254 INTRODUCTION TO GENERAL SCIENCE 



b. Repeat (a), but go out to the fifth hole on one side. 

 Make a table of your results in (a) and (6). 



c. Try some original experiment with this lever, and write 

 out what you did and the results which you obtained. 



d. Describe a method of weighing ten pounds with a one- 

 pound weight and a stick. 



187. THE MUSCLES 



Movement, even with the joints, would be impossible, if it 

 were not for the muscles, which, by contracting or relaxing, 

 shorten and lengthen, thus moving the parts to which they 

 are attached. Muscles form the flesh, or meat, of animals, 

 and are the parts which are eaten as animal food. Exercise 

 hardens the muscles, and it can be readily seen that animals 

 intended for the food of man should not be allowed to exercise 

 more than enough to maintain their health. All muscles 

 work at a mechanical disadvantage. See preceding section. 



A uniform development of the muscles of our bodies is 

 desirable, and this can only be secured by regular and special 

 exercises. A person's usual employment generally develops 

 a certain set of muscles, and unless he artificially exercises 

 the other muscles, he is liable to become deformed. 



References : 



1. 1501 : 371-379. Muscles and Exercise. 



2. 1503:362-367. The Muscles. 



a. 1505:39-50. The Muscles. 



b. 1506 : 203-212. The Muscular System. 



c. 1507:273-288. Muscles. 



d. 1509 : 40-49. Muscles and Tendons. 



e. 1510:99-102. The Muscles. 



/. 1511 : 47-72. The Muscular System. 



