NATURAL THEOLOGY. 



103 



[Since it has been our author's pleasure 

 to take this instance, the figure will illus- 

 trate his description. A is the lower part of 

 the arm-bone, or humerus; B is the ulna 

 and C the radius, the two bones of the fore- 

 arm. It will be understood how these bones, 

 being tied together by ligaments, hinge and 

 move upon the humerus A ; c being the pro- 

 cess of the ulna, on wliich we rest when 

 leaning on the elbow. By applying our 

 hand to the arm, we at once feci the freedom 

 with which the bone moves in bending and 

 extending the arm. — When we turn the 

 key in a lock, or make the guards in fencing 

 by the motion of the wrist, the ulna B is 

 stationary, and the radius C turns round 

 upon the head of the bone at d and e, carry- 

 ing the hand with it. The rest is abundantly 

 well explained in the text.] 



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t ached rolls upon the first, by the help of a groove 

 or hollow near each end of one bone, to which is 

 fitted a corresponding prominence in the other. If 

 both bones had been joined to the cubit, or upper 

 arm, at the elbow, or both to the hand at the wrist, 

 the thing could not have been done. The first 



