298 MODERN SCIENCE READER 



A flexible chain, set spinning, can stand up on end while 

 the motion continues. 



A jet of water at sufficient speed can be struck with a 

 hammer, and resists being cut with a sword. 



A spinning disk of paper becomes elastic like flexible 

 metal, and can act like a circular saw. Sir William White 

 tells me that in naval construction steel plates are cut by 

 a rapidly revolving disc of soft iron. 



A vortex-ring, ejected from an elliptical orifice, oscillates 

 about the stable circular form, as an india-rubber ring 

 would do; thus furnishing a beautiful example of kinetic 

 elasticity, and showing us clearly a fluid displaying some 

 of the properties of a solid. 



A still further example is Lord Kelvin's model of a 

 spring balance, made of nothing but rigid bodies in spin- 

 ning motion. See his Popular Lectures and Addresses, 

 vol. I, p. 239, being his "Address to Section A of the 

 British Association" in 1884 at Montreal. 



If the ether can be set spinning, therefore, we may have 

 some hope of making it imitate the properties of matter 

 or even of constructing matter by its aid. But how are we 

 to spin the ether? Matter alone seems to have no grip of 

 it. I have spun steel discs, a yard in diameter, 4,000 times 

 a minute, have sent light round and round between them, 

 and tested carefully for the slightest effect on the ether. 

 Not the slightest effect was perceptible. We cannot spin 

 ether mechanically. 



But we can vibrate it electrically; and every source of 

 radiation does that. An electrified body, in sufficiently 

 rapid vibration, is the only source of ether-waves that we 

 know; and if an electric charge is suddenly stopped, it 

 generates the pulses known as X-rays, as the result of the 

 collision. Not speed, but sudden change of speed, is the 

 necessary condition for generating-waves in the ether by 

 electricity. 



We can also, it is believed, infer some kind of rotary 

 motion in the ether ; though we have no such obvious means 



