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CHAPTER IX.

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Quantities of Materials (Cont'd.)

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IV. Special Methods of Measurement of Quantities.

As already stated, those principles of the Polar
Planimeter which make the instrument of such great value in the various
forms of measurement already described are also such as to make the instrument
almost universal in its application to all forms of engineering computations.
In fact, there are very few of the calculations so constantly met with
in engineering practice in which the aid of which the Planimeter is capable
is not as efficient and valuable as in those selected for illustration.
The simple enumeration of these practical applications would extend the
limits of our discussion far beyond the allotted space and will not be
attempted, but a brief description is desirable of a few of the more important
of these in order to clearly explain the use of the factors given in the
tables for the operations in question.
When not definitely states the table to be used in any given case is
easily determined by the conditions of the given problem. In many cases
the selection of the table from which to take the factors for adjusting
the Planimeter is determined by the unit in which it is desired that the
results should be expressed. For example, in making the measurement for
the volume of contents of a reservoir if the result is desired in U. S.
gallons the setting would be taken for the given scale from Table
12, while if the result is to be expressed in cubic feet Table
9 would be used.

The tables in all cases are made very complete so that the accuracy
of results can be very readily checked, usually by other factors given
in the same table.