374  Tapers  relative  to  an  Accident 
.tenths  in  diameter,  that  was  covered  with  the  fame  metal, 
and  projected  from  the  center  of  the  nearer  end  of  the 
great  cylinder  by  a kind  of  item  made  of  wood,  and  co- 
vered with  tin-foil  alfo,  which  was  fix  or  feven  inches 
long.  Being  fo  prepared,  the  model  was  fet  upon  a table, 
directly  under  the  ball  at  the  remote  end  of  the  lefs 
fubftitute,  with  the  pointed  conductor  upon  it : and  all 
the  wires  were  properly  connected,  fo  as  to  make  a free 
communication  between  the  model  and  the  well. 
Nothing  now'  remained  but  to  put  the  machine  in  mo- 
tion ; when,  after  ten  turns  of  the  wheel,  the  point  upon 
the  model  was  ftruck  at  the  diftance  of  four  inches. 
In  the  twelfth  experiment,  where  the  model  w'as  in 
motion,  the  point  was  ftruck  at  the  diftance  of  five  inches 
nearly  from  the  cylinder.  This  difference  of  diftance  in 
thefe  two  experiments  feemed  to  arife  chiefly  from  a dif- 
ference in  the  ftates  of  the  air,  it  being  rather  unfa- 
vourable w'hen  the  eighteenth  experiment  was  tried. 
exp.  xix.  However,  fome  time  after,  when  the  ftate 
of  the  air  was  very  favourable,  I repeated  the  laft  expe- 
riment, and  obferved  that  the  point  w'as  ftruck  at  fix 
inches  and  one  quarter. 
During  this  laft  experiment,  a perfon,  Handing  upon 
the  wire  of  communication,  placed  his  finger  in  contact 
with  the  pointed  condu£tor  (near  the  bottom)  at  the  time 
the 
