The morning star and Catholic messenger., 1878-12-01
LIGHTNING CONDUCTORS.

Daring thunderstorm we may nouce
that buildings having a rod of metal des-
cending from their highest point into the
earth, called "lightniDg conductors" are
not injured by the storm. Can we explain
the reason of this. We have seen by our
experiments that electricity passes away
from q conductor il it is connected by a
metal chain with the earth, but not if it
is connected by glass. Let us now work
our machine till we get spark when we
bring our finger near it. If we now take
metal rod in our hand, and hold it close to
our finger, 30 that it's end comedies with
the point of the finger, and bring both near
the prime conductor of our machine. we
shall find we cannot now get spark to
touch the finger; it will invariably pass
to the metal rod, and if the rod be long
enough to reach the ground, the e'ectlici-
ty will not pass through our body at all,
but pass straight to the earth by the metal
rod. If, however, instead of metal rod
we take glass one, ard use it In the same
way, the result will be very different. Now
we shall not be able to get epaIk to
touch the glass at all it will invariably
strike the finger, and pass through our
body to the ground. If, therefore, we
have a metal rod standing fixed in the
ground beside us during thunder storm
a fiaeh of lightning coming, would, like
the spark from the conductor, pick out
the METAL rod and pass by it harmlessiy to
the ground, leaving us untouched. Oo
| the other hard, were a glass rod beside US,
the lightning would leave the glass rod
untouched, and pass through our bodies
| to the ground, most likely oepriving Us OF
| life in the passage. This Is the whole
principle of lightning conductors. We ez
prees it by saying that electricity aiways
passes by the best conductors. Knowing,
| as we do, that metals are better conduct
ors than stone, wood, etc., of which ouI
buildings are composed, we protect them
| I'D ol ,F1nnk kaH IFh
| the ground to their highest point. 1t it
found by experience that rod erected in
| this way protects space all around it
equal to twice its height. Thus q rod
| so feet high protects q space of 100 feet on
every side of it. From the knowledge OF
the principals of lightning conductors, we
may know the positions of safety. The
French parGgreIes are also other forms OF
! lightning rods. They are em I'll conductors
| set up by means of poles in the vineyards
| in France, TO draw off the electricity from
| the atmosphere ever them, and thus pre-
vent the accumulatiops which, when they
| occurred, were found to generate hail
| storms. Arago proposed that these conduct
| ors should be raised and supported by email
| batteries connected by means Of slender
wires or chains with the ground. This plan,
| like some other ingenious applications OF
electricity, was found to act perfectly wefl
| in theory, but proved impracticable, owing
| to the great expense of setting up and
maintaining such q system over any great
extent of country. Cases have been known
| ia which a gold pin in girls hair has been
| fused by lightning, OF a bracelet melted off
| lady's wrist, without the wearer'S suffer
ing any actual injury. Sportsmen, owing
to the iron of their weapons, are apt to be
struck by lightning. Hence, some philos-
opher-half in jest, half in earnest-has
proposed that a portable lightning rod in
connection with an umbrella should be
provided for people liable to be caught in
thunder storms. Such q pGrGpLuie, if the
ferrule were provided with pointed me-
talic rod projecting into the air, and con-
nected with detachable chain or wire to
drag on the ground behind, could bring the
bearer and his paraphernalia Of destruction
safely through the electric tempest, even
though the lightning should play all round
him. We must keep away from the
neighborhood of bad or non-conductoTs,
and near to good ones, if they are connect
ed with the ground, A man clad in the
steel armour cf the Middle Ages would be
almost perfectly safe, especially if he had
steel points on his boots to stick into the
ground, as he would have a capital conduc-
tor all around him. For the came reason,
a man in an iron bed will be safe, espec'
nlIv if the bed be connected by metal to the
gas pipe, so as to make complete contact
With the earth. Standing near high body