61 
epoch, of the f consistentior status' was probably between 
these dates/' (N. P. pp. 712-716). 
We read also in The Unseen Universe as follows, p. 91 • 
“ Heat is the communist of our universe, and will no doubt 
bring the system to an end. The sun is the furnace, or source 
of high-temperature heat to our system, as the stars to other 
systems. The energy essential to our existence is derived 
from the heat the sun radiates, and represents a very small 
part of it. But while the sun supplies us with energy, he 
himself is getting colder, and must ultimately, by radiation 
into space, part with the life-sustaining power he now possesses. 
In each case of collision, there will be the conversion of visible 
energy into heat and a partial and temporary restoration of 
the power of the sun. At length, however, the process will 
have come to an end, and he will be extinguished ; until, after 
long ages, his black mass is brought into contact with that of 
his nearest neighbour." 
The idea is then pursued further, as follows : — 
“After unimaginable ages these two stars, the Sun and 
Sirius, having each long since devoured his attendants, and 
exhausted their heat energy by radiation into space, may be 
imagined travelling towards each other with accelerated motion. 
1 hey will at last approach each other with great velocity, and 
finally form one system. The two will rush together and form 
one mass, the orbital energy being converted into heat, and 
the matter probably evaporated and changed into a gaseous, 
nebulous condition. Ages pass away, and the large double 
mass ultimately shares the same fate that long since overtook 
the single masses that compose it. It gives out its light and 
heat into space, and becomes dark, until it comes to form one 
of the constituents of a still more stupendous collision. By 
a piocess of this kind the primordial potential energy is 
gradually converted into light and heat, and then ultimately 
dissipated into space." 
Such is the doctrine of the Dissipation of Energy, as held 
by the three eminent physicists and mathematicians, Professors 
Sir W . Thomson, Tait, and Balfour Stewart. Mr. Spencer, 
again, has seven chapters on the kindred subject of Evolution, 
and defines it in these words : — “ A change from incoherent 
homogeneity to coherent heterogeneity, accompanying the dis- 
sipation of motion, and the integration of matter." This is 
plainly, in abstract terms, the same process just described, 
by which suns, with their planets, are formed out of nebula, 
hen the planets fall into the suns, and the suns in long succes- 
sion into each other. A strange inversion of the natural 
* 
