﻿132 
  Prof. 
  E. 
  H. 
  Barton 
  on 
  Range 
  and 
  

  

  rapidly, 
  then 
  it 
  pauses 
  or 
  even 
  increases 
  for 
  a 
  little 
  before 
  

   decreasing 
  a 
  second 
  time. 
  From 
  a 
  few 
  rough 
  trials, 
  it 
  

   appeared 
  that 
  for 
  the 
  wire 
  in 
  question, 
  with 
  a 
  vibrating 
  

   segment 
  70 
  cm. 
  long 
  tuned 
  to 
  128 
  per 
  second, 
  k 
  might 
  be 
  

   of 
  the 
  order 
  2 
  or 
  3 
  ; 
  for 
  the 
  same 
  length 
  vibrating 
  in 
  more 
  

   segments 
  k 
  appeared 
  to 
  be 
  still 
  larger. 
  We 
  might 
  accord- 
  

   ingly 
  have 
  the 
  sharpness 
  of 
  resonance 
  in 
  this 
  experiment 
  

   increasing 
  slower 
  than 
  the 
  frequency, 
  and 
  assuming 
  values 
  

   measured 
  by 
  some 
  hundreds. 
  They 
  are 
  not 
  inserted 
  in 
  the 
  

   table 
  however, 
  as 
  this 
  is 
  but 
  an 
  estimate, 
  and 
  cannot 
  yet 
  be 
  

   checked 
  by 
  the 
  known 
  values 
  of 
  the 
  responses. 
  

  

  Adjustable 
  Resonator 
  and 
  Forks. 
  — 
  A 
  very 
  simple 
  quali- 
  

   tative 
  illustration 
  of 
  the 
  dependence 
  of 
  the 
  sharpness 
  of 
  

   resonance 
  on 
  frequency 
  is 
  afforded 
  by 
  an 
  adjustable 
  water 
  

   resonator. 
  This 
  may 
  consist 
  of 
  an 
  upright 
  cylindrical 
  glass 
  

   tube 
  part 
  filled 
  with 
  coloured 
  water 
  in 
  communication 
  with 
  

   a 
  reservoir 
  which 
  may 
  be 
  slid 
  up 
  and 
  down 
  a 
  standard. 
  The 
  

   illu-tration 
  may 
  then 
  be 
  carried 
  out 
  as 
  follows. 
  

  

  First, 
  find 
  by 
  a 
  preliminary 
  trial 
  the 
  position 
  of 
  the 
  water- 
  

   level 
  which 
  leaves 
  in 
  the 
  tube 
  an 
  air 
  column 
  in 
  best 
  re- 
  

   sonance 
  with 
  a 
  given 
  fork, 
  of 
  frequency 
  128 
  say. 
  Second, 
  

   set 
  the 
  reservoir 
  a 
  little 
  too 
  high 
  (or 
  too 
  low) 
  on 
  the 
  standard, 
  

   and 
  put 
  on 
  the 
  standard 
  a 
  stop 
  (the 
  thumb 
  and 
  finger 
  of 
  the 
  

   left 
  hand, 
  say) 
  which 
  will 
  allow 
  the 
  reservoir 
  to 
  be 
  quickly 
  

   moved 
  a 
  determinate 
  distance 
  to 
  a 
  place 
  equally 
  too 
  low 
  (or 
  

   too 
  high). 
  Then, 
  when 
  the 
  fork 
  is 
  bowed 
  and 
  held 
  over 
  the 
  

   resonance-tube 
  by 
  one 
  operator, 
  the 
  other 
  must 
  quickly 
  move 
  

   the 
  reservoir 
  from 
  one 
  stop 
  to 
  the 
  other. 
  The 
  effect 
  of 
  this 
  

   is 
  that 
  the 
  water-level 
  soon 
  passes 
  (and 
  always 
  at 
  the 
  same 
  

   definite 
  speed) 
  the 
  position 
  of 
  best 
  resonance. 
  The 
  sounds 
  

   just 
  before 
  and 
  after 
  the 
  best 
  resonance 
  are 
  thus 
  heard, 
  and 
  

   the 
  suddenness 
  of 
  the 
  changes 
  in 
  loudness 
  may 
  be 
  noted. 
  

   The 
  experiment 
  is 
  then 
  repeated 
  with 
  a 
  higher 
  fork 
  capable 
  

   of 
  eliciting 
  a 
  response 
  from 
  the 
  same 
  column. 
  Its 
  frequency 
  

   must 
  be 
  ('2m 
  + 
  1) 
  times 
  that 
  of 
  the 
  fundamental, 
  where 
  m 
  is 
  

   any 
  integer 
  ; 
  since 
  the 
  resonance 
  system 
  is 
  the 
  air 
  in 
  a 
  

   stopped 
  pipe. 
  Thus 
  a 
  fork 
  of 
  384 
  ( 
  — 
  3 
  x 
  128) 
  would 
  serve 
  for 
  

   the 
  present 
  case, 
  and 
  was 
  adopted. 
  

  

  The 
  changes 
  in 
  loudness 
  are 
  easily 
  heard 
  to 
  be 
  more 
  sudden 
  

   in 
  the 
  case 
  of 
  the 
  higher 
  fork. 
  

  

  As 
  this 
  is 
  not 
  a 
  case 
  in 
  which 
  one 
  can 
  readily 
  commit 
  to 
  

   paper 
  a 
  quantitative 
  statement 
  of 
  what 
  is 
  heard, 
  independent 
  

   witnesses 
  were 
  invited 
  to 
  listen 
  and 
  to 
  describe 
  what 
  was 
  

   heard 
  or 
  to 
  sketch 
  a 
  graph 
  for 
  it. 
  In 
  this 
  way 
  Mr. 
  Walter 
  

   B. 
  Kilbf, 
  Research 
  Scholar, 
  Mr. 
  A. 
  H. 
  Franks, 
  Lecture 
  

   Assistant, 
  and 
  Mr. 
  W 
  . 
  M. 
  Koskelly, 
  Student, 
  all 
  confirmed 
  

  

  