The Sun.
London, England, 1822-09-18 00:00:00

ELECTRICAL EXPERIMENT.

[From the Plymouth Telegraph.]
We last week noticed an invention by a.gen-
tleman of Plymouth for conveying the electric fluid, by means
of a copper conductor fixed in the masts, through the bottoms
of ships. Instead of being ascribed to Mr. T. Harris, jun. as
then stated, it should have been Mr. W. S. Harris. The ex-
periment has taken place in the harbour, and completely suc-
ceeded, as will be seen from the following details.
It is not necessary to quote the numerous instances of the
tardy attention bestowed upon many important results ob-
tained from natural and experimental philosophy ; but it may
now he sufficient to remark that seventy years have elapsed
since Dr. Franklin demonstrated the efficacy of metallic con-
ductors in protecting buildings from the destructive effects
of lightning. Although the application of conductors on
land is generally judicious, and their advantages are admit-
ted, yet, on shipboard, where the effects of lightning are
most to be dreaded, from the inflammability of the materials of
which the ship and stores are usually composed, the introduc-
tion of electrical conductors has been lamentably neglected, or
injudiciously employed. This indeed may in some measure be
traced to the difficulty of placing any fixed or continuous con-
ductor ill a situation so liable to change and motion as the mast
and rigging of a ship ; and consequently the only species of
conductor that has been adopted,, is a chain, or long links of
wire, one end of which is designed to be hoisted to the
mast head, whilst the other passes over the side of the ship,
and communicates with the water ; but independent of its
defective construction, from its small dimensions, the in-
convenience of being constantly hoisted, and its consequent
liability to be injured, are very obvious. This species of
conductor is therefore usually kept packed in a case, and only
hoisted on the approach of danger, which it may then be
too late fully to avert. To remedy these inconveniences Mr.
Harris proposed to -place in the back of the masts a slip of cop-
per, which is to be continued to the interior or hole of the cap
of each mast; consequently, coming into contact with the mast
above, the continuity will be preserved, without preventing the
upper masts being lowered. The conductors of the lower masts
are in be continued to the keel, and made to communicate with
one or more copper bolts in contact with the exterior copper or
the water. It must be clear, therefbre, that this arrangement
preserves a permanent conductor so long as any part of the mast
is continued, and as the _masts of a ship may be considered as
mere points when contrasted with a thunder cloud, thus armed,
they are virtually pointed conductors. To those acquainted
with the action of points on charged electrics, it will be obvious,
and not too much to presume, that such masts will be highly
efficacious in silently depriving a thunder cloud of its charge,
thereby giving to ships a degree of security of very considerable
importance.
From these consideratidns Mr. Harris was induced to submit
a model of a complete mast, furnished with permanent conduc-
tors, to the inspection of the Honourable Navy Board, who ex-
pressed their decided approbation of the principle, and requested
him to exemplify its efficiency by an experiment, which was
carried into effect on Monday afternoon last, on board the Cale-
donia, in the presence of the Navy Board, Sir A. Cochrane,
Commissioner Shield, several Captains in the Navy, and the
principal officers of the Dock-yard, in the following manner :
The Louisa cutter having had a temporary mast and top-mast
fitted with a copper conductor, according to Mr. Harris's plan,
was moored astern of the Caledonia, and at the distance of
eighty feet front the cutter, a boat was stationed with a
small brasi howitzer. On the tiller head of the Caledonia
were placed the electrical machine and an electrical jar, with
the outer coating of which a line was connected, having a
metallic wire woven in it: this line being carried out of the
starboard window of the wardroom, terminated in an insulated
pointed wire in the immediate vicinity of the touch-hole of
the howitzer : a similar line was passed from the larboard win-
dow, which communicated with the mast-head of the cutter;
and at the termination of the bolt through the keel, a chain
was attached, connected with another insulated pointed wire
in the boat, placed in the vicinity -of the touch-hole—the
space between the insulated points being the only interval
in a circuit of about 300 feet from the positive to the nega-
tive side of the jar. Some gunpowder being placed in con-
tact with the conductor in the cutter, and the priming in
the interval of the insulated points, the jar was charged, and
the line attached to the mast-head of the cutter being
brought into contact with the positive or inside of the jar,
a discharge of electric matter followed, which was passed by
the line to the mast .head, and by the conductor through the
powder to the chain in the water, by which it was conveyed to the
interrupted communication in the boat, where it passed in the
form of a spark, and discharging the howitzer, returned to the
negative or outside of the jar by the line leading into the starboard
window, thereby demonstrating that a quantity of electric matter
had been passed by the conductor through the powder (without
igniting it) in contact with the mast of the cutter, sufficient to
discharge the howitzer. Mr. Harris then detached the commu-
nication between the keel .of the cutter and the positive wire in
the boat, leaving that wire to communicate with the water only ;
but this interruption did not impede or divert the charge, as
the discharge of the howitzer was effected with equal success as
in the first instance, the water forming the only conductor
from the cutter to the boat. In order to demonstrate that a
trifling fracture or interruption in the conductor would not be
important, it was cut through with a saw; but this produced
no material injury to its conducting power.
These trials, carried on under the disadvantages of unfavour-
able weather, could not fail of convincing all present of its
efficacy, and called forth the derided approbation of the Navy
Board in particular, which was evinced by Sir T. B. Martin
requesting Mr. Harris to superintend the equipment of the masts
of the Minden, 74, and Java frigate, preparatory to its general
introduction into the navy.
It can scarcely be necessary to expatiate on the degree of se-
curity the adoption of these conductors must afford; and we
trust the simplicity of their application will facilitate their intro-
duction into the merchants' service ; nor need we combat the
objection, should it be urged, that these injuries rarely occur,
since it will be sufficient to remember that many ships have
been damaged; and possibly sonic, whose fate has been unknown,
may have become the victims of neglect of the principle of
electrical conductors. It may not however be misplaced to state,
that a family in this town was deprived some years since of
a promising young man, by the explosion of a ship in the East
Indies, partly laden with gun-powder, occasioned by being
struck with lightning : or to record the more recent instance of
a French store-ship in the Mediterranean having a plank under
water displaced from the same cause, and was only saved from
sinking by being heeled over.