898 ADJUSTMENT OF THE CENTRE OF GRAVITY. 



all power of elevating the body : this is always the case when 

 we sit with the thighs and legs at right angles with each other. 

 Bend the knees to an acute angle, so that the feet are placed 

 under the body, and we rise with ease. 



When we wish to stoop forward without advancing one of 

 our feet, we acquire the power in a small degree, by placing 

 our hands behind us, to preserve the equilibrium. 



Some old persons, whose spines curve forwards in conse- 

 quence of age, bend their lower limbs, so that the pelvis may 

 be projected backwards beyond the centre of the base of the 

 body, and form a counterpoise to the upper part of the trunk. 



Bending the knees alone, without projecting the pelvis back- 

 wards, will not produce this effect ; for a person who stands 

 with his back tq a wall will bend his knees without obtaining 

 this advantage, while the heels and back part of the pelvis are 

 in contact with the wall. 



When we stand with the toes pointing directly forwards, the 

 base of the body is a square ; of which the feet are two of the 

 sides. As the positions of the feet are changed, the figure of 

 the base and its centre necessarily change also. When the feet 

 are placed one immediately before the other, the centre is be- 

 tween the toes of the one and the heel of the other. When 

 the position of the feet is such, that the toes point directly out- 

 wards, and the heels are opposite to each other, the centre of 

 the base is between the heels. 



In these cases, when the situation of the centre of the base is 

 changed, we immediately change the centre of gravity. Thus, 

 as we turn the toes outwards, the centre of the base moves 

 backwards, we, therefore, immediately make the body more 

 erect ; and by that means keep the centre of gravity over the 

 centre of the base. 



We move the centre of gravity laterally, as well as back- 

 wards and forwards, in conformity to this principle. 



Tlius, when we raise one foot from the ground, the body 

 inclines so much in the opposite direction, that the centre of 

 gravity is directly over the other. If the spine is diseased in 

 one spot, and assumes a lateral curvature, placing the centre of 



