20 HEAD. 



to this very danger. In most of the instances, the 

 structure has reference to other advantages, but it is 

 suited in every one to the advantage of which we are 

 now speaking. What have you learned upon this 

 subject ? 



A. The globe of the head is composed of S2veral 

 bones. They admit, at birth, of being easily separa- 

 ted ; and during youth and up to the period of man- 

 hood, the seams or joinings of the pieces are still loose. 

 Now, it is apparent that unless the union of the joints 

 of any vessel is absolutely solid, as much so as in any 

 other part, it must tend to prevent a ringing, or jar, 

 from extending through. Hence it is, that the slight- 

 est disunion in a piece of ware may be detected by a 

 stroke of the knuckle, which could not else be dis- 

 covered ; the flaw impedes the vibration, and this af- 

 fects the sound. There is reason to believe, that in 

 early childhood, especially during the lessons of walk- 

 ing, this is one cause why falls are borne with so 

 much impunity. (Arnott on the Elements of Phy- 

 sics.) But anatomists mention another security ; the 

 more curious, because it has so precise a resemblance 

 to a kind of precaution we adopt ourselves in similar 

 cases. The skull is lined within, like a soldier's steel 

 cap ; one advantage of which lining to the soldier is, 

 that it diminishes the jar occasioned by the sword, 

 and which \vould be capable of bringing him to the 

 ground without any penetration by the weapon. The 

 effect may be seen in a wine glass, which will not 

 ring if W T C but touch our finger upon the cup. There is 

 the same principle of security in the bony case, which 



