﻿1875.] 
  

  

  of 
  Dynamo-Magneio-Electric 
  Machine. 
  

  

  497 
  

  

  being 
  introduced, 
  one 
  was 
  employed 
  for 
  magnetizing 
  the 
  machine, 
  the 
  

   other 
  being 
  used 
  for 
  external 
  work. 
  This 
  machine 
  gave 
  a 
  good 
  electric 
  

   light 
  &c, 
  and 
  was 
  shown 
  in 
  the 
  Exhibition 
  of 
  Paris, 
  1867, 
  when 
  a 
  silver 
  

   medal 
  was 
  awarded 
  for 
  it. 
  

  

  To 
  simplify 
  this 
  machine, 
  the 
  author 
  of 
  this 
  paper 
  afterwards 
  placed 
  

   the 
  two 
  armatures 
  in 
  the 
  same 
  groove 
  between 
  the 
  poles 
  of 
  the 
  electro- 
  

   magnet, 
  bolting 
  the 
  two 
  together 
  at 
  right 
  angles 
  to 
  each 
  other, 
  so 
  that 
  

   they 
  came 
  under 
  the 
  influence 
  of 
  the 
  magnetism 
  alternately; 
  by 
  this 
  

   method 
  one 
  pair 
  of 
  bearings 
  was 
  sufficient 
  instead 
  of 
  two, 
  and 
  the 
  

   machine 
  altogether 
  was 
  much 
  simplified. 
  

  

  The 
  machine 
  now 
  about 
  to 
  be 
  described 
  is 
  a 
  still 
  further 
  modification, 
  

   in 
  which 
  the 
  greatest 
  amount 
  of 
  simplicity 
  and 
  effective 
  power 
  are 
  

   combined. 
  

  

  The 
  apparatus 
  consists 
  essentially 
  of 
  an 
  electromagnet 
  with 
  shoes, 
  

   forming 
  a 
  groove 
  in 
  which 
  a 
  Siemens's 
  armature 
  is 
  made 
  to 
  revolve 
  : 
  this 
  

   is 
  much 
  the 
  same 
  as 
  the 
  original 
  machines 
  made 
  by 
  Siemens 
  and 
  Wheat- 
  

   stone 
  ; 
  but 
  the 
  difference 
  occurs 
  in 
  the 
  break 
  or 
  commutator 
  ; 
  here 
  there 
  

   are 
  two 
  springs 
  or 
  rubbers 
  employed 
  in 
  taking 
  the 
  current 
  off 
  from 
  the 
  

   commutator. 
  The 
  commutator 
  consists 
  of 
  three 
  rings 
  : 
  one 
  of 
  these 
  rings 
  

   is 
  complete 
  for 
  three 
  quarters 
  of 
  the 
  circle, 
  the 
  other 
  quarter 
  being 
  cut 
  

   away 
  ; 
  another 
  ring 
  is 
  cut 
  away 
  three 
  quarters, 
  leaving 
  the 
  one 
  quarter 
  ; 
  

   and 
  in 
  between 
  these 
  two 
  rings 
  is 
  a 
  third 
  ring, 
  insulated 
  and 
  connected 
  

   with 
  the 
  insulated 
  end 
  of 
  the 
  wire 
  wound 
  round 
  the 
  armature 
  ; 
  on 
  this 
  

   centre 
  ring 
  are 
  projecting 
  pieces, 
  one 
  a 
  quarter 
  of 
  a 
  circle 
  and 
  the 
  other 
  

   three 
  quarters, 
  so 
  arranged 
  as 
  to 
  complete 
  the 
  two 
  outer 
  circles. 
  The 
  

   rubber 
  spring 
  which 
  comes 
  into 
  contact 
  with 
  the 
  quarter 
  of 
  the 
  middle 
  

   circle 
  is 
  connected 
  with 
  the 
  electromagnet 
  of 
  the 
  machine, 
  and 
  the 
  arma- 
  

   ture 
  is 
  so 
  arranged 
  that 
  at 
  the 
  time 
  of 
  contact 
  the 
  best 
  magnetizing 
  

   current 
  is 
  developed^ 
  The 
  other 
  spring 
  rubber 
  is 
  in 
  connexion 
  with 
  the 
  

   wire 
  on 
  the 
  armature 
  during 
  the 
  other 
  three 
  quarters 
  of 
  its 
  revolution 
  ; 
  

   and 
  this 
  is 
  connected 
  with 
  any 
  external 
  piece 
  of 
  apparatus 
  required 
  to 
  

   be 
  worked. 
  

  

  By 
  this 
  arrangement, 
  the 
  alternate 
  currents 
  being 
  utilized, 
  they 
  are 
  all 
  

   in 
  the 
  same 
  direction 
  ; 
  and 
  by 
  the 
  length 
  of 
  contact 
  the 
  whole 
  of 
  the 
  

   current 
  is 
  obtained 
  in 
  the 
  best 
  condition 
  for 
  heating 
  wires, 
  decomposing 
  

   water, 
  giving 
  an 
  electric 
  light, 
  and 
  other 
  usual 
  experiments. 
  

  

  At 
  present 
  a 
  model 
  machine 
  has 
  been 
  constructed 
  on 
  this 
  principle, 
  

   the 
  armature 
  of 
  which 
  measures 
  5 
  inches 
  long 
  by 
  2 
  inches 
  diameter, 
  on 
  

   which 
  is 
  wound 
  about 
  50 
  feet 
  of 
  cotton-covered 
  copper 
  wire, 
  no. 
  16, 
  

   B. 
  W. 
  Gr. 
  The 
  magnet 
  has 
  about 
  300 
  feet 
  of 
  covered 
  copper 
  wire, 
  

   no. 
  14, 
  B. 
  ~W. 
  Gr. 
  : 
  the 
  whole 
  instrument, 
  without 
  the 
  driving-gear, 
  

   weighs 
  26 
  lbs. 
  ; 
  with 
  this 
  apparatus 
  8 
  inches 
  of 
  platinum 
  wire, 
  *005, 
  

   can 
  be 
  made 
  red-hot, 
  water 
  is 
  rapidly 
  decomposed, 
  &c. 
  

  

  The 
  armature 
  is 
  constructed 
  specially 
  to 
  prevent 
  the 
  accumulation 
  of 
  heat 
  

   to 
  which 
  every 
  class 
  of 
  dynamo-magneto-electric 
  machine 
  is 
  liable. 
  It 
  is 
  

  

  2q2 
  

  

  