190 THE HUMAN MACHINE 



where muscles might be attached, jn each case seek a place for 

 attachment for the other end of the muscle. 



Conclusion. 1. Write a statement giving three general uses of 

 the human skeleton. Take a special bone or bones to illustrate 

 each use. 



2. Compare the skeleton with the figure on page 268, Civic 

 Biology. Make a drawing to identify the principal bones. 



Problem 167 : To fund the relation of muscles to bones in the 

 human body. 



Method. Using the diagrams in your Civic Biology, page 269, 

 work out the different classes of levers. 



Observations. In the human body which class of lever is 

 represented when we raise a weight in the hand ? What kind of 

 lever do we use when we rise on the toes? What kind of lever 

 do we use when we nod the head? 



Conclusion. 1. Prove that three classes of levers are present 

 in the human body. 



2. Find another example of each kind of lever in the human 

 body. 



Problem 168 : To study the joints of the human body. 



Materials. Human skeleton. 



Method. Study the following joints in the human skeleton : 

 arm at shoulder, knee, head on neck bones, bones of spinal 

 column. Move them in each case. 



Observations. Is the joint hinge-like, ball and socket, gliding, 

 or rotary ? 



Conclusion. 1. How many different kinds of joints can you 

 find in a skeleton? 



2. What are their specific uses? 



Problem, 169 : To get a preliminary survey of the internal 

 structure of the human body. 



Materials. Manikin and charts showing organs of the human 

 body. 



Observations. If we compare the human body to a machine, 

 then the bones and muscles are the framework. Within the body, 



