NEW CONCEPTIONS IN SCIENCE 



possibility in the fact that negative and positive 

 electricity seem to move at different speeds. The 

 chief difficulty would lie in the fact that space is 

 simply teeming with meteors and meteoric stones; 

 the earth sweeps up a hundred or two hundred 

 tons of them a day. They might make a voyage 

 round the moon rather perilous. 



As the space-filling ether is purely an inference, 

 it is hard to get any precise ideas of its nature 

 or its qualities. For the present it is simply a 

 working hypothesis that may have its day. In- 

 deed, in its full development, it is a collection of 

 suppositions that war most unkindly one with the 

 other. Nevertheless, the ether may be a fact, what- 

 ever be the fate of present imaginings about its 

 properties. If space be filled with a uniform ma- 

 terial, like air, then waves or vibrations set up 

 would travel always at the same rate of speed, just 

 as sound travels always at the same rate in air 

 of uniform density. That is exactly what seems to 

 occur. Light appears to be a form of wave-mo- 

 tion, and so does radiant heat, and likewise the 

 form of energy discovered by Hertz, and so mar- 

 vellously employed by Marconi, which we call elec- 

 tric-waves. Light -waves range in length from 

 60,000 to 30,000 to the inch; heat-waves from this 

 to only about 350 to the inch; electric- waves may 

 vary from a few tenths of an inch to a thousand 



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