ring in any underground workings as a very favourable
augury for the close approach of highly mineralised lodes. If, then,
moisture be favourable, first to the presence of mineral-bearing
country and secondly to the conductivity of electrical lines, it is
obvious that there is a hopeful field for the exercise of ingenuity in
bringing the one into a practical relation to the other.

The occult scientific reasons for the connection may not be
understood; but it is sufficient for practical purposes to know that,
in a certain line from the surface outcropping of a mineral lode,
there has been given a demonstration of less electrical resistance
along that line than is experienced in any other direction; also to
know that such a line of least resistance is proved to have been, in
almost innumerable instances, coincident with the best line of
mineral-bearing country. The case is similar to that of the rotation
of crops in its relation to scientific microbiology. The art of mining
may get ahead of the science of physiography in respect of
earth-currents and lines of least resistance, as showing where mineral
lodes may be expected. Yet there is no doubt whatever that science
will not in the one case lag so far behind as it has done in the
other.

The first notable service rendered by systems of the kind indicated
will no doubt be in connection with the rediscovery of very valuable
lodes which have been followed up for certain distances and then lost.
In an instance of this description much fruitless exploration drives,
winzes and "jump-ups" may have been carried out in the surrounding
country rock near the place where the lode last "cut out"; but, in the
absence of anything to guide the mine manager and surveyor as to the
direction which the search should take, nothing but loss has been
involved in the quest. Several properties in the same neighbourhood
have, perhaps, been abandoned or suspended in operation owing to very
similar causes.

The whole group may perhaps have then been bought by an exploration
company whose _modus operandi_ will be as follows: The terminal of the
electrical exploration plant is fixed at the end of the lode where it
gave out, or else immersed in the water of the shaft which is in
connection with the lode system; and another similar terminal is fixed
by turns in each shaft of the contiguous group. The electrical
resistances offered to the return currents, or to the wireless
vibrations, are then car