nds a place in many treatises on atmospheric phenomena.
A gas of any kind would disperse itself in the air; it could not dance
about as these lights are said to do, and there is no chemical means
known whereby it could be produced in sufficient purity and quantity
from the earth to produce the effects which are described.[3]

[Footnote 3: The present writer has made an extended and careful study
of marsh and swamp phenomena, and is very familiar with the aspect of
these fields in the nighttime. He has never been able to see any sign of
the Jack-o'-lantern light. Looking fixedly into any darkness, such as is
afforded by the depths of a wood, the eye is apt to imagine the
appearance of faint lights. Those who have had to do with outpost duty
in an army know how the anxious sentry, particularly if he is new to the
soldier's trade, will often imagine that he sees lights before him.
Sometimes the pickets will be so convinced of the fact that they see
lights that they will fire upon the fiction of the imaginations. These
facts make it seem probable that the Jack-o'-lantern and his companion,
the Will-o'-the-wisp, are stories of the overcredulous.]

In the upper air, or perhaps even beyond the limits of the field
which deserves the name, in the regions extending from the poles to
near the tropics, there occur electric glowings commonly known as the
aurora borealis. This phenomenon occurs in both hemispheres. These
illuminations, though in some way akin to those of lightning, and
though doubtless due to some form of electrical action, are peculiar
in that they are often attended by glows as if from clouds, and by
pulsations which indicate movements not at electric speed. As yet but
little is known as to the precise nature of these curious storms. It
has been claimed, however, that they are related to the sun spots;
those periods when the solar spots are plenty, at intervals of about
eleven years, are the times of auroral discharges. Still further, it
seems probable that the magnetic currents of the earth, that circling
energy which encompasses the sphere, moving round in a general way
parallel to the equator, are intensified during these illuminations of
the circumpolar skies.

GEOLOGICAL WORK OF WATER.

We turn now to the geological work which is performed by falling
water. Where the rain or snow returns from the clouds to the sea, the
energy of position given to the water by its elevation above the ea