Year: 1871

Are iiShtnlng rods OF any use WEat-
ever. and, If so, what material is most
suitable, iron or copper, or is .the old-fash-
ioned rod good as the best,n


CHAIR have already stated that in my
opinion, whether lightning rods are sure
protection or not they are valuable for the
sense of security they afford to the ladies
and children Of the family, if on no other
account. We have, however, with us to-
day, by invitation, Prof. John Phin, editor
of the Technologist, who is prepared to
give lis some valuable information on the
subject of lightning rods, and whom | am
sure we shall all be glad to listen to.


Prof. Phin-Whatever differences of OPP
inion may exist in regard to the authorship
of the discovery of the identity of light
ming and electricity, there can be none in
regard to the fact that Franklin, and Frank
lin alone, invented the lightning rod and,
strange to say, when it left his hands it
was nearly as perfect as it is to-day. Not
withstanding the many patents that have
been issued for alleged improvement in
| lightning-rods we would as soon trnst our
property to rod constructed after the di-
rectons given by the inventor as to one
made according to the latest devices, COW
cred by the broad seal of the United States
Patent Office. 1t is true that during the last
half century we have learned something
| about rods and their mode of action, and
have acquired more perfect knowledge
of the special points which demand atten-
ton, in the effort to secure perfect safety.
But it will be found, on examination, that
Franklin's old rod embodies all the points
necessary for perfect conductor, and that
consequently we are not at the mercy of
any patent right monopoly in this matter.
4 ifrhf mi orn I'm ara
many instances on record where buildings
furnished with rods have been struck and
injured. But this is not to he wondered
at, when we reflect that full one-half-nay,
perhaps three-fourths--of all the rods
erected violate the fundamental principles
upon which their efficiency depends. Be-
sides serious errors in regard to arrange
ment and continuity it will in general be
found that it is only by the merest acci-
dent that good ground connection is
ever secured. The Cathedral of st. Peter,
in Geneva, although so elvated as to be
above all other buildings in the neighbor-
hood, has for three centuries enjoyed per-
feet immunity from damage by lightning
while the tower of St. Gervaise although
much lower, has been frequently struck
This doubtless, arises from the fact that
all the towers of st. Peter are accidentally
furnished with the very perfect conductors.
| The great column of London, known as
the Monument, erected in 1917 in COM
memoration of the great fire, although
over.two hundred feet in height, has never
been struck, while much lower buildings
in the vicinity have not escaped. A still
more striking instance of the value of
| lightning-rods is afforded by a church on
the estate of Count Orsini, i'll Carinthia.



and had so often been struck by lightning
that it was deemed no longer safe to cele-
brate divine service within its walls. In
1870 single stroke of lightning destroy
ed the entire steeple after it had been
rebuilt it was struck on an average four or
five times a year, without counting extra
ordinary storms, during which it was
struck from five to ten times in single
day In 177S the building was recon
structed and furnished with a conductor;
and, according to Lichtenberg, up to 1888
that is to say during the space of tlve
years-the steeple had been struck only
once, and this stroke had fallen upon the
metallic point without producing any dam
age.


Next as to the material of which light
nign rods are to be made. Lightning rods
should be made OF the very best conduct
ing material, and of Il size sufficient to
carry off the heaviest discharge that is
ever likely to fall upon them. OF all we'll
known substances, metals are the best
conductors; and even among metals there
are great differences in this respect, some
metals, according to Becquerel, conduct
inc nearly seventy-tive times better than
some others. There are. however, but
two metals whose claims are worth con-
sderng-copper and iron. The others
are too costly.


Mr.. Lyman-Is there any advantage in
combining two metals, iron and copper.


Prof phin-NGne whatever. We speak
now OF the size of the rod. Great differ
euces of opinion exist in regard to the
size of rods necessary TO insure safety.
The old directions by the French Acade-
my of Sciences named a rod Of from one
halt inch to one inch square as safe
conductor The following extract from
the last report gives their latest views
upon this point: "A discharge of our
electric batteries is capable Of melting
several yards of very fine wire. a flash
of lightning is capable of volatilizing
more than one hundred yards of bell
wire, or of the wire that is usually em-
ployed in connection with the hammers
of public clocks


In 1927 upon the packet boat New York
Il surveyors chain forty yards long, made
of iron wire quarter of an inch in dame
ter which served as a lightning-rod on the
vessel, was melted by a flash of lightning
and dispersed in red hot fragments. No
instance has ever occurred in which light
ming has raised to red heat bar of iron
some yards long, and iour-tenths of an
inch square, or having n section OF one
sixth Of an inch square. Hence square
rod of iron, the sides being four-tenths OF
an inch, has been adopted in the construc-
ton of lightning-rods. This shows that
the enormous conductors recommended by
Prof Henry and others are unnecessarily
expensive and clumsy. When copper is
used the size may be proportionately re-
dueed. If iron is used, the rod should,
if square, be four-tenths of an inch on the
side; if copper, one-fourth of an Inch Is
sufficient