SIMPLE LESSONS FROM COMMON THINGS 405 



electric fluid. They are a component of every atom of every kind of 

 matter. We have only to rub any two unlike pieces of matter together, 

 and one of them takes this negative fluid from the other. The piece of 

 matter which has lost the electric fluid is said to be positively electrified. 

 One question before us to-day is this : Should not this positively electri- 

 fied matter be called positive electricity? It seems certain that there 

 is no positive electrical fluid, and that there is no positive electrical 

 current. What we have been calling the negative current is then the 

 real current. It flows through our trolley wires and lights our cities. 

 In other words, it seems very probable that all matter is composed of 

 a combination of positive and negative electrical particles. 



It is also certain that the positive and negative electrons are by no 

 means simple in their structure. They are in some way linked with 

 each other through the agency of the ether of space, and can act upon 

 each other at a distance. 



This may seem very complex and it may seem to be a complete over- 

 turning of the atomic theory of matter. In fact it is not in any sense 

 an overturning of any theory of matter. The chemist still deals with 

 atoms and combining ratios, and he will continue to do so. 



If a house builder should suddenly learn that the bricks which he 

 uses are not the final elements in his houses, it would in no way disturb 

 him. The fact that his bricks are composed of molecules, and these 

 molecules of atoms, and these atoms of negative and positive electricity, 

 would in no way change his professional practise in the design of houses. 

 The fact that we now find that every atom of any kind of matter is nor- 

 mally the abiding place of a certain definite number of negative elec- 

 trons, each having a mass of about the one thousandth of that of the 

 hydrogen atom, does not make these atoms behave differently from what 

 they did before. 



The fact that atoms of certain substances are exploding and giving 

 off energy is no more remarkable than the fact that nitroglycerin and 

 limestone behave differently. It is no more remarkable than the fact 

 that some houses fall to pieces and give off energy. And it is in no 

 way unexpected that an advance in our knowledge of matter has vastly 

 increased the complexity of our conceptions of its structure. The phe- 

 nomena around us with which we are in a certain sense familiar are by 

 no means simple. For example, let us assume that some stranger from 

 the regions which Dante described should now visit our earth, after an 

 absence of thousands of years. When he was here before he dwelt in a 

 cave. He sees our houses and he observes that empty houses attract 

 homeless families. He tries to explain how this attraction is to be 

 accounted for. He becomes acquainted with Newton's law of gravita- 

 tion and he at first thinks that this is the clue which he is seeking. He 

 soon learns that the size of the house has little to do with the attraction 



