68 PHYSIOLOGY. 



9. If we compare the human body, as a work of art, with 

 any forms of human architecture, how vastly superior does 

 it appear. A watch, or a musical automaton are highly in- 

 genious specimens of inventive skill; but where is the 

 watch or the automaton that can, without repair, for the 

 space of 80 or 100 years, continue to perform its movements 

 with regularity and precision. And yet how much less 

 complicated is their machinery, how vastly more solid, and 

 durable the materials out of which they are formed ! 



10. If we examine a ship, we find it built for passive mo- 

 tion, and for resisting force externally applied ; a house or a 

 bridge is constructed for solidity and firmness, on the prin- 

 ciple of gravitation ; a railroad car is built for rapid motion, 

 and its wheels so adjusted, that they may not run off the 

 track ; but in the human body, we find not only securi- 

 ties n gainst the gravitation of the parts, provisions to with- 

 stand shocks and injuries from without, but at the same time, 

 the frame work is calculated to sustain an internal impulse 

 from the muscular force which moves the bones as levers, or 

 like a hydraulic engine, propels the fluids through the body. 



11. The human fabric is admirably adapted to resist the 

 influences to which it is subjected ; in other words, there is 

 a nice balance between the power of exertion and the capa- 

 bility of resistance. A deer or a giraffe is never injured by 

 any leap which their muscular powers enable them to make, 

 because the inert power of resisting the shock, bears a rela- 

 tion to the muscular power with which they spring ; and so 

 it is in man. The elasticity of his limbs is proportioned very 

 accurately to his activity ; he readily resists shocks and im- 

 pulses upon the lower extremities, because they are adapted 

 to this end ; but if the same are applied to the upper, the 

 bones are broken or displaced, because they are adapted 

 rather for extensive and rapid motion, than for resisting vio- 

 lent shocks. 



12. It has been truly remarked that the foundation of the 

 Eddystone light-house, the perfection of human architecture 



