﻿456 
  

  

  H. 
  D. 
  Day 
  — 
  Magnetic 
  Increment 
  

  

  The 
  data 
  obtained, 
  when 
  charted, 
  show 
  very 
  clearly 
  the 
  

   result 
  aimed 
  at 
  in 
  the 
  investigation. 
  The 
  accompanying 
  set 
  of 
  

  

  charts, 
  obtained 
  from 
  

   m^xx 
  uxu* 
  «&M'»i 
  , 
  ? 
  the 
  examination 
  of 
  a 
  

  

  <» 
  set 
  of 
  wires 
  whose 
  

   diameter 
  was 
  -294 
  mm 
  , 
  

   which 
  is 
  typical 
  of 
  the 
  

   entire 
  series, 
  is 
  suffi- 
  

   cient 
  to 
  exhibit 
  the 
  

   results 
  obtained. 
  

   Here, 
  80, 
  the 
  incre- 
  

   ment 
  of 
  twist 
  0, 
  is, 
  as 
  

   already 
  pointed 
  out, 
  

   a 
  very 
  approximate 
  

   relative 
  value 
  for 
  the 
  

   increment 
  of 
  rigidity, 
  

   if 
  be 
  taken 
  as 
  the 
  

   value 
  of 
  the 
  initial 
  

   twist. 
  The 
  values 
  of 
  

   80 
  and 
  are 
  to 
  be 
  

   applied 
  to 
  the 
  entire 
  

   length 
  of 
  both 
  wires, 
  

   namely, 
  50 
  cm 
  ; 
  for 
  it 
  

   is 
  readily 
  seen 
  that 
  80 
  

   represents 
  twice 
  the 
  

   actual 
  change 
  in 
  the 
  

   twist 
  of 
  either 
  wire. 
  

   Since, 
  however, 
  no 
  

   attempt 
  is 
  made 
  in 
  

   this 
  paper 
  to 
  give 
  an 
  

   absolute 
  value 
  for 
  the 
  

   increment 
  of 
  rigidity, 
  

   the 
  charts 
  exhibit 
  the 
  

   true 
  relations 
  existing 
  

   between 
  0, 
  80, 
  and 
  the 
  

   field-strength. 
  

  

  Fig. 
  2 
  shows 
  a 
  fam- 
  

   ily 
  of 
  curves 
  in 
  which 
  

   80 
  is 
  a 
  function 
  of 
  

   the 
  field-strength. 
  In 
  

   each 
  of 
  these 
  curves 
  

   80 
  is 
  an 
  increasing 
  

   function 
  of 
  the 
  field, 
  

   and 
  it 
  is 
  seen, 
  that 
  

   even 
  for 
  the 
  largest 
  

   fields 
  used, 
  the 
  incre- 
  

   ment 
  of 
  rigidity 
  shows 
  no 
  near 
  approach 
  to 
  a 
  limit 
  ; 
  moreover. 
  

  

  