COMMON THINGS MAN. 



and laterally, sufficient for the purpose of locomotion, yet not too 

 great for stability. 



While the arm at the shoulder plays in an extremely shallow 

 socket, so as to give it all that vast range of motion which, is neces- 

 sary in an organ of prehension, but would be altogether incom- 

 patible with one of sustentation, the thigh bone is articulated at 

 the hip in a deep spherical socket, which looks obliquely down- 

 wards, and which rests upon the convex head of the bone with 

 sufficient firmness and solidity to afford a secure support to the 

 incumbent weight of the trunk, the upper members, and the head. 



14. The leg is articulated to the thigh at the knee by a hinge 

 joint, which enables it to be inflected backwards, so as to accom- 

 modate itself to a progressive motion. Unlike the hand, the foot 

 has no rotatory motion on the leg ; the two bones composing which, 

 firmly united together, confine between them the upper bone of 

 the foot, forming the ankles at either side of it. The foot thus 

 moves with a hinge motion on the ankle joint, projecting back- 

 wards at the heel, and still further forward in the direction of 

 the toes, so as to supply a large basis for the support of the body. 



The toes, unlike the thumb and fingers, are totally incapable 

 of prehension ; the great toe, which corresponds to the thumb, 

 instead of facing the others, is placed in juxtaposition with them, 

 and they cannot therefore be brought together so as to form, like 

 the fingers and thumb, a sort of pincers. 



The sole of the foot corresponds to the palm, and the instep to 

 the back, of the hand. The bones of the latter, extending 

 obliquely from the bend of the ankle joint to the commencement 

 of the toes, form an elastic arch, by which the blood-vessels, 

 nerves, and muscles of the foot are protected from the pressure of 

 the weight of the body, which would otherwise crush them. The 

 fleshy mass formed by the muscles and fat placed upon the sole 

 constitutes a cushion or buffer, which softens the collision which 

 must otherwise take place each time that the foot comes to the 

 ground, with the whole weight of the body upon it. 



15. Everything in the mechanical structure of the body con- 

 spires to prove that man was made to stand erect ; and with this 

 erect position are associated numerous consequences connected 

 with his superiority over other species. His feet are formed with 

 a base which is large in proportion to his body, so that the centre 

 of gravity can be easily kept vertically over it, a condition which 

 is essential to his stability. 'The legs, in their natural position, 

 are placed at right angles to the soles of the feet, and are therefore 

 vertical when the latter are horizontal. The centre of gravity of 

 the trunk is at some distance in front of the spinal column, and 

 would therefore have a tendency to incline forward, so that the 



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