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while being in a fluid condition possesses one of the* most prominent 

 properties of a solid. We are required to believe in a hypothetical 

 substance which refuses to be bound down by the ordinary laws of 

 matter. It looks suspiciously like a demand on bhnd Faith, which 

 we have more than once been told, is in Science, tlie one unpardon- 

 able sin. ^tlll 



They all do say we must believe in Ether, 

 And sure, they all are scientific men. 



So much for the nature of the Ether. With respect to the move- 

 ments in it, there are further wonders. As before stated, it is the 

 medium whereby light and heat are conveyed across the stellar dis- 

 tances. Light and radiant heat are now authoritatively declared to 

 be nothing but wave motions, or more correctly I ought to say wave 

 motions translated into consciousness. By one set of waves the 

 nerves of Common Sensation are affected, and we are conscious of 

 warmth ; by another the Optic nervous fibres only are acted upon, 

 and we are conscious of light. Between the two is a mere differ 

 ence of the rate of vibration. I have already said that the Ether 

 is essentially an unquiet sea ; it is continually in a tremor, or 

 shivering condition. This is produced in the first place by those 

 motions of the molecules of all material bodies to which reference 

 was made in the first part of this paper. Men asked how our 

 nerves could possibly be affected by the vibrations of the molecules 

 of a body millions of miles away ; how did their effect travel across 

 the intervening space ? A similar question had been asked with 

 regard to sound, but that was easily answered ; it was soon dis- 

 covered that air was necessary for its transmission, and that sound 

 could not travel across a vacuum. A few simple experiments 

 showed that air was not necessary to the transmission of light or 

 heat, and the Ether was invented chiefly to provide a medium by 

 which they might travel through space. As with sound then, we 

 get waves ; not aerial, but ethereal ; so minute that vibrations or 

 tremors describes them better. In talking of these we have to deal 

 with high numbers. It is doubtless known to you that when the 

 middle C of a pianoforte is sounded, the string vibrates 256 times a 

 second ; the next C above, 512 times, the next, 1025. If the 

 instrument have seven octaves, the lowest note being C, the upper- 

 most note would by caused by 4096 vibrations per second. These 

 may seem very high rates of rapidity, but they quite fade away into 

 nothingness when we come to ethereal vibrations which produce 

 the sensation of light. The lowest number which can affect the 

 optic nerves is 458 billions per second. Once more I ask you not 

 to let this vague number slip by unregarded, but to dwell upon it 

 for a muiute for two. Try to conceive of 458 millions of millions 



