from  Lightning  at  Purfieet.  2,47 
ment  required : or,  at  leaft,  fo  as  to  equal  the  motion  of 
a thunder-cloud. 
An  apparatus  fufficiently  large  for  thefe  purpofes 
could  not  conveniently  be  put  in  motion:  therefore  I 
propofed  to  get  rid  of  this  difficulty,  by  moving  the 
building  itfelf,  inftead  of  the  fubftiture;  as  that  would 
anfwer  the  fame  end. 
In  order  to  obtain  a confiderable  charge  of  artificial 
lightning,  I propofed  to  have  one  great  cylinder  covered 
with  tin-foil , and  a wire  joined  to  one  end  of  it,  that 
fhould,  when  extended  properly,  confift  of  feverai  hun- 
dred yards. 
This  idea  leading  to  an  expence  too  confiderable  for 
an  individual,  I prefumed  to  hope  for  other  affiftance. 
Upon  an  humble  reprefentation  of  thefe  matters,  his 
Majefty,  who  is  always  difpofed  to  promote  every  pur- 
fuit  which  tends  to  the  advancement  of  fcience  and  the 
good  of  the  public,  moil  gracioufly  condefcended  to  en- 
courage the  undertaking;  and,  by  the  favour  of  the 
right  honorable  and  honorable  Board  of  Ordnance,  I 
was  immediately  enabled  to  carry  the  intended  plan  into 
execution. 
Very  foon  after  this  encouragement,  I procured  cor- 
reft  drawings  of  the  building  called  Lhe  Board-houfe  at 
Purfieet : from  thefe  an  exaft  model  was  made,  excepting 
the 
