SUPPOHT OF THE BODY. 



49 



balance. Thus it will be observed that in preserving the 

 erect posture, the muscles principally act in steadying the 

 body, but have little of its weight thrown on them; and this 

 is exceedingly important, as muscular contraction is a vital 

 action involving expenditure of force, and very exhausting. 



Fig. 27. Illustrates the preservation of the centre of gravity 

 within the basis of support. . 



The body is supported with still less muscular effort in 

 the position called standing at ease than at attention. In 

 standing at ease the weight is borne principally on one foot, 

 while the other assists lightly as a prop. The limb on which 

 support is made has the knee straight, and is inclined above 

 towards its own side, so as to bring the weight of the trunk 

 over the foot; the haunch of the other side is allowed to 

 drop to a lower level than its fellow, sending the lower end 

 of the vertebral column into an oblique position; and the 

 trunk is kept vertical by the column being thrown into a 

 spiral curve. 



When a heavy weight is carried in front of the body, 

 the trunk is thrown sufficiently back to bring the centre 

 of gravity of the whole mass within the basis of support ; 

 for this reason portly persons, in whom the weight of 

 the abdominal region is greatly increased, hold themselves 

 H D 



