62 yNIVERSITY OF MISSOURI BULLETIN 



facts, the facts of nature; and these definitions and these con- 

 ventions are only the tools, the instruments, with which these 

 facts are handled. Physics is essentially experimental. To 

 these conventions and definitions are added many experimen- 

 tal laws, but the whole is handled, arranged, and classified 

 with the aid of the fundamental laws. 



But let us discuss in more detail the scope of physics. 

 In the early classifications of this science men were forced 

 to divide it up into a number of distinct parts, each of these 

 parts seeming to be an almost independent subject. Later, 

 cases of interlinking were found and still later it was shown 

 that some of these subjects were really special cases of another 

 division. Today, although not logical, this natural division 

 has to a great extent been maintained. So that we now have 

 as the great divisions, Mechanics, Heat, Sound, Light, Elec- 

 tricity, and Magnetism. Mechanics, the first of these, is the 

 oldest. One of the earliest steps in the development of this 

 science was in the discovery of the laws of the lever by 

 Archimedes over 2000 years ago. In a narrow sense 

 mechanics may be defined as the systematic treatment of the 

 laws of motion of ordinary bodies and the effect of forces 

 upon their motion or their state of rest. The term mechanics 

 is often used in a broader sense to include the properties of 

 matter and the laws of liquids and gases. But this morning 

 I shall use the term in its more narrow sense. 



It was in the growth of this branch of physics that the 

 fundamental concepts and principles that I have been discuss- 

 ing were developed. It was in the solution of mechanical 

 problems that the laws of force and work originated. The 

 concept of energy and the doctrine of the conservation of 

 energy came from the study of the perceived motions of 

 bodies. For this reason, I shall hereafter refer to these as 

 the concepts and principles of mechanics. 



To these fundamental concepts and principles we have 

 discussed are added certain experimental laws. Attempt is 



