NATURAL THEOLOGY. 119 



hip. The thighs must have been kept constantly 

 together, and the legs had been loose and strad- 

 dling. There would have been no use, that we 

 know of, in being able to turn the calves of the legs 

 before ; and there would have been great confine- 

 ment by restraining the motion of the thighs to one 

 plane. The disadvantage would not have been less, 

 if the joints at the hip and the knee had been both 

 of the same sort ; both balls and sockets, or both 

 hinges : yet why, independently of utility, and of a 

 Creator who consulted that utility, should the same 

 bone (the thigh-bone.) be rounded at one end, and 

 channelled at the other ? 



The hinge-joint is not formed by a bolt passing 

 through the two parts of the hinge, and thus keep- 

 ing them in their places, but by a ditfe rent expedient. 

 A strong, tough, parchment-like membrane, rising 

 from the receiving bones, and inserted all round the 

 received bones a little below their heads, encloses 

 the joint on every side. This membrane ties, con- 

 fines, and holds the ends of the bones together,keep 

 ing the corresponding parts of the joints — {. e., the 

 relative convexities and concavities — in close ap- 

 plication to each other. 



For the ball and soclict-joint, beside the mem- 

 brane already described, there is in some important 

 joints, as an additional security, a short, strong, yet 

 flexible ligament, inserted by one end into the head 

 of the ball, by the other into the bottom of the cup, 

 which ligament keeps the two parts of the joint so 

 fii'mlv in their nlace. that none of the motions which 



