one weak point, which they possess in common with the plate, and that
is, their dimensions cannot be easily adapted to the nature of the
ground met with without a notable increase in the expense. Now, if the
ground should offer a conductivity less than what was anticipated, and
it were desired to increase the plate, say by one-third, it would be
impossible to do so as a consequence of the closed form.

One important advantage is realized in this respect by combining the
ring and the network in the form of a reticulated ring having a
diameter of from 1 to 1½ meters. On cutting this ring at a given place
and according to a certain radius we obtain the reticulated ribbon
shown in the accompanying figure. The thickness of the wires is 2.5
mm., and their weight is 0.475 kilo. per meter. L, L, and L are the
points at which the conducting cable is soldered. A reticulated ribbon
of copper can be made in advance of any length whatever, and,
according to local exigencies, it may be easily curved and given the
form of a flat or cylindrical ring of varying width. Even though the
ribbon has already been cut for a ring of given diameter, it may be
still further enlarged by drawing it out and leaving a bit of the ring
open, so as to thus obtain a nearly corresponding diminution in the
resistance. Such a resistance may be still further diminished by
rendering the ring higher, that is to say, by employing an annular
cylindrical form.

After assuring himself, by experiments on a small scale, that
calculation and observation gave concordant results for the flat ring,
the author made an experiment on a larger scale with the annular
network. For practical reasons he employed for this purpose a copper
wire 2.5 mm. in diameter, which may be expected to last as long as one
of iron plate 2 mm. in thickness. Calculation showed that in a ribbon