THE HINGES. 93 



plain that we could never have stood firmly ? 

 In like manner, how very inconvenient it would 

 be, to have our finger joints move one way as 

 well as another? On the contrary, how con- 

 fined and cramped would have been the mo- 

 tions of the arm, if the shoulder had been like 

 the knee, and had only permitted the arm to 

 swing backwards and forwards, without our 

 being able to carry it outward from the body ? 



The builders of machines have sometimes 

 made joints in their machinery very much like 

 the shoulder joint ; but it is doubtful whether 

 they could ever have contrived them, if they 

 had not first looked at the bones of man, or 

 some other animal ; for other animals have 

 these various sorts of joints, as well as man. 



LIGAMENTS. But how are the joints held 

 in their place ? For when we take up a bone 

 which has lain, perhaps for years, bleaching in 

 the sun and rain, we only see the ends smooth, 

 and some of them hinge-like ; and if we take 

 up two such bones, and put them together, 

 they will not stay in that condition a moment, 

 unless they are fastened by strings or wires, or 



