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will be best understood with the aid of the an- 

 nexed diagram. A, A, represent the top and 

 bottom, and B, B, the ends of the instrument, 

 dovetailed into each other to prevent warping. 

 C, C, C, are sliders and screws, the latter being 

 fitted with collars on each side of the sliders where 

 they pass through it, in order that the screw may 

 carry the slider along with it when moved back- 

 ward and forward, D, cranium to be measured. 

 E, F, is an iron straight-edge, standing on two 

 legs welded to it and filed to the same length, so 

 that when they rest on a horizontal plane, the straight-edge is also horizontal. G 

 is a rod attached to a float of cork, small enough to drop into the foramen magnum; 

 it is cut to such a length that when the base of the float is raised to the level of the 

 plane on which rest the legs of the straight-edge E, F, the top of the rod shall 

 rise to the upper margin of the straight-edge. H is an oval hole cut in the top of 

 the frame A, (which is of stout mahogany plank,) large enough to admit the free 

 adjustment of the largest cranium. In the lower figure^ c, is the screw moving 

 the slider a, a, the former, when in place, working into a nut through a hole in 

 the mahogany top-piece. 6?, d^ are clamps to confine the slide in a regular direc- 

 tion: /, the point of the slider as shown in the lower figure, is bevilled off* on 

 the top and two sides ; but the low^er side of the slider is carried out straight to 

 the point, which is thus kept in the same plane as the top of the frame on w^hich 

 it is bound by the pinching-screw 6, tapped into the clamp nearest the point of 

 the slider. 



Capacity of the coronal region, — This measurement is the space included 

 betw^een an imaginary plane drawn through the centres of ossification of the 

 parietal and frontal bones, and the inner surface of the portion of cranium above 

 it. To obtain this measurement, the instrument was first adjusted so as to bring 

 the top of the frame A, A, to coincide with the plane of the horizon. The sutures 

 and small foramina on the top of the skull being stopped with wax or putty, and 

 when necessary, the inside of the cranium having been well varnished, the centres 

 of ossification of the parietal bones were marked with a cross, and a line was 

 drawn between the centres of ossification of the os frontis : the cranium was then 

 placed inverted in the oval hole H, and the point of the slider at the end of the 

 frame being pressed against the drawn line between the centres of ossification of the 



