46 ANIMAL MECHANICS 



a buttress, all these delicate fibres converge, or 



point from the head and neck of 

 the bone, which may be rudely 

 represented in this way. 



We may here notice an opin- 

 ion that has been entertained, in 

 regard to the size of animals. It 



o 



is believed that the material of 

 bone is not capable of support- 

 FlG - 10 - ing a creature larger than the 



elephant, or the mastodon, which is the name of 

 an extinct animal of great size, the osseous re- 

 mains of which are still found. This opinion is 

 countenanced by observing that their bones are 

 very clumsy, that their spines are of great thick- 

 ness, and that their hollow cylinders are almost 

 filled up with bone. 



It may be illustrated in this manner : A soft 

 stone projecting from a wall may make a stile, 

 strong enough to bear a person's weight ; but if 

 it were necessary to double its length, the thick- 

 ness must be more than doubled, or a freestone 

 substituted ; and were it necessary to make this 

 freestone project twice as far from the wall, even 

 if doubled in thickness, it would not be strong 

 enough to bear a proportioned increase of weight : 

 granite must be placed in its stead ; and even the 

 granite would not be capable of sustaining four 

 times the weight which the soft stone bore in the 



