12, that is to say, the specific conductivity of river-water is
1:91120000. Calculation, then, gives as the resistance of the earth in
Siemens units:
Calculated. Observed.
Square plate. 33.5 33.5
Annular ring. 31.76 32.5
These figures prove the accuracy of the calculations that had been
made in an approximate way.
The experiments were performed upon the Elba, above Dresden. Other
experiments still had reference to the influence of immersion. In
order to diminish polarization, only instantaneous currents from the
measuring pile were employed. It was to be supposed that the current
of water through which the bubbles of gas were removed from the
electrodes would not have permitted of a notable resistance of
polarization. Later measurements, made upon a ribbon buried, like the
plates, in the earth, gave likewise most favorable results.
As a result of these experiments, the State railways of Saxony have,
in such cases as were practicable, introduced the annular network of
copper. There are some manufacturers, too, who seem desirous of
adopting this system, although it has hardly emerged from the period
of experiment. The pecuniary advantages that will result from an
application of it ought, it would seem, to dispel a large proportion
of the criticisms directed against the erection of lightning rods,
from the standpoint of expense, and contribute to extend an
arrangement which may be considered as a very happy one.
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