ADDRESS. 11 
matter. Amongst all these fertile investigators it seems to me that 
Thomson stands pre-eminent, because it is principally through him that 
we are to-day in a better position for picturing the structure of an atom 
than was ever the case before. 
Even if I had the knowledge requisite for a complete exposition of 
these investigations, the limits of time would compel me to confine myself 
to those parts of the subject which bear on the constitution and origin of 
the elements. 
It has been shown, then, that the atom, previously supposed to be 
indivisible, really consists of a large number of component parts. By 
various convergent lines of experiment it has been proved that the 
simplest of all atoms, namely that of hydrogen, consists of about 800 
separate parts ; while the number of parts in the atom of the denser 
metals must be counted by tens of thousands. These separate parts of 
the atom have been called corpuscles or electrons, and may be described 
as particles of negative electricity. It is paradoxical, yet true, that the 
physicist knows more about these ultra-atomic corpuscles and can more 
easily count them than is the case with the atoms of which they form 
the parts. 
The corpuscles, being negatively electrified, repel one another just as 
the hairs on a person’s head mutually repel one another when combed 
with a vulcanite comb. The mechanism is as yet obscure whereby the 
mutual repulsion of the negative corpuscles is restrained from breaking 
up the atom, but a positive electrical charge, or something equivalent 
thereto, must exist in the atom, so as to prevent disruption. The 
existence in the atom of this community of negative corpuscles is certain, 
and we know further that they are moving with speeds which may be 
in some cases comparable to the velocity of light, namely, 200,000 miles 
a second. But the mechanism whereby they are held together in a group 
is hypothetical. 
It is only just a year ago that Thomson suggested, as representing the 
atom, a mechanical or electrical model whose properties could be accu- 
rately examined by mathematical methods. He would be the first to 
admit that his model is at most merely a crude representation of actuality, 
yet he has been able to show that such an atom must possess mechanical 
and electrical properties which simulate, with what Whetham describes 
as ‘almost Satanic exactness,’ some of the most obscure and yet most 
fundamental properties of the chemical elements. ‘Se non é vero, é ben 
trovato,’ and we are surely justified in believing that we have the clue 
which the alchemists sought in vain. 
Thomson’s atom consists of a globe homogeneously charged with positive 
electricity, inside which there are one or more thousands of corpuscles 
of negative electricity, revolving in regular orbits with great velocities. 
Since two electrical charges repel each other if they are of the same 
kind, and attract each other if they are of opposite kinds, the corpuscles 
mutually repel one another, but all are attracted by the positive electricity 
