A HISTORY OF SCIENCE 



Meantime, however, the ether, be it substance or be 

 it only dream-stuff, is serving an admirable purpose in 

 furnishing a fulcrum for modern physics. Not alone 

 to the student of energy has it proved invaluable, but to 

 the student of matter itself as well. Out of its hypo- 

 thetical mistiness has been reared the most tenable 

 theory of the constitution of ponderable matter which 

 has yet been suggested or, at any rate, the one that 

 will stand as the definitive nineteenth-century guess at 

 this ' ' riddle of the ages." I mean, of course, the vortex 

 theory of atoms that profound and fascinating doc- 

 trine which suggests that matter, in all its multiform 

 phases, is neither more nor less than ether in motion. 



The author of this wonderful conception is Lord Kel- 

 vin. The idea was born in his mind of a happy union 

 of mathematical calculations with concrete experi- 

 ments. The mathematical calculations were largely 

 the work of Hermann von Helmholtz, who, about the 

 year 1858, had undertaken to solve some unique prob- 

 lems in vortex motions. Helmholtz found that a vor- 

 tex whirl, once established in a frictionless medium, 

 must go on, theoretically, unchanged forever. In a 

 limited medium such a whirl may be V-shaped, with 

 its ends at the surface of the medium. We may imi- 

 tate such a vortex by drawing the bowl of a spoon 

 quickly through a cup of water. But in a limitless 

 medium the vortex whirl must always be a closed ring, 

 which may take the simple form of a hoop or circle, or 

 which may be indefinitely contorted, looped, or, so to 

 speak, knotted. Whether simple or contorted, this 

 endless chain of whirling matter (the particles revolv- 

 ing about the axis of the loop as the particles of a string 



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