s no moist return circuit. Deflections
of the compass, due to the passing of earth-currents along the natural
lines of conductivity in the soil or the rocks, are so frequently
noticed as to be a source of calculation to the scientific surveyor
and astronomer. It can thus be shown not only that definite lines of
least electrical resistance exist in the earth, but also that natural
currents of greater or less strength are almost constantly passing
along these lines.

Some of the curious and puzzling empirical rules gained from the
life-long experience of miners in regard to the varying richness and
poorness of mineral lodes, according to the directions in which they
strike--whether north, south, east or west--may very probably be
explained, and to some extent justified, by the fuller light which
science may throw upon the conditions determining the action of
earth-currents in producing results similar to those of electro
deposition. If, in a given region of a mineral-bearing country, the
geological formation is such as to lend itself to the easy conduction
of currents in one direction rather than in another, the phenomenon
referred to may perhaps be partially explained. But, on the other
hand, the origin of the generating force which sets the currents in
motion must first be studied before the true conditions determining
their direction can be understood. In other words, much that is now
obscure, including the true origin of the earth's magnetism, must be
to some extent cleared up before the reasons for the seemingly erratic
strike of earth-currents and of richness in mineral lodes can be fully
explained.

Practice, however, may here get some distance ahead of science, and
may indeed lend some assistance to the latter by providing empirical
data upon which it may proceed. When once it is clearly seen that by
delicate electrical instruments, such as the telephone, the microphone
and the coherer as used in wireless telegraphy, the line of least
resistance on any given area of the earth's surface or any given piece
of its crust may be determined, the bearing of that fact in showing
the best lines of moisture and therefore the likeliest lines for
mineral lodes will soon be recognised in a very practical manner.

No class of men is keener or more enterprising in its applications of
the latest practical science to the getting of money than mining
speculators. Nor have they at all missed the significance of moist
bands occur