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“white plague.” Nor is good pure water free. Sometimes it can not 
be obtained at a price, as some of us well know. New York City is just 
now completing an additional water system, this last system alone costing 
one hundred and eighty millions of dollars. 
I wish to direct your attention to a phase of conservation that re- 
ceives less consideration than is generally accorded the conservation of 
timber, food, and soil. I wish to consider our fuel supply, and its relation 
to civilization. 
I shall begin by defining the word energy as the capacity for doing 
work; that is, the capacity for exerting force through space. Anything that 
‘an do work has energy stored in it, the quantity of energy being measured 
by the amount of work the thing can do. For instance, a clock spring or 
a clock weight has energy which it expends as it runs the clock; a battery 
has chemical energy which it expends when it rings a bell or drives a 
motor; a head of water has ehergy which it expends when it drives a tur- 
bine; gasoline has energy which it gives out as it heats a kettle or drives 
a motor car; a chunk of coal has energy which it expends when it heats 
our home or produces the pressure to drive a steam engine. 
If we represent all the heat energy in the universe by the letter 
“h”, all the chemical energy by “c’, all the electrical energy by “e’, 
and so on, using a different symbol for each and every one of the many 
forms of energy, then we may express the law of the conservation of 
energy in the form of an equation—h+c+e+ all other kinds of energy—=a con- 
stant. 
This law expresses the fact that energy is indestructible. We can 
neither create it nor destroy it. What then do we mean when we say that 
we should conserve and save our energy? To answer the question we 
shall need to consider two other laws or principles of energy, known as 
the Principle of Transformation of energy, and the Principle of Dissipa- 
tion or Degradation of energy. 
By transformation of energy we mean the conversion of energy of 
one form into energy of some other form. For instance, the energy of 
the coal is transformed in the boiler into the heat and pressure energy of 
steam, the engine converts this into a mechanical energy of motion; this 
may be used to drive a dynamo which converts it into electric energy, 
this may be passed through a lamp and be converted into light energy or it 
may be used to drive a motor which converts it again into mechanical 
energy, and so on. There is known no kind of energy that man can not 
