of wood is laid across it over the anterior margin 

 of the foramen magnum and at right angles to the anterior and posterior diameter 

 of the skull. One side of a carpenter's square is then laid on the mahogany 

 surface, so that the other side of the square, which would then be upright, would 

 stand with its flat surface pressing against the side of the cranium ; and another 

 square is adjusted in the same manner on the other side of the skull, each having 

 one of their vertical edges pressing against the straight edge of the ruler laid over 

 the anterior margin of the foramen magnum ; and a pencil mark is drawn on each 

 parietal bone along the perpendicular edges of the squares adjusted to the straight 

 edge ; these pencil marks will be at right angles to the plane passing through the 

 centres of ossification, and indicate the position of the plane dividing the anterior 

 and posterior chambers, as described in the definition of that capacity. The cra- 

 nium is then taken from the instrument, and a hole, eighth of an inch in diameter, 

 drilled through the pencil marks in each parietal bone, about two inches from the 

 meatus auditorius : a piece of stiff*, straight wire is then passed through these two 

 holes, and the cranium nearly filled with white pepper seed. The skull is then 



