Herald of the times. [volume] (Newport, R.I.) 1830-1846, 1843-08-03
Protection from Lightning.


contains a lengthy communication from
Professor Olmstcd, of Yale Collcgc,
on the subject Of protection from light
ming. The writer is well known as Il
man of science, and we present some
extracts from his communication rela-
tive 10 lightning rods, believing his
views to be worthy of attention
Fully believing, therefore, in the eflicncy
and safety of the ordinary Franklin rod.
when well made aud applied, ! proceed t.
specify the proper mode Of construction and
application. The leading particulars which
require consideration. respect the material.
form, and Observation-Disclosures above
and below,-nnd npplicu,l"ns To buildings.
/ I-Malerial. Iron is the substance gen
orally employed for lightning rods, and it,
clhcsry has been established by experience.
\ 1t Is liable however To certain defects, against
which It is necessary to provide. the chief oi
which is its tendency tn rust. Rust greatly
diminishcs its conducting power, and OF
course impairs It's efficacy. Tins may be
prevented either 6y Keeping 1t well painted
with black paint, or by sablcc'ng 1t to the
process called galyaulzlne. Back paint iS
preferred To- other shades, because htin2
composed Of charcoal, 1t isa better conduc-
tor ,han The metol lic oSldes which form the
basis Of mos, other kinds o. paint.
L Copper has two drcIdrd advantages over
! IRON /: IT is from six Ia eight tunes better
! conductor than IRON, and Is not liable To have
lis conducting powers impaired by rust
| But It costs about 3 tunes u mnch aS iron,
aud therefore ~ not 80 likely 10 come int"
/ general use. In cases, however, where tn"
! additional expense is not deemed important,
! in consideration of the additional safety, ",
would recommend that lightning rods be
| made of copper.
\ Form and Dimensions. Round rods are
| those which have been longest in use, and
| when accompanied by The other essential
| requisites, they hre never been known 10
| fail. Some electricians, however, have urg-
4 cd a performance for square and rough bars
! instead Of the round aud smooth cylinders
usually employed, maintaining that such
| are better on two accounts, first, becaus"
when struck they suffer the charge nf cleo
| trrty TO escape by numerous Jets, at all the
| sharp lines and points throughout the length
| of the rod, whereas a round and sm oh cyln-
! der conducts ii in a concentrated form, re-
| 0uirnp that the whole shall escape at Nh
! lower termination or, If that fails to afford
/, a complete exit, increasing The liability IT,
/ leap from the rod in one formidable volume.
/ Secondly, they urge that such points ant
| lines favor the entrance into the rod Of such
/ charges as may approach it literally, where
( as the round rod only admits the charge o.
/ the top. am not acquainted with any en-.
! pciimcnts in electricity, of high authority
| winch prove that the conducting power %;
| rough iron il greater than that OF smooth.
other things being equal. The analogy oI
! fluids would lead Us to believe it to be les,
| II is said that, in certain cases where the
! rough rods have been struck, the lightning
has been seen To stream from the rod IN va
rious points, Throughout, its length, thus dis
persng the charge, and leaving bui rcs,dun
/ TO be conveyed TO the earth. Such un illu
' mna,ion of lho rod, itself usually implies n
I defective conductor when electricity passes
through good conductor capaclous enough ,t
transmit IL, 1t mani!ests 10 light A perfect
connexion with the ground will make lh'
lightning take iha, course, rather than dis
charge itself into the atmosphere.
III There may be cases when the course a.
lightning from the clouds To the earth ha,
been so diverted from a perpendicular dlrcc
} ton, tits usual ronte) az TO meet a lightning
rod a,eray instead of entering its pointed
summit. Such cases however are believed
TO be extremely rare. and require 10 be bet
ter authenticated. No such instance has
come to my knowledge ofa building being
struck latcrally. when armed with poo,
conductor az the common iorm-W hlle
therefore, | do not object to employing
conductor Ol the form uf nallrod, havln.
rough edges aud sharp poinls,i do not believe
N It has any advantages over smooth roun'
rod. Both will conduct the lightning harm
less ir continuous IN structure, aud well con
nccted with the earth neither will do It
defective ~ these respects. The SIZE Of lh
conductor may be, IN most cases, about thtc
, rnur,h~ of an inch diameter. Rods that ar
attached 10 very high buildings, as steeplc'
should be nj inch Some have suppose
, hat. since electricity pervndes the surface
T, ul conductors, u - not necessary that ih
' rod should hc solid, but that u would b
: equally good if made IN the form OF
. liupc but. ollliuuglI the fluid traverses III
y surface, yr, the conducting power ~ .propo'
!, liioned ln the solid uass; and thi- con-idcrO
,ion. as well as regard Ia strength. require
4 The parts 10 be solid. ln ordinary dIscharge
Iuf hyhlning, q smaller conductor Than VI
' one here recommend, d. would probably b
% sufficient: but ~ the most violent Discharge
u taganst which We w,b specially 10 provld'
:, smal,cf conductor, IS 1n non wHe, wOuI