304  Papers  relative  to  an  Accident 
fired  pretty  readily,  and  fometimes  with  the  great  cylin- 
der alone. 
exp.  l.  Before  the  apparatus  was  taken  down  in  the 
Pantheon,  attempts  were  made  feveral  days  to  fire  gun- 
powder, but  without  fuccefs,  except  in  one  inftance,  which 
was  attended  with  fome  difficulty.  This  failure  feemecl 
to  be  owing  to  a variety  of  caufes,  the  chief  of  which 
appeared  to  be  moifture  that  affected  the  filk  lines,  and 
perhaps  the  powder  itfelf.  I might  add  alfo  the  duft, 
which  in  fo  long  a time  had  fettled  upon  the  lines,  and 
rendered  them  in  fome  degree  incapable  of  refitting  the 
paflage  of  the  fluid.  However,  when  the  coiled  wires 
upon  the  filk  lines  were  properly  joined  to  the  long  wire, 
as  in  the  forty-ninth  experiment,  it  was  found  that  gun- 
powder could  be  fired  very  readily.  This  is  another 
proof  of  the  increafe  of  velocity  by  increafing  the  length 
of  the  wire. 
The  explofion  of  gun-powder,  in  the  particular  man- 
ner related  above,  without  the  afliftance  of  the  Leyden 
charge,  and  even  without  a fpark,  is  an  effect  which 
could  not  eafily  be  deduced  from  reafoning  upon  any 
experiments  hitherto  made ; for  though  gun-powder  has 
been  frequently  fired  with  the  Leyden  charge,  yet  there 
is  a difference  in  the  two  cafes,  which  makes  it  neceflary 
to  take  fome  farther  notice  of  that  experiment. 
When 
