116      Mr.  H.  Wilde  on  the  Influence  of  Gas-  and  Water-pipes 
The  ever  extending  introduction  of  gas-  and  water-pipes  into 
the  interior  of  buildings  armed  with  lightning-conductors  has, 
however,  greatly  altered  the  character  of  the  protection  which 
they  formerly  afforded ;  and  the  conviction  has  been  long  forced 
upon  me  that,  while  buildings  so  armed  are  effectually  protected 
from  injury  of  the  mechanical  kind,  they  are  more  subject  to 
damage  by  fire. 
The  proximity  of  lightning-conductors  to  gas-  and  water-mains, 
as  an  element  of  danger,  has  not  yet,  so  far  as  I  know,  engaged 
the  attention  of  electricians ;  and  it  was  first  brought  under  my 
notice  at  Oldham  in  1861,  by  witnessing  the  effects  of  a  light- 
ning discharge  from  the  end  of  a  length  of  iron  wire  rope, 
which  had  been  fixed  near  to  the  top  of  a  tall  factory  chimney, 
for  the  purpose  of  supporting  a  long  length  of  telegraph-wire. 
The  chimney  was  provided  with  a  copper  lightning-conductor 
terminating  in  the  ground  in  the  usual  manner.  In  close  proxi- 
mity to  the  conductor  and  parallel  with  it  the  wire  rope  descended, 
from  near  the  top  of  the  chimney,  for  a  distance  of  100  feet,  and 
was  finally  secured  to  an  iron  bolt  inserted  in  the  chimney  about 
10  feet  from  the  ground.  During  a  thunderstorm  which  oc- 
curred soon  after  the  telegraph-wire  was  fixed,  the  lightning  de- 
scended the  wire  rope,  and,  instead  of  discharging  itself  upon 
the  neighbouring  lightning-conductor,  darted  through  the  air 
for  a  distance  of  16  feet  to  a  gas-meter  in  the  cellar  of  an  ad- 
joining cotton  warehouse,  where  it  fused  the  lead-pipe  connexions 
and  ignited  the  gas.  That  the  discharge  had  really  passed  be- 
tween the  end  of  the  wire  rope  and  the  lead-pipe  connexions  was 
abundantly  evident  from  the  marks  made  on  the  chimney  by  the 
fusion  and  volatilization  at  the  end  of  the  wire  rope  and  by  the 
fusion  of  the  lead  pipe.  As  the  accident  occurred  in  the  daytime, 
the  fire  was  soon  detected  and  promptly  extinguished. 
Another  and  equally  instructive  instance  of  the  inductive  in- 
fluence of  gas-pipes  in  determining  the  direction  of  the  lightning 
discharge  occurred  in  the  summer  of  1863,  at  St.  Paul's  Church, 
Kersal  Moor,  during  divine  service.  To  the  outside  of  the  spire 
and  tower  of  this  church  a  copper  lightning-conductor  was  fixed, 
the  lower  extremity  of  which  was  extended  under  the  soil  for  a 
distance  of  about  20  feet.  The  lightning  descended  this  con- 
ductor, but,  instead  of  passing  into  the  earth  by  the  path  pro- 
vided for  it,  struck  through  the  side  of  the  tower  to  a  small  gas- 
pipe  fixed  to  the  inner  wall.  The  point  at  which  the  lightning 
left  the  conductor  was  about  5  feet  above  the  level  of  the  ground, 
and  tahe  thickness  of  the  wall  pierced  was  about  4  feet;  but 
beyond  the  fracture  of  one  of  the  outer  stones  of  the  wall  and 
the  shattering  of  the  plaster  near  the  gas-pipe,  the  building  sus- 
tained  no  injury. 
