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reason to expect the speedy restitution of electrical mate- 
riality. They require for their own views that electricity 
shall be nothing but force, nor must there be in their system 
of physics any matter of heat ; the forces of electricity and 
heat being, according to them, only phases of motion, a doc- 
trine which it devolves upon me to characterize as, according 
to my view, a transparent and absurd fallacy. I will do it as 
briefly as I can. 
“ Conservation of force ” has lately become “ conservation 
of energy,” it being too evident that force is subject to 
variations. Energy is now put forward in its place ; and its 
conservation dignified as the “ one great law of nature.” In 
laying a foundation for the doctrine of invariable energy, 
its partisans set out with asserting that force is lost if it 
produce no motion . It will be safer to state what I require to 
say, as much as possible in their own words ; after truly as- 
serting that “ in general, force is defined as that which pro- 
duces or tends to produce motion,” they add, “ now, if no 
motion be produced, the force which may have been exerted 
is absolutely lost.” Nothing can be more illogical than that 
conclusion ; for, by the definition, force may tend to 'produce 
motion without producing it ; and tending to produce motion 
has in physics no signification whatever, unless it means 
acting with a tendency to produce motion in opposition to 
some more powerful reaction which is rendering the action of 
the force — not inoperative, but inadequate. Now, force in 
action cannot be said to be physically lost ; or all the static 
forces in the universe would be absolutely lost, although 
actually occupied in quietly resisting and balancing one 
another. How pregnant with importance is the import of a 
word ! Had not a mechanical meaning of the term tendency 
been substituted for the physical one, no one would have been 
so simple as to ask in their disdain, “ What becomes of the 
enormous force with which the earth continuously attracts 
a mountain, or that with which the sun attracts the earth ? ” 
They would have perceived that nothing becomes of it ; but 
that the force, in continuously attracting, continuously exists ; 
and consequently never becomes lost. Do not the questioners 
perceive that they are seeking for mechanical utilitarianism 
under the word worh ? “We do no work, however much we 
may fatigue ourselves, if we try to lift a ton from the ground. 
If we try to lift a hundredweight, we can raise it a few feet, 
and have then done work.” In physics effect is work ; and 
is there no worh done — no effect — when the static pressure of 
the ton is reduced by the lifting force to nineteeen hundred- 
weight ? Is the force which is capable of lifting the one 
