NATURAL THEOLOGY. 109 



venience of a wooden foot r ; and the inconvenience 

 would be, it would have no spring ; and would be in- 

 capable of suiting its shape to the inequalities upon 

 which we stand or walk. But the number of bones 

 is only a part of this admirable mechanism. The 

 arching of the foot is an obvious proof of contrivance. 

 If the bottom of the foot was perfectly flat, it is plain 

 it must have had a heavy and uncomfortable effect. 

 One may easily perceive this, by lashing the bottom 

 of the foot to a strip of wood. There could be no 

 spring with a flat foot. But as the construction is, 

 the two extremities only of the foot rest upon the 

 ground, while the elastic arch in the centre yields to 

 the pressure, and causes the weight of the body when 

 we walk, to play, as it were, upon a constant spring. 



B. We now see the use of the heel, and it is 

 a use which one would not immediately think of. It 

 helps to form the arch. 



T. But this is not all the use. 



A. The heel is not directly under the leg, but ex- 

 tends back like a spur, and is united to the main body 

 of the foot, by a very firm, but still a considerably 

 springy joint. The effect of this is, when the heel 

 touches the ground in walking, and it touches first, 

 in consequence of its being formed like a spur, and 

 having a spring at the same time, the whole weight of 



the body does not come down with a sudden jolt ; 



there is not only a yielding in the point of support, 

 but we descend in a curve, the centre of which is the 

 ball of the heel. If it were not for this contrivance- 

 K 



