LIV PHILOSOPHICAL SOCIETY OF WASHINGTON. 
greater ingenuity and method of the metaphysic art with which 
it is conceived ? 7 
If within the limits of this discussion I had the time, and if, 
under the limitations of my knowledge, I had the ability, to carry 
this enquiry into the realm of molecular physics and dynamics, 
where such star-eyed mystagogues as a Clausius or a Rankine, a 
Clerk-Maxwell or a Sir William Thompson have borne the thyrsus 
of science before us, it would be easy to show that, under their guid- 
ance, we have escaped the pitiless parallel lines of the Epicurean 
atoms only to find ourselves inextricably implicated in the knotted- 
ness and linkedness of the vortex rings of atoms as they execute 
their infinite evolutions and invyolutions, vibrating now in one period 
and now in another behind that vail of matter where they can be 
descried only by the shadowy lines they reveal to the spectroscopic 
imagination. “It is the mode of motion,” says Clerk-Maxwell, 
“which constitutes the vortex rings, and which furnishes us with 
examples of that permanence and continuity of existence which we 
are accustomed to attribute to matter itself. The primitive fluid, 
the only true matter, entirely eludes our perceptions when it is not 
endued with the mode of motion which converts certain portions of 
it into vortex rings, and thus renders it molecular.” * 
Of these vortex rings we must say, in the dialect of the schools, 
cognoscendo ignorantur, sed ignorando cognoscuntur. Withheld from 
positive conception, yet necessitated to scientific thought and spec- 
ulation by the exigencies of the knowledge we can conceive posi- 
tively, they afford a good illustration of the physical metaphysic 
which has wafted the scientific mind of the present generation into 
an empyrean as much higher than the empyrean of Plato as the 
spectroscopic vision of modern science is more far-reaching than the 
highest flight of metaphysic wit among all the physical atomizers 
who ever lived or dreamed in Greece. Every chemical atom, says 
Sir John Herschel, is forever solving differential equations, which, 
if written out in full, might belt the earth. ‘An atom of pure 
iron,” says Jevons, “is probably a vastly more complicated system 
than that of the planets and their satellites.” 
Between metaphysical physics and physical metaphysics there is 
a world-wide difference. The invisible ether posited behind the 
* Encyclopedia Britannica, sub voce ‘‘Atom.”’ 
