THE HUMAN FRAME 79 



OF THE JOINTS. 

 I. The above are a few examples of bones made remark 

 able by their configuration ; but to almost all the bones he- 

 long joints; and in these, still more clearly than in the form 

 or shape of the bones themselves, are seen both contrivance 

 and contriving wisdom. Every joint is a curiosity, and isi 

 also strictly mechanical. There is the hinge-joint, and the 

 mortise-and-tenon joint ; each as manifestly such, and as 

 accurately defined, as any which can be produced out of a 

 cabinet-maker's shop ; and one or the other prevails, as 

 either is adapted to the motion which is w^anted : for exam- 

 ple, a mortise-and-tei^on, or ball-and-socket joint, is not re- 

 quired at the knee, the leg standing in need only of a motion 

 backward and forward in the same plane, for which a hinge- 

 joint is sufficient ; a mortise-and-tenon, or ball-and-socket 

 joint is wanted at the liip, not only that the progressive step 

 may be provided for, but that the interval between the limbs 

 may be enlarged or contracted at pleasure. Now observe 

 Mdiat would have been the inconveniency — that is, both the 

 superfluity and the defect of articulation, if the case had 

 been inverted — if the ball-and-socket joint had been at the 

 knee, and the liinge-joint at the hip. The thighs must have 

 been kept constantly together, and the legs had been loose 

 and straddling. 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 confinement 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 sock- 

 ets, or both hinges ; yet why, independently of utihty, and 

 of a Creator who consulted that utility, should the same 

 bone — the thigh-bone — be rounded at one end, and chan- 

 nelled at the other? 



The hinge-Joint is not formed by a bolt passing through 

 the two parts of the hinge, and thus keeping them in their 

 places, but by a difierent expedient. A strong, tough, parch- 



