﻿Dielectric 
  Constant 
  of 
  Paraffins. 
  55 
  

  

  of 
  the 
  primary 
  rigidly 
  in 
  place. 
  When 
  the 
  coils 
  are 
  in 
  use 
  

   the 
  jar 
  is 
  filled 
  with 
  kerosene. 
  

  

  The 
  first 
  bridge 
  B 
  2 
  (fig. 
  3) 
  rests 
  in 
  a 
  groove 
  in 
  the 
  rubber 
  

   support. 
  It 
  is 
  30 
  mm. 
  long, 
  1 
  mm. 
  thick, 
  and 
  3 
  mm. 
  wide. 
  

   It 
  has 
  two 
  holes 
  in 
  which 
  to 
  receive 
  the 
  ends 
  of 
  the 
  secondary, 
  

   and 
  these, 
  when 
  in 
  place, 
  are 
  soldered 
  to 
  the 
  bridge. 
  Two 
  

   grooves 
  symmetrically 
  placed 
  are 
  filed 
  on 
  top 
  of 
  the 
  bridge, 
  

   1*8 
  cm. 
  apart. 
  The 
  Lecher 
  wires 
  L 
  rest 
  in 
  these 
  grooves 
  

   and 
  are 
  clamped 
  firmly 
  to 
  the 
  bridge 
  by 
  means 
  of 
  the 
  top 
  of 
  

   the 
  rubber 
  support, 
  which 
  is 
  furnished 
  with 
  two 
  strong 
  brass 
  

   screws. 
  The 
  other 
  ends 
  of 
  the 
  Lecher 
  wires 
  1/8 
  cm. 
  apart 
  

   are 
  clamped 
  in 
  a 
  second 
  rubber 
  support. 
  The 
  supports, 
  about 
  

   150 
  cm. 
  apart, 
  are 
  strong 
  enough 
  to 
  allow 
  a 
  tension 
  of 
  several 
  

   pounds 
  on 
  the 
  wires. 
  Unless 
  otherwise 
  designated, 
  the 
  

   Lecher 
  wires 
  are 
  made 
  of 
  no. 
  18 
  copper 
  wire. 
  

  

  The 
  second 
  and 
  movable 
  bridge 
  B 
  2 
  is 
  a 
  brass 
  wire 
  1 
  mm. 
  in 
  

   diameter 
  and 
  4 
  cm. 
  long. 
  The 
  post 
  holding 
  the 
  bridge 
  works 
  

   in 
  a 
  socket 
  containing 
  a 
  spring 
  which 
  presses 
  the 
  bridge 
  

   against 
  the 
  two 
  wires. 
  The 
  base 
  of 
  the 
  bridge-holder 
  has 
  an 
  

   index 
  extending 
  over 
  a 
  metre-rod, 
  thus 
  indicating 
  the 
  position 
  

   of 
  the 
  bridge. 
  

  

  P 
  is 
  a 
  Pliicker 
  argon 
  tube, 
  mounted 
  in 
  such 
  a 
  way 
  that 
  it 
  

   may 
  be 
  moved 
  at 
  will 
  along 
  the 
  three 
  mutually 
  perpendicular 
  

   directions. 
  Tubes 
  filled 
  with 
  other 
  gases 
  were 
  tried, 
  but 
  

   none 
  of 
  these 
  glowed 
  with 
  such 
  brilliancy. 
  Professors 
  John 
  

   Trowbridge 
  and 
  T. 
  W. 
  Richards* 
  have 
  called 
  attention 
  to 
  

   the 
  unusual 
  sensitiveness 
  of 
  an 
  argon 
  tube 
  to 
  oscillating 
  dis- 
  

   charges. 
  In 
  order 
  to 
  observe 
  the 
  glow 
  of 
  the 
  tube 
  to 
  the 
  

   best 
  advantage, 
  it 
  is 
  necessary 
  to 
  work 
  in 
  a 
  darkened 
  room. 
  

  

  Some 
  Preliminary 
  Experiments, 
  

   (a) 
  Determination 
  of 
  the 
  Line 
  Constants. 
  

  

  In 
  this 
  adjustment 
  of 
  the 
  oscillator 
  the 
  primary 
  was 
  made 
  

   of 
  copper 
  wire 
  2 
  mm. 
  in 
  diameter, 
  and 
  was 
  furnished 
  with 
  

   discharging 
  balls 
  4 
  mm. 
  in 
  diameter. 
  The 
  diameter 
  of 
  the 
  

   coil 
  was 
  4 
  cm. 
  The 
  total 
  length 
  of 
  the 
  secondary, 
  including 
  

   the 
  leading-out 
  wires 
  to 
  the 
  first 
  bridge, 
  was 
  about 
  25 
  cm. 
  

   In 
  every 
  case 
  the 
  secondary 
  is 
  made 
  of 
  no. 
  18 
  copper 
  wire. 
  

   The 
  wave-length 
  given 
  out 
  by 
  such 
  a 
  combination 
  when 
  

   the 
  primary 
  was 
  *3 
  mm. 
  from 
  the 
  secondary 
  was 
  61*33 
  cm. 
  

   In 
  order 
  to 
  determine 
  the 
  exact 
  wave-length 
  one 
  may 
  pro- 
  

   ceed 
  as 
  follows 
  : 
  — 
  Place 
  the 
  argon 
  tube 
  under 
  the 
  wires, 
  in 
  

   contact 
  with 
  them, 
  and 
  about 
  14 
  cm. 
  from 
  the 
  first 
  bridge. 
  

   Slide 
  the 
  movable 
  bridge 
  along 
  the 
  wires 
  until 
  the 
  first 
  

   * 
  American 
  Journal 
  of 
  Science, 
  vol. 
  cliii. 
  p. 
  19 
  (1897). 
  

  

  