﻿with 
  Alternate 
  Current 
  Measuring 
  Instruments. 
  149 
  

  

  From 
  personal 
  experiment, 
  however, 
  the 
  author 
  has 
  found 
  

   that 
  the 
  value 
  44 
  is 
  more 
  nearly 
  correct 
  for 
  shell 
  type 
  

   transformers. 
  

  

  Experimental. 
  — 
  As 
  some 
  of 
  the 
  conclusions 
  arrived 
  at 
  are 
  

   of 
  importance, 
  and 
  are 
  somewhat 
  at 
  variance 
  with 
  existing 
  

   ideas, 
  some 
  experimental 
  evidence 
  will 
  be 
  of 
  value. 
  A 
  brief 
  

   reference 
  only 
  will 
  be 
  necessary 
  here 
  as 
  some 
  of 
  these 
  tests 
  

   have 
  already 
  been 
  published 
  *, 
  together 
  with 
  a 
  description 
  of 
  

   the 
  methods 
  by 
  which 
  the 
  results 
  were 
  obtained. 
  

  

  Fig. 
  3.— 
  Isometric 
  view 
  of 
  Transformer 
  Core. 
  

  

  The 
  principal 
  transformer 
  tested 
  was 
  made 
  for 
  the 
  tests, 
  

   and 
  was 
  of 
  the 
  shell 
  type 
  ; 
  the 
  core 
  having 
  a 
  magnetic 
  path 
  

   of 
  35*3 
  cm. 
  and 
  a 
  sectional 
  area 
  of 
  71 
  sq. 
  cm. 
  Four 
  inde- 
  

   pendent 
  coils, 
  each 
  of 
  150 
  turns 
  of 
  No. 
  18 
  D.C.C. 
  copper 
  

   wire, 
  were 
  wound 
  side 
  by 
  side, 
  the 
  resistance 
  of 
  each 
  coil 
  

   being 
  1*2 
  ohms. 
  Fig, 
  3 
  shows 
  the 
  core, 
  and 
  fig. 
  4 
  the 
  

  

  * 
  "Phase 
  Displacements 
  in 
  Resistances 
  and 
  Transformers," 
  Elec- 
  

   trician, 
  No. 
  lviii. 
  p. 
  160. 
  

  

  