from  Lightning  at  Purfleet.  265 
remained  in  the  cylinder  at  the  inftant  after  the  model 
had  paffed  it,  was  fo  confiderable,  that  there  appeared  no 
material  difference  whether  the  model  thus  circum- 
ftanced  was  fuffered  to  pafs  or  not. 
sixth  observation.  This  laft  experiment  fhews, 
that  a thunder-cloud  may  pafs  a conduit  or  fo  circum- 
ftanced  without  the  latter  being  ftruck,  or  fuffering  the 
leaft  injury ; which  it  will  not  do  in  other  circumftances, 
that  is,  when  the  conductor  is  pointed,  and  raifed  ten 
feet  above  the  building. 
exp.  xv.  On  repeating  the  fourteenth  experiment, 
but  with  a rounded  conductor,  which  was  three-fourths 
of  the  whole  length  of  that  in  the  twelfth  experiment 
(all  other  circumftances  remaining  the  fame)  and  after 
charging  the  cylinder  by  an  equal  number  of  turns,  it 
paffed  alfo  without  being  ftruck.  In  this  cafe,  the  re- 
maining charge  in  the  cylinder  was  fomething  lefs  than 
in  the  laft  experiment. 
seventh  observation.  This  is  a further  inftance  of 
the  advantage  derived  from  having  rounded  terminations 
of  a given  length  upon  a building,  compared  with ; 
pointed  ones,  that  are  only  two  or  three  feet  longer. 
Having  fo  far  experienced  the  different  effects  of  dif-- 
ferent  terminations  in  the  preceding  experiments,  it  may 
be  proper  to  mention  another  experiment,  where  the 
rounded 
