﻿IN 
  INCREASING 
  THE 
  INTENSITY 
  OF 
  ELECTRICITY. 
  225 
  

  

  wire 
  constantly 
  remained 
  in 
  the 
  other, 
  the 
  effect 
  was 
  noted. 
  The 
  first 
  

   length, 
  or 
  fifteen 
  feet, 
  gave 
  a 
  very 
  feeble 
  spark, 
  which 
  was 
  scarcely 
  per- 
  

   ceptible- 
  The 
  second, 
  or 
  thirty 
  feet, 
  produced 
  a 
  spark 
  a 
  little 
  more 
  

   intense, 
  and 
  the 
  effect 
  constantly 
  increased 
  with 
  each 
  additional 
  length 
  

   until 
  one 
  hundred 
  and 
  twenty 
  feet 
  were 
  used 
  ; 
  beyond 
  this 
  there 
  was 
  

   no 
  perceptible 
  increase 
  ; 
  and 
  a 
  wire 
  of 
  two 
  hundred 
  and 
  forty 
  feet 
  gave 
  

   a 
  spark 
  of 
  rather 
  less 
  intensity. 
  From 
  other 
  observations 
  I 
  infer, 
  that 
  

   the 
  length 
  necessary 
  to 
  produce 
  a 
  maximum 
  result, 
  varies 
  with 
  the 
  

   intensity 
  of 
  the 
  action 
  of 
  the 
  battery, 
  and 
  also 
  with 
  its 
  siz?. 
  

  

  3. 
  With 
  equal 
  lengths 
  of 
  copper 
  wire 
  of 
  unequal 
  diameters, 
  the 
  

   effect 
  was 
  greater 
  with 
  the 
  larger 
  : 
  this 
  also 
  appears 
  to 
  depend 
  in 
  some 
  

   degree 
  on 
  the 
  size 
  of 
  the 
  battery. 
  

  

  4. 
  A 
  length 
  of 
  about 
  forty 
  feet 
  of 
  the 
  wire 
  used 
  in 
  experinients 
  first 
  

   and 
  second, 
  was 
  covered 
  with 
  silk 
  and 
  coiled 
  into 
  a 
  cylindrical 
  helix 
  of 
  

   about 
  two 
  inches 
  in 
  height 
  and 
  the 
  same 
  in 
  diameter. 
  This 
  gave 
  a 
  

   more 
  intense 
  spark 
  than 
  the 
  same 
  wire 
  when 
  uncoiled. 
  

  

  5. 
  A 
  ribbon 
  of 
  sheet 
  copper 
  nearly 
  an 
  inch 
  wide 
  and 
  twenty-eight 
  

   and 
  a 
  half 
  feet 
  long, 
  was 
  covered 
  with 
  silk, 
  and 
  rolled 
  into 
  a 
  fiat 
  spiral 
  

   similar 
  to 
  the 
  form 
  in 
  which 
  woollen 
  binding 
  is 
  found 
  in 
  commerce. 
  

   With 
  this 
  a 
  vivid 
  spark 
  was 
  produced, 
  accompanied 
  by 
  a 
  loud 
  snap. 
  

   The 
  same 
  ribbon 
  uncoiled 
  gave 
  a 
  feeble 
  spark, 
  similar 
  in 
  intensity 
  to 
  

   that 
  produced 
  by 
  the 
  wire 
  in 
  experiment 
  third. 
  When 
  coiled 
  again 
  

   the 
  snap 
  was 
  produced 
  as 
  at 
  first. 
  This 
  was 
  repeated 
  many 
  times 
  in 
  

   succession, 
  and 
  always 
  with 
  the 
  same 
  result. 
  

  

  6. 
  To 
  test 
  still 
  farther 
  the 
  influence 
  of 
  coiling, 
  a 
  second 
  ribbon 
  was 
  

   procured 
  precisely 
  similar 
  in 
  length 
  and 
  in 
  all 
  other 
  respects 
  to 
  the 
  one 
  

   used 
  in 
  the 
  last 
  experiment. 
  The 
  effect 
  was 
  noted 
  with 
  one 
  of 
  these 
  

   coiled 
  into 
  a 
  fiat 
  spiral 
  and 
  the 
  other 
  uncoiled, 
  and 
  again 
  with 
  the 
  first 
  

   uncoiled 
  and 
  the 
  second 
  coiled. 
  When 
  uncoiled, 
  each 
  gave 
  a 
  feeble 
  

   spark 
  of 
  apparently 
  equal 
  intensity 
  ; 
  when 
  coiled, 
  a 
  loud 
  snap. 
  One 
  of 
  

   these 
  ribbons 
  was 
  next 
  doubled 
  into 
  two 
  equal 
  strands, 
  and 
  then 
  rolled 
  

   into 
  a 
  double 
  spiral 
  with 
  the 
  point 
  of 
  doubling 
  at 
  the 
  centre. 
  By 
  this 
  

   arrangement 
  the 
  electricity, 
  in 
  passing 
  through 
  the 
  spiral, 
  would 
  move 
  

   in 
  opposite 
  directions 
  in 
  each 
  contiguous 
  spire, 
  and 
  it 
  was 
  supposed 
  that 
  

   in 
  this 
  case 
  the 
  opposite 
  actions 
  which 
  might 
  be 
  produced 
  would 
  neu- 
  

   tralize 
  each 
  other. 
  The 
  result 
  was 
  in 
  accordance 
  with 
  the 
  anticipation 
  : 
  

  

  vol. 
  v. 
  — 
  3 
  G 
  

  

  