from  Lightning  at  Purfleet.  249, 
horizontal,  till  it  reached  within  two  inches  (or  little 
more)  of  the  fliort  wrire : after  which  it  was  bent  again 
almoft  at  a right  angle,  and  then  lengthened  out  to  the 
bottom  of  the  model,  from  whence  it  communicated,  by 
another  wire,  with  a pump  or  well,  in  another  part  of 
the  houfe. 
This  kind  of  communication  was  neceffary,  becaufe, 
confifting  of  metal,  it,  in  that  refpe<ft,  was  fimilar  to  the 
communication  at  Purfleet. 
Befides  the  two  cramps  mentioned  above,  another  pa- 
rapet was  made  to  put  on  occafionally,  which  contained  all 
the  cramps : thefe  were  properly  fixed  therein,  and  at  their 
proper  diftances  from  each  other.  And  the  Royal  Society 
having  thought  proper,  fince  the  accident,  to  order  that 
a metallic  communication  fliould  be  made  between  the 
cramps  upon  the  parapet,  quite  round  the  building,  as  a 
better  fecurity  from  fuch  accidents  for  the  future,  care 
Was  taken  to  make  a fimilar  connexion  with  the  wire 
cramps,  by  means  of  fmall  flips  of  tin-foil  that  were 
pafted  upon  the  parapet  of  this  model. 
On  the  top  of  the  roof  in  the  middle,  conductors  of 
different  lengths  and  terminations  were  occafionally  put, 
juft  as  the  experiments  required. 
The  fcale  from  which  this  model  was  made,  when 
compared! 
