168 PROGRESS OF SCIENCE IN THE CENTURY. 



But " a common vortex ring of air or water con- 

 tains within itself the seeds of its own decease; it 

 is composed of an imperfect fluid, possessing that is 

 to say viscosity, and accordingly its life is short ; its 

 peculiar energy being dissipated, its vortex motion 

 declines, and as a ring it perishes. But imagine 

 a ring built of some perfect fluid, of some medium 

 devoid of viscosity, as the ether is; then it may be 

 immortal; it can neither be produced nor annihi- 

 lated by known means ; and it is just this property, 

 combined with other properties of elasticity, 

 rigidity, and the like, that led Lord Kelvin origi- 

 nally to his brilliant and well-known hypothesis." 



Thus if the universe be filled with ether, and if 

 that universal medium be a perfect fluid, " then, if 

 any portions of it have vortex-motion communicated 

 to them, they will remain forever stamped with that 

 vortex-motion; they cannot part with it; it will re- 

 main with them as a characteristic forever, or at 

 least until the creative act which produces it shall 

 take it away again. Thus this property of rotation 

 may be the basis of all that appeals to our senses as 

 matter" f 



The Atomic View of Nature. Opinions differ as 

 to the fittest way in which to express the facts known 

 in regard to matter, but even those who believe, for 

 instance, that " all matter is resolvable into an ag- 

 gregate of electric charges of opposite sign," will 

 admit their acceptance of the atomic view of nature, 

 though all may not agree verbally with Prof. Oliver 

 Lodge when he says " a lump of matter is as surely 

 composed of atoms as a house is built of bricks." 



* Prof. Oliver Lodge. Modern Views of Matter. The Inter- 

 national Monthly, I. (1900), p. 501. 

 t Prof. Tait's Recent Advances, 1876, p. 294. 



