From personal experience, I can testify that
lightning travels in what may be called currents
of air, or drafts. Lightning and thunder are
visible and audible effects, which occur in crowds
of differing gaseous or aërial globules. They
are lights and sounds elicited by the crush of
globules. Lightning, it has been recorded, has
been known to go in a straight line a distance of
three miles, and a person was once killed by what
is called the "back stroke," at a distance of
twenty miles from the explosion. But this
expression—the back stroke—is, I submit, a
misleading metaphor, for we all know that there is
nothing in storms like the back stroke of an oar,
a hammer, sword, or arm. During the last three
or four years, the theory that lightning is an
effect of aërial friction has been gaining ground,
for we find Mrs. Somerville, in the edition of her
Physical Geography, published in 1862, saying:
"Electricity of each kind is probably elicited by
the friction of currents of air." The lines, forks,
zig-zags, sheets, or balls of lightning, mark, therefore,
the course or direction of the crushings,
rubbings, and squeezings in the crowds of
igniting and exploding globules. The "back
stroke" ought, therefore, to be sent with the
"electric fluid," "the charge," the "thunderbolt
of Jupiter," and the "hammer of Thor," into
the museum of scientific antiquities; which
contains "flogiston" and "the philosopher's stone."
Some seven years ago I was standing for shelter
from a storm of thunder and rain in a coach entry
near the Elysian Fields in Paris. The gate of
the entry was folded and fastened back, and the
wind blew very fiercely through it. Out of each
side of the entry were doors admitting to the
staircases of the houses. Other persons who sought
shelter along with myself got out of the strong
wind blowing through the coach entry as quickly
as possible, and remained inside the doors of
the houses. But I remained right in the middle
of the entry, sometimes at the street end and
sometimes at the court end, watching the clouds
and the lightning, and counting the seconds
between the flash and the report. The storm
seemed everywhere. I was in the midst of it,
and expected to have an opportunity of seeing a
tree struck by lightning, when I observed the
persons clustered on one of the door-steps
observing me and talking seriously. Presently
a young artisan stepped out and up to me, risking,
as he knew and was soon proved, his own
life to warn me, and explained that lightning
frequently passed through the coach entries of
Paris. We had scarcely both got inside a door
in the side of the entry, when an oblong square of
lightning, the shape of the entry, reduced greatly,
was borne by the wind swiftly through it. A
tree was shattered by that storm within fifty
yards of where I stood; but, as I escaped a
manifest danger, I have been consoled by this
reflection for the loss of the opportunity of
witnessing the thunder-stroke. Another experience
furnishes still more decisive proof of the fact
that the course of lightning is along the line
of globular crowding produced by drafts. On
the 20th May, 1859, a memorable thunder-storm
burst on Brighton, and destroyed Streeter's
windmill on the Dyke Road. The east and west
cliffs of Brighton are divided by a valley running
north and south, and along the northern end of
this valley runs the London Road. I then lived
in the tallest house of this road. The southerly
winds blew the clouds along this road, and where
the obstacles were, at the Lion mansion, at my
residence, and at Streeter's mill, the lightnings
were most notable. This was the line of the
crowding from the confining of the globules.
The drawing-room of the house in question has
two tall windows, and against the wall between
them I had placed my upright desk, and at this
desk I was standing writing, my attention being
occasionally distracted from my work by the
flashes of lightning, by the rattling peals of
thunder, and by seeing the road turned into a
river. Two ladies were also in the room, one
reading at the table, and the other sewing on the
sofa. It was then that a flash or ball of lightning
came down the chimney, grazed close by
my right shoulder, and leapt out at the top of the
window. For the sake of ventilation, the mouth
of the chimney was not stopped up, and this
window was drawn down from the top. The
ladies who saw the lightning issue from the
chimney, said it had then the form of the aperture
through which it came, and I who saw it
leave, observed it assume the form of the
aperture through which it went.

These personal observations of mine leave no
doubt in my mind that one of the things which
determine the course of lightning is the crowding,
cramming, squeezing, crushing, and rubbing
of the thick-packed and close jammed globules.
Poets are not philosophers, nor are they always
observers, but they are, when good poets, the
repeaters of philosophy and observation, the
melodious echoes of thought and insight; and in one
of his couplets I find Mr. Alfred Tennyson,
when describing the gathering of a thunder-storm,
using the word cramming:

Comes a vapour from the margin, blackening
   over heath and holt,
Cramming all the blast before it; in its breast a
   thunderbolt.

Now that we know that thunder has no bolt,
the word  "thunderbolt" is as disagreeable to the
mind as the word "cramming" is pleasing to it,
a fact which shows that truth is as important to
the pleasures of literature as to the satisfaction
of science. A quotation from one poet is apt
enough to suggest another. Shakespeare makes
King Lear say

  Yon sulphurous and thought-executing fires,
  'Vaunt couriers of oak-cleaving thunderbolts,
  Singe my white head! and then all shaking
      thunder,
  Strike flat the thick rotundity o' the world.

Knowing, as we do, that lightning leaves a
sulphureous smell behind it, and that it cleaves trees
and singes hair, and that thunder, by the power