CHAPTER IV. 



PRIMAKY FORCES. 



TTTE have seeu ^ that all energy has its origin in force : 



' ' for instance, the force of gravity produces the energy Force 

 of motion of a falling body. And as all forms of energv o^'^S^^*^*/^ 



° •' o^ energy, but 



are capable of mutual transformation, it follows that any 

 force may produce any form of energy. If gravity causes 

 a body to fall, and in its descent it produces electricity or 

 heat by friction, there is electricity or heat produced by 

 gravity. But the converse is obviously not true ; gravity 

 may produce motion, but motion cannot produce gravity : energy 

 chemical affinity may produce electricity or heat, but ori^^nate 

 neither electricity nor heat can produce chemical affinity, primary 

 The ultimate origin of all energy is in primary forces ; and 

 primary forces are defined as forces which do not originate Primary 

 in any other forces, but are to be directly referred to the ^^IX ^' 

 laws of nature, and have their origin directly in creative 

 power. 



Thus the attractive and repulsive forces of a magnet or Instances 

 of an electrised body are not primary forces, because they not mT-^ 

 are not to be referred to the ultimate properties of the mary. 

 bodies. The electrical attractions and repulsions of a body 

 that has been electrised by a common electrical machine 

 are due to the charge of electric energy which the body 

 has taken up ; and this electric energy has been obtained 

 by the transformation of the mechanical energy that 

 worked the machine.^ And the magnetic attractions and 

 repulsions of an iron bar that is magnetised by the passage 



P. 19. 2 p 30 



