32 



HITCHCOCK'S ANATOMY 



Fig. 30. from Fig. 30, which is a human 



Fibula tied in a knot after hav- 

 ing been immersed for some 



JA 82. Mechanical Construc- 



r v ' ; ; t ion of Cones, — As a general 



law the extremities are the 

 largest, and the bodies or shafts 

 are smooth and of a uniform 

 surface. They are in most 

 ll^BHISPi^&l cases so constructed as to give 

 lXy the greatest strength and sup- 



port, and at the same time fur- 

 nish as little weight as possible. 

 Hence the long bones are most- 

 ly hollow, or have an arched 

 form, while the flat bones are 

 portions of a circle or sphere. In the face also the bones are 

 not all solid, but some of them contain large cavities, so that 

 firm attachment may be given to the muscles, and protection 

 to the more delicate parts. 



83. Average Weight of adult Skeleton, — The weight of 

 the skeleton is as 10.5 : 100, or about one tenth the weight 

 of the whole body. And since the average weight of an adult 

 man is 136 pounds, the weight of an adult skeleton is about 

 13.5 pounds. 



84. Strength of Bones. — The power of the human bones 

 as levers when compared with different substances is remark- 

 able, as is seen by the following table. 



Freestone (sandstone) 1. 



Lead 6.5 



Elm and Ash (wood) 8.5 



Box, Yew, and Oak 11. 



Human Bone 22. 



82. Which part of the bones is generally the largest? Why are many of the bones 

 hollow or partially so ? 83. Give the weight of the human skeleton. What is its pro- 

 portion to that of the whole body ? 84. Give the comparative strength of the bones. 



