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prospect of accounting for all we see around us by any such 
process as this. I see evidence of the operation of will and 
design, which cannot be eliminated even if we would wish to 
eliminate it ; and that which we are obliged to admit as 
having operated in the past may yet operate in the future, may 
be operating in the present. 
I have said that the principles of the conservation of force 
and of the dissipation of energy lead to the conclusion that 
the present order of things is leading towards a goal of 
universal death. Of course, this is only on condition that 
everything beyond the operation of the ordinary natural laws 
such as we can investigate is excluded. It becomes a curious 
question, is there any process which we can even picture to 
our minds, by which, without any violation of the principle of 
the conservation of energy, we can conceive the distribution 
of energy so altered as to make it again available for useful 
purposes, instead of having everything in a condition of dead 
uniformity ? The only satisfactory affirmative answer that I 
am acquainted with to this question is contained in a sug- 
gestion made by the late Professor Clerk Maxwell. 
Let us imagine a closed vessel, the sides of which we will 
for simplicity’s sake suppose impervious to heat, filled with a 
gas in a uniform condition, and consequently at a constant 
temperature throughout. In the first place, what must we 
picture to ourselves as the state of things within the vessel ? 
How must we think of the gas itself ? The laws of chemical 
combination, embraced as they are in the atomic theory of 
Dalton, give us strong ground for supposing that a mass of 
ponderable matter is not a continuous plenum, but consists of 
ultimate molecules alike to one another in matter of the same 
kind. The laws of crystallography again seem hard to account 
for if we refuse to admit the supposition of ultimate minute 
molecules. If these exist, a gas like a solid of liquid must be 
thought of as a congeries of molecules. But what conception 
are we to form of it in relation to heat ? What is the physical 
picture of a higher or lower temperature as measured by the 
thermometer ? There is the strongest reason now to believe 
that heat is in fact a mode of motion ; that radiant heat consists 
in a vibratory movement of that medium pervading space, at 
least to the distance of the furthest visible star, which we 
call the luminiferous ether, and whose existence we are obliged 
to assume in order to account for, as most marvellously well 
it does account for, the phenomena of light. When radiant 
heat is absorbed by ponderable matter, we have reason to 
believe that it is that the energy of the vibratory movement 
of the ether is transferred to the ponderable matter, of which 
