206 NATURAL THEOLOGY. 



of the harder portion of wood increases this pro- 

 perty of resistance. With this fact before us we 



liM 



A 



may return to the examination of the spine of bone. 

 We see that it is calculated to resist pressure, 

 first, because it is further removed from the centre 

 of the cylinder, and, secondly, because it is more 

 dense, to resist compression, than the other parts 

 of the circumference of the bone.* 



This explanation of the use of a spine upon a 

 bone gives a new interest to osteology. The ana- 

 tomist ought to deduce from the form of the spine 

 the motions of the limb, the forces bearing upon 

 the bone, and the nature and the common place of 

 fracture ; while, to the general inquirer, an agree- 

 able process of reasoning is introduced in that de- 

 partment, which is altogether without interest 

 when the " irregularities " of the bone are spoken 

 of, as if they were the accidental consequences of 

 the pressure of the flesh upon it. 



Although treating of the purely mechanical prin- 

 ciple, it is perhaps not far removed tVom our proper 

 object to remark that a person of feeble texture 



* As the line A B extends furtlier from the centre than B C, on 

 the principle of a lever, the resistance to transverse fracture will 

 be greater in the direction A C than B C. 



