266 THE GRAMMAR OF SCIENCE 



come in their way, and, furthermore, their relative motion 

 is easily seen to closely depend upon their relative position. 

 Now we see smoke-rings because the moist particles in 

 the smoke render the gaseous mixture visible, as similar 

 particles render steam visible ; but we might blow air- 

 rings in air, which would act precisely as the smoke-rings 

 do, only they would be invisible. Such rings are termed 

 vortex-rings ; and if we study the action of such rings 

 not in air or water but in our conceptual perfect fluid, 

 we shall find that, like atoms, they retain their own 

 individuality ; they enter into combination, but cannot 

 be created or destroyed. This is the basis of Lord 

 Kelvin's vortex- ring theory of matter — ^a prime atom, 

 according to his theory, is an ether vortex-ring.^ By the 

 aid of vortex-motion, or spinning elements of liquid in a 

 liquid, we are also able to conceive a liquid stiffened up 

 to a required degree of resistance to sliding strain, and 

 thus to replace the ether as a perfect jelly by the ether as 

 a perfect fluid in a turbulent condition.^ This is the so- 

 called gyrostatic ether, the properties of which have been 

 developed by Dr. J. Larmor. We can then dispense with 

 Sir George Stokes' hypothesis of slight viscosity. But 

 however suggestive these ideas may be for the lines upon 

 which we may in future work out our conceptions of ether 

 and atom, they are very far indeed from being at present 

 worked out, and there are many difficulties in the vortex- 

 atom theory — notably that of deducing gravitation — 

 which the present writer is not very hopeful will ever be 

 surmounted. 



While Lord Kelvin's theory supposes that the sub- 

 stratum of an atom always consists of the same elements 

 of moving ether, the author has ventured to put forward 

 a theory in which, while the ether is still looked upon as 

 a perfect fluid, the individual atom does not always 



1 For a fuller account of this theory see Clerk-Maxwell's article " Atom " 

 in the Encyclopcrdia Bi-itantiica, or his Scientific Papers, vol. ii. pp. 445-84. 

 vSee also as to spin producing elastic resistance Sir William Thomson's Popular 

 Lectures and Addresses, vol. i. pp. 142-46 and 235-52. 



2 See G. F. Fitzgerald: "On an Electro -magnetic Interpretation of 

 Turbulent Fluid Motion," Nature, vol. xl. pp. 32-4. 



