ARCHITECTURE OF THE SKULL 



17 



FIG. 3. 



there are some principles that are applicable to 

 the head. 



We see that the arch formed by the two parie- 

 tal bones is not a 

 perfect semicircle : 

 there is a projec- 

 tion at the centre 

 of each bone ; the 

 bone is more con- 

 vex, and thicker 

 at this part. 



The cause as- 

 signed for this is, that it is the point from which 

 ossification begins, and where it is, therefore, 

 most perfect. But this is to admit a dangerous 

 principle, that the forms of the bones are matter 

 of chance : and thence we are left without a 

 motive for study, and make no endeavor to com- 

 prehend the uses of parts. We find that all the 

 parts which are most exposed to injury are thus 

 strengthened, the centre of the forehead, the 



O f 



projecting point of the skull behind, and the 

 lateral centres of the parietal and frontal bones. 

 The parts of the head which would strike upon 

 the ground when a man falls are the strongest, 

 and the projecting arch of the parietal bone is a 

 protection to the weaker temporal bone. 



If we compare the skull to the centering, where 

 a bridge is to be built over a navigable river, and 



