It has been incontrovertibly established by the experiments of modern
philosophers, that the phœnomena of electricity are identical with those
of thunder and lightning. The human body is alike affected by both; and
death, whether it be occasioned by the discharge of an electrical
battery, or by that of a thunder cloud, exhibits effects precisely
analogous.
Mr. _Hunter_ supposed that when death is thus occasioned, there is an
instantaneous and entire annihilation of the vital principle, in every
part of the animal machine; and that the muscles are therefore relaxed,
and incapable of contraction, that the limbs do not stiffen[54], as in
other cases of death, nor the blood coagulate, and that the body very
speedily runs into a state of putrefaction. The experiments however of
Mr. _Brodie_[55] will induce us to pause, and institute farther
enquiries before we receive this theory as unexceptionable. It will
appear that in the following experiments of this physiologist, an
instantaneous extinction of vitality did not take place, but, on the
contrary, the functions of the brain were those on which the electric
shock exercised its primary influence. An electric battery of six jars
having been charged with electricity, the shock was made to pass through
a Guinea pig, in the longitudinal direction from the head to the tail:
the animal immediately fell on one side, insensible, as if stunned; a
convulsive action of the muscles of the extremities was observed, but
did not long continue; and the function of respiration was not
interrupted. In a few minutes sensibility was restored, and the animal
recovered. A shock from a battery of nine jars was then passed in the
same manner through another Guinea pig; the animal immediately fell on
its side, exhibited a convulsive action of the voluntary muscles of the
limbs, but uttered no cries, and although attentively watched, no signs
of respiration could be discovered after the shock had passed through
it. Three minutes afterwards, Mr. _Brodie_ opened the chest, and found
the heart acting with regularity and vigour, about 80 times in a minute,
and circulating dark coloured venous blood; the peristaltic motion of
the intestines was likewise visible; and the muscles, when made the part
of a galvanic circuit, readily contracted. In this experiment, observes
Mr. _Brodie_, it is evident that the electric shock did not destroy the
irritability of the muscular fibre, nor did it affect the action of the
heart. _Death took place precisely in the same manner as from a severe
injury of the head_; and the animal died, manifestly from the
destruction of the functions of the brain; and, in this case, Mr.
_Brodie_ has no doubt, but that if the lungs had been artificially
inflated, the action of the heart might have been maintained, and the
animal probably have been restored to life.
The nature and extent of the injury inflicted by lightning, depend upon
the intensity and direction of the electrical discharge, and vary
greatly in degree; by far the greater number of flashes are harmless
discharges from one cloud to another, and the instances in which it
strikes the earth are comparatively rare: when however this does occur,
and it directs its course through a human being, it may expend its
influence upon the surface, and produce partial or general
vesications.[56] Sometimes the clothes of the person have been violently
rent, and the metallic substances about them melted; or it may pass
through the body, without including the clothes, and it may occasion
death without injuring the organic structure of any part of the body: or
it may pass through only a particular portion of the body, and produce
local injury.
But it has happened that persons have been struck when the tempest has
appeared to be at a considerable distance; this has been explained by
Signor _Beccaria_, by supposing that it is a discharge of electric fluid
from the earth, occasioned by the passing of a cloud that has just
before, in the elemental strife, been rendered negatively electric. Lord
_Stanhope_ distinguishes such a discharge by the name of the _Returning
Stroke_.[57]
As a provision for personal security during a thunder storm, a few
precautions are necessary, and we are induced to notice them in this
place, as their history is necessarily involved in our enquiries
concerning death by lightning. In the open air, shelter ought not to be
sought immediately under trees, for should they be struck, such a
situation would be attended with the most imminent peril: on the
contrary, the distance of twenty or thirty feet from such objects, may
be considered as affording a place of safety, for should a discharge
take place, they will most likely receive it, and the less elevated
bodies will escape. Any surface of water, and even the streamlets that
may have resulted from a recent shower should be avoided, for being
excellent conductors, the height of a man, when connected with them, is
very likely to determine the course of an electrical discharge. The
partial conductors, through which the lightning directs its course when
it enters a building, are usually the appendages of the walls and
partitions; the most secure situation is therefore the middle of the
room, and this situation may be rendered still more secure by lying on a
hair mattress, or even on a thick woollen hearth rug. The part of every
building least likely to receive injury is the middle story, as the
lightning does not always pass from the clouds to the earth, but is
occasionally discharged from the earth to the clouds, as in the case of
the “_returning stroke_;” hence it is absurd to take refuge in a cellar,
as recommended by Dr. _Priestley_; indeed many instances are on record,
in which the basement story has been the only part of a building that
has sustained severe injury, the electric charge being divided and
weakened as it ascended. Any approach to a fire-place should be
particularly avoided, for the chimneys are very likely to determine the
course of the lightning; the same caution is necessary with respect to
gilt furniture, bell-wires, and moderately extensive surfaces of metal
of every description.