Since the finding of the Water line as above described also determines the height, and hence the Cross-section of the dam required, the volume of the various materials entering into the construction of the dam is also at once found by adjusting the Planimeter to the Setting required by the given conditions and tracing the cross-section of the designed dam.

In fact, we could quite as easily cause the Instrument to give the estimated cost of the dam were it desirable to do so.

The Engineer who has made the above indicated calculations by any other method than by the aid of the Planimeter in the manner just described, will never again willingly revert to the old methods or believe that too much can be claimed for the value for the aid thus rendered by the new.

Obviously all that has been said as to the accuracy of the Instrument in the operations previously explained will apply with equal truth to that just described and need not be repeated.

In Table 12, under the heading of “Contents of Reservior,” is given the Settings, Constants, Vernier Units and other factors for all the scales commonly used in calculations of this nature. The derivation of these factors will be easily understood from the practical example we have used for illustration in the above explanation and from the general demonstration of the principle of the Planimeter given in Chap. III.

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