PHYSICAL SCIENCE 



CHAPTER I 



INTRODUCTION 



Not clinging to some ancient saw ; 



Not mastered by some modern term ; 



Not swift nor slow to change, but firm : 

 And in its season bring the law. 



—Tennyson. 



In the early years of the twentieth century, when 

 this book was first published, physical science was 

 developing mainly In two directions. Although 

 these movements were contemporaneous, it is In- 

 teresting to note that the methods used by the 

 two schools of research were, to some extent, 

 the expression of opposite tendencies. 



On the one hand, we traced the growth of the 

 study of the conditions In which all physical and 

 chemical change In a system must cease — the 

 conditions of physical and chemical equilibrium. 

 This growth was due to the thermodynamic 

 methods founded chiefly on the great work of 

 the late Willard Gibbs, of Yale University in 

 the United States. On the other hand, our 

 knowledge of the mode of the conduction of 

 electricity through gases was extended, mainly 

 by the efforts of Sir Joseph John Thomson, 

 Professor of Experimental Physics at Cambridge, 

 and now Master of Trinity, and of the band of 



1 B 



