Address of Sir William Thompson. 279 
elements, at present a mere mystery in science, Helmholtz’s 
exquisite theory of vortex-motion in an incompressible friction- 
less liquid has been suggested as a finger-post, pointing a 
way which may possibly lead to a full understanding of the 
modern doctrine regarding atoms. > t 
that article one other short passage, finely describing the pres- 
ent aspect of atomic theory :—“The existence of the chemical 
atom, already quite a complex little world, seems very probable ; 
and the description of the Lucretian atom is wonderfully ap- 
Plicable to it. We are not wholly without hope that the real 
Weight of each such atom may some day be known—not merely 
the relative weight of the several atoms, but the number ina 
siven volume of any material; that the form and motion of the 
parts of each atom and the distances by which they are sepa- 
rated may be calculated; that the motions by which they pro- 
duce heat, electricity, and light may be illustrated by exact 
seometrical diagrams; and that the fundamental properties of 
the intermediate and ‘possibly constituent medium may be ar- 
rived at. Then the motion of planets and music of the spheres 
will be neglected for a while in admiration of the maze in which 
€ tiny atoms run.” = 
liven before this was written some of the anticipated results 
had been partially attained. Loschmidt in Vienna had shown, 
and not much later Stoney independently in England showed, 
how to deduce from Clausius and Maxwell's kinetic theory of 
ity & superior limit to the Stes of — ina ake geen 
urable space. as unfortunately quite unaware | L 
Loschmidt and Stoney had done when I made | a similar esti- 
mate on the same foundation, and communicated it to Nature, 
M an article ‘On the size of atoms.’ But questions of person 
Priority, however interesting they may be to the gm ee 
_ +eerned, sink into insignificance in the prospect of any a 0. 
| Geeper insight into the secrets of nature. The triple coincidence 
_ of independent reasoning in this case is valuable as confirmation 
— of a conclusion violently contravening ideas and opinions 
Which had been almost universally held regarding the — 
_ Sons of the molecular structure of matter. Chemists and ot oe 
_‘aturalists had been in the habit of evading questions as to the 
