CHAPTER V 
ELEMENTS WHICH REDUCE VALUE 
Deductions from Value 
The Lessening of Worth. — The value of a property may in- 
crease or decrease with age. Having in the preceding chapter 
called attention to the essentials of value and to certain elements 
which add value, there will be considered briefly in this chapter 
some of the factors which reduce value. 
In the case of any operating plant there will be parts which 
deteriorate or wear out under the effect of continued use. By 
ordinary care the rate at which the perishable parts of a plant 
are consumed in rendering useful service is held at or near the 
average rate which experience teaches should be regarded as 
inevitable. If ordinary care is not exercised and a plant by 
reason of neglect gets into a condition which requires special 
attention to restore it to an average condition, all circumstances 
of use and age being considered, the prospective outlay to ac- 
complish this rehabilitation is called deferred maintenance. But 
even when there is no deferred maintenance there may have 
been a lessening of worth due to the fact that on account of 
wear and tear, or by reason of obsolescence, or inadequacy, 
or from any other cause, the time of probable serviceability of 
any article in question is being continually lessened. Loss of 
value from such cause is depreciation. Or again, if cost is made 
a starting point, it may be found that there is included unused 
property perhaps held to meet a future demand, but which, 
when valuations as a basis for rates are under consideration, 
may have to be omitted or deducted from the aggregate of the 
listed properties. And, finally, the property under considera- 
tion may include items designed of a capacity to meet future 
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