3io  Papers  relative  to  an  Accident 
1 lhall  only  add,  that  if  any  one,  who  may  be  difpofed 
to  try  the  preceding  experiments,  will  ufe  an  apparatus  of 
fufficient  dimenfions,  and  faithfully  attend  to  every  cir- 
cumflance  as  I have  done,  I have  no  doubt  they  will  find 
the  fame  refults ; bvit  they  mtift  alfo  apply  their  obfervation 
to  much  fmaller  circumftances  than  have  been  here  fpe- 
cified,  as  the  intervention  of  a fingle  hair,  a fibre  of  down, 
or  even  a little  vapour  arifing  from  perfpiration  or  other- 
wife,  will,  where  great  exactnefs  is  required,  fometimes 
prevent  the  fuccefs  of  an  experiment;  and  by  that  means 
miflead  the  obferver,  or  afford  a fubterfuge  for  a miftaken 
hypothefis. 
Great  Ruffel-ibreet,  Bloomfbury, 
November  12,  17,77. 
N.  B.  The  different  diftances  at  which  the  point  and 
ball  were  if  ruck  being  expreffed  in  fractions,  p.  278.  I 
thought  it  would  be  better  to  put  thefe  diftances  in 
whole  numbers,,  that  the  ratio  between  them  may  more 
clearly  appear. 
Sharp  point.  Rounded  end.. 
90 
a-5 
160 
20 
130 
35 
220 
16 
260 
20 
80 
4 
Forty  of  thofe  parts,  are  equal  to  one  inch. 
Measure- 
