312 THE PRINCIPLES OF SCIENCE. 



that events will long continue to happen as they have 

 previously happened. 



We have now pursued the theory of inductive inference, 

 as far as can be done with regard to simple logical or 

 numerical relations. The laws of nature deal with time 

 and space, which are indefinitely, or rather infinitely, divi- 

 sible. As we passed from pure logic to numerical logic, 

 so we must now pass from questions of discontinuous, 

 to questions of continuous quantity, encountering fresh 

 considerations of much difficulty. Before, therefore, we 

 consider how the great inductions and generalizations of 

 physical science illustrate the views of inductive reason- 

 ing just explained, we must break off for a time, and 

 review the means which we possess of measuring and 

 comparing magnitudes of time, space, mass, force, mo- 

 mentum, energy, and the various manifestations of energy 

 in motion, heat, electricity, chemical change, and the other 

 phenomena of nature, 



