PHYSICS 

 By Thomas Corwin Mendenhall, 



President of the Worcester Polytechnic Institute 



j^HE half-century during which the Smithsonian 

 Institution has existed will always be distin- 

 guished by reason of the extraordinary devel- 

 opment of the physical sciences which has 

 ■!^:*2^ occurred during that period. It is undoubtedly 

 true that at no other time in the history of the world have 

 the conditions of life been so seriously affected by the appli- 

 cations of scientific discovery. These are years that have 

 witnessed the perfected use of steam and steel, at sea and 

 on land, revolutionizing the methods of transportation of men 

 and merchandise. During the passage of these years the 

 various phenomena related to electricity have been magnified, 

 controlled, and directed in the interests of man, until the 

 results are little short of marvelous; and thus, by the use of 

 new forms of energy and material hitherto unavailable, all 

 nations and races are suddenly brought into relations with 

 each other of such unavoidable intimacy as to give rise to an 

 entirely new set of social and economical problems, the solu- 

 tion of which will demand the best efforts of the present and 

 future generations. In justice to the early half of the nine- 



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