NEW CONCEPTIONS IN SCIENCE 



pith -balls, for instance. Under a convenient ar- 

 rangement, I can make this property pass, so it 

 appears, through a wire, and produce the same 

 effects at a considerable distance. What has hap- 

 pened ? 



There were two alternatives. The particles of 

 the glass rod might have been thrown into an es- 

 pecial form of motion, and this motion might pro- 

 duce attraction or repulsion, as it ran in one di- 

 rection or the other. Electricity, passing through 

 a wire, might in such a case be compared to a wave 

 that travels across a pond. On the other hand, 

 electricity might be a sort of fluid, a real sub- 

 stance, invisible, imponderable, subtle beyond any 

 other known force. 



Franklin's mind was of the concrete sort, and 

 the last explanation seemed to him to cover the 

 known facts in the most satisfactory way. His 

 conjecture was that all bodies are normally electri- 

 fied at all times. Under certain circumstances the 

 quantity of electricity contained in a given body 

 could be increased ; it would then display the prop- 

 erties of what is called positive electrification. If 

 the normal quantity of the fluid was decreased, 

 it would become negative. This subtle fluid must 

 possess a sort of inertia; it seems to flow from a 

 higher to a lower level, like water. Hence, for 

 example, the appearance of the electric spark. The 



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