﻿into 
  the 
  'Skin 
  '-effect 
  in 
  Electrical 
  Oscillators. 
  437 
  

  

  the 
  secondary 
  of 
  an 
  induction-coil 
  across 
  to 
  the 
  side 
  of 
  the 
  

   room, 
  and 
  sparks 
  were 
  made 
  to 
  pass 
  between 
  the 
  ordinary 
  

   pointed 
  terminals 
  of 
  the 
  coil. 
  The 
  coil 
  was 
  in 
  the 
  basement 
  

   of 
  the 
  laboratory. 
  A 
  fully 
  magnetized 
  detector, 
  with 
  wings 
  

   each 
  about 
  90 
  cms. 
  long 
  arranged 
  parallel 
  to 
  the 
  wire 
  running 
  

   out 
  from 
  the 
  coil, 
  was 
  placed 
  in 
  position 
  by 
  the 
  magneto- 
  

   meter, 
  giving 
  the 
  usual 
  deflexion 
  of 
  40 
  cms. 
  The 
  magneto- 
  

   meter 
  was 
  in 
  a 
  room 
  on 
  the 
  next 
  floor 
  above, 
  and 
  was 
  distant 
  

   about 
  35 
  metres, 
  with 
  brick 
  walls, 
  numberless 
  wires 
  and 
  

   other 
  pieces 
  of 
  metal 
  between 
  ; 
  and 
  yet, 
  as 
  soon 
  as 
  sparks 
  

   began 
  to 
  pass 
  at 
  the 
  coil, 
  the 
  magnetometer 
  deflexion 
  was 
  

   reduced 
  by 
  2 
  cms. 
  

  

  The 
  detector 
  was 
  also 
  used 
  to 
  determine 
  the 
  wave-length 
  

   of 
  the 
  oscillators 
  used. 
  The 
  wave-length 
  for 
  the 
  cylinders 
  

   was 
  found 
  to 
  be 
  approximately 
  80 
  cms. 
  ; 
  that 
  for 
  the 
  10 
  cm. 
  

   spheres 
  approximately 
  38*5 
  cms., 
  i. 
  e. 
  3'85 
  times 
  the 
  

   diameter. 
  An 
  account 
  of 
  these 
  experiments 
  will 
  be 
  published 
  

   later. 
  Using 
  these 
  results 
  the 
  frequencies 
  given 
  in 
  Table 
  I. 
  

   were 
  obtained. 
  

  

  4. 
  Experiments 
  on 
  the 
  ' 
  Skin 
  '-effect. 
  

  

  During 
  the 
  study 
  of 
  the 
  ' 
  skin 
  '-effect 
  cylindrical 
  oscillators 
  

   with 
  the 
  dimensions 
  given 
  above 
  were 
  made 
  as 
  follows 
  : 
  — 
  

  

  No. 
  1. 
  Solid 
  brass. 
  

  

  No. 
  2. 
  Solid 
  Norway 
  iron. 
  

  

  No. 
  3 
  & 
  No. 
  4. 
  Copper 
  1*5 
  inm. 
  and 
  0*8 
  mm. 
  thick 
  respectively. 
  

  

  The 
  mantle 
  was 
  of 
  copper 
  tubing 
  and 
  the 
  hemispherical 
  

  

  ends 
  were 
  spun 
  and 
  then 
  soldered 
  on. 
  

   No. 
  5. 
  Solid 
  electric 
  -light 
  carbon. 
  

   No. 
  6. 
  Sheet 
  platinum, 
  over 
  a 
  wooden 
  form. 
  The 
  mantle 
  was 
  

  

  0-0013 
  cm. 
  thick 
  ; 
  the 
  hemispherical 
  ends, 
  which 
  were 
  

  

  soldered 
  on, 
  were 
  0-015 
  cm. 
  thick. 
  

   No. 
  7. 
  Sheet 
  silver. 
  Mantle, 
  0*002 
  cm. 
  ; 
  ends, 
  0-014 
  cm. 
  

   No. 
  8. 
  Tin-foil, 
  0-0025 
  cm. 
  thick, 
  on 
  a 
  wooden 
  form. 
  

   No. 
  9. 
  Gold-leaf 
  laid 
  upon 
  a 
  wooden 
  form. 
  According 
  to 
  

  

  manufacturer, 
  the 
  leaf 
  was 
  about 
  1/220,000 
  inch, 
  or 
  

  

  0-0000114 
  cm. 
  thick. 
  

  

  No. 
  10. 
  Silver-leaf 
  laid 
  upon 
  wood. 
  Thickness 
  about 
  0-00003 
  cm. 
  

  

  Upon 
  cylinders 
  covered 
  with 
  gold-leaf, 
  copper 
  was 
  deposited 
  

  

  electrolvticall)', 
  the 
  thickness 
  of 
  the 
  copper 
  being 
  in 
  

  

  No. 
  11, 
  No. 
  12, 
  No. 
  13, 
  No. 
  14, 
  No. 
  15, 
  respectively, 
  

  

  0-0001, 
  0-00015, 
  0-0002, 
  0-0003, 
  0-0005 
  cm. 
  

  

  No. 
  16. 
  Silver 
  deposited 
  chemically 
  on 
  glass 
  blown 
  to 
  the 
  proper 
  

  

  shape. 
  The 
  thickness, 
  obtained 
  by 
  weighing, 
  was 
  

  

  approximately 
  0-000013 
  cm. 
  

  

  In 
  order 
  to 
  have 
  the 
  ends 
  between 
  which 
  the 
  sparks 
  were 
  

  

  