LOCOMOTION. [CHAP. vn. 



Muscular actions associated to produce an attitude are styled co- 

 ordinate. They conspire in obedience to the particular organization 

 of the nervous arid muscular systems ; and the resulting postures 

 are natural, and perfectly accordant with the wants and habits of 

 the species. Most attitudes, if perfectly natural, are graceful; just 

 as external figure is graceful ; unnatural attitudes are more or less 

 constrained, or awkward. The co-ordinate, like other movements 

 of the voluntary muscles, are liable to be influenced by passions and 

 affections of the mind. Hence the internal commotions of the soul 

 betray themselves in the attitudes of the body as surely as in the 

 lineaments of the countenance. 



In considering the different attitudes, it is to be remembered that 

 the human body is not withdrawn, either by its organization or vital 

 endowments, from the operation of the general laws of matter ; and, 

 accordingly, that the muscular actions occurring within it are all 

 adapted to act upon its several parts, as upon masses of certain 

 shapes, sizes, and weights. In all attitudes the centre of gravity 

 must be maintained within the base of support. 



In standing, the base of support is the space included between 

 the extreme points of the feet. The feet are separated, and the 

 toes turned outwards to increase it. If the body be pushed aside, 

 the foot is instantly carried under it, or it falls : and if motion be 

 unexpectedly given to the feet, while the body remains at rest by 

 its inertia (as when a boat in which we are standing is suddenly 

 shoved from off the shore), the body falls. In standing upright, 

 both legs are kept extended, and the spine and head erect ; if the 

 muscles that effect this be suddenly paralysed, as when a man is 

 shot dead, the head droops on the chest, the curves of the spine are 

 increased by the pressure of the superincumbent weight, and the 

 whole trunk approaches the ground by bending the joints that were 

 before extended. 



The muscular action required to maintain the erect posture of the 

 body is very great. This is shewn by the fatigue that ensues on an 

 attempt to remain perfectly still in the erect posture, even for a 

 very short time. In fact, though we can stand long at a time, it 

 is only by frequently relieving one set of muscles, and bringing 

 another into play, as every one may convince himself by attention 

 to his own case. We throw the weight of the body first on one leg, 

 then on the other ; we change the position of the feet, and of the 

 ankle, knee, and hip joints, as well as of the rest of the body. 



Under all these movements, the centre of gravity has to be kept 

 within the basis of support ; and, to effect this object, the different 



*ent 



