THE HUMAN SKELETON. 69 



and ingenuity, is not formed on principles so correct, as those 

 which have directed the arrangement of the bones of the feet ; 

 that the most perfect pillar is not adjusted with the accuracy 

 of the hollow bones which support our weight ; that the in- 

 sertion of a ship's mast into the hull is a clumsy contrivance 

 compared with the connexions of the human spine and pel- 

 vis ; and that the tendons are composed in a manner supe 

 rior to the improved chain cables of Bloxham. 



13. As the head is the noblest part, and the brain the 

 most essential organ of the animal system, let us first direct 

 our attention to it. The brain is liable to injuries, not only 

 by sharp bodies touching and entering it, but by a blow upon 

 the head, which shall vibrate through it, without the instru- 

 ment piercing the skull ; and such a blow would more effec- 

 tually destroy a man's senses, than even if a sword pene- 

 trated into its substance. It is obvious, that if the bony 

 case were soft it would be easily pierced ; if of a brittle 

 nature, it would be easily cracked, and if very firm and solid, 

 like metal, it would ring and vibrate, and thus communicate 

 the concussion to the brain. 



14. To obviate these dangers,(we find the skull composed 

 of two plates of bone, one external, which is fibrous and 

 tough, and one internal, so dense and hard, that it is called 

 by anatomists the glassy tdble% Now, as the brain is liable 

 to be hurt both by sharp and blunt instruments, the inner 

 table is hard and brittle, calculated to resist any thing pene- 

 trating ; while the outer table is tough to give consistence, 

 and stifle the vibration which would take place, if the whole 

 texture were uniform. This may be illustrated by an ex- 

 ample. If a soldier's head be covered with a steel helmet 

 or cap, the blow of a sword, which does not penetrate, will 

 yet bring him to the ground ; but if it be lined with leather 

 and covered with hair, the vibration is not transmitted to 

 the brain, and the wearer escapes without injury. 



