from  Lightning  at  Purfleet.  281 
exp.  xxix.  I then  made  a metallic  communication 
between  the  top  of  the  parapet  down  to  the  gutter : after 
this  the  experiment  was  repeated.  And  though  the  point 
was  ftruck  at  five  inches  diftance,  there  was  no  fpark 
whatfoever,  either  between  the  cramps  or  at  the  inner 
comer  next  to  the  gutter. 
twelfth  observation.  From  tliefe  laft  experiments 
it  appeared,  that  rain  contributed  to  make  the  lateral  effect 
greater  at  the  corner,  by  forming  a better  communica- 
tion between  the  cramps  and  the  gutter,  than  the  dry 
materials  of  brick  and  ftone  admitted  of.  But  it  alfo  ap- 
peared that,  when  the  communication  between  the  gut- 
ter and  cramps  was  rendered  more  perfect  by  a flip  of 
tin-foil  that  was  interpofed  between  them,  that  lateral 
effedt  ceafed  at  the  cramps;  becaufe  a ft  ill  freer  pafiage 
was  made  for  the  fluid  to  difcharge  itfelf  through ; not 
only  along  the  flip  of  metal  communicating  with  the 
gutters  and  the  tin-foil  quite  round  the  parapet,  but  alfo 
along  the  tin-foil  down  the  fide  of  the  model,  from , 
whence  it  was  conveyed  by  the  wire  to  the  well. 
exp.  xxx.  An  objection  having  been  made,  that  the 
wire  communicating  from  the  bottom  of  the  model  to  » 
the  well,  as  it  confifted  of  fever al  diftinct  parts,  occa- 
lioned  a refiftance  at  each  of  the  junctions,  and  therefore 
conftituted  only  an  imperfedt  conductor ; in  order  to  try 
the:; 
