﻿496 
  

  

  Mr. 
  S. 
  C. 
  Tisley 
  on 
  a 
  new 
  Form 
  

  

  [June 
  17, 
  

  

  Correction 
  to 
  Prof. 
  Cayley's 
  u 
  Eighth 
  Memoir 
  on 
  Quantics. 
  

   Phil. 
  Trans. 
  Yol. 
  157 
  (1867). 
  Received 
  June 
  26, 
  1875. 
  

  

  The 
  Table 
  for 
  L, 
  M, 
  I/, 
  M', 
  p. 
  544, 
  should 
  stand 
  :— 
  

  

  72 
  L 
  = 
  

  

  

  72L' 
  = 
  

  

  24M' 
  = 
  

  

  

  

  A 
  3 
  I 
  +1 
  

  

  I-l 
  

  

  

  

  ABI 
  +3 
  

  

  

  A 
  2 
  B 
  2 
  C 
  -81 
  

  

  

  CI 
  -15 
  

  

  

  and 
  substituting 
  these 
  values 
  we 
  find 
  for 
  36a, 
  36b, 
  &c, 
  the 
  values 
  given 
  

   p. 
  554 
  ; 
  where 
  in 
  the 
  expression 
  of 
  36a, 
  the 
  term 
  A 
  2 
  B 
  2 
  C 
  — 
  126 
  should 
  have 
  

   been 
  distinguished 
  by 
  an 
  asterisk, 
  to 
  show 
  that 
  there 
  was 
  an 
  alteration 
  

   in 
  the 
  coefficient, 
  —126, 
  instead 
  of 
  —36 
  as 
  given 
  p. 
  544. 
  

  

  June 
  17, 
  1875. 
  

  

  JOSEPH 
  D 
  ALTON 
  HOOKER, 
  C.B., 
  President, 
  in 
  the 
  Chair. 
  

  

  The 
  Presents 
  received 
  were 
  laid 
  on 
  the 
  table, 
  and 
  thanks 
  ordered 
  for 
  

   them. 
  

  

  Prof. 
  John 
  Casey, 
  Dr. 
  August 
  Dupre, 
  and 
  Dr. 
  James 
  Hector 
  (who 
  

   was 
  elected 
  in 
  1866) 
  were 
  admitted 
  into 
  the 
  Society. 
  

  

  The 
  following 
  Papers 
  were 
  read 
  : 
  — 
  

  

  I. 
  " 
  On 
  a 
  new 
  Eorm 
  of 
  Dynamo-Magneto-Electric 
  Machine." 
  

   By 
  S. 
  C. 
  Tisley. 
  Communicated 
  by 
  W. 
  Spottiswoode, 
  M.A., 
  

   Treas. 
  U.S. 
  Received 
  June 
  17, 
  1875. 
  

  

  In 
  the 
  first 
  machines 
  constructed 
  by 
  Siemens 
  and 
  Wheatstone 
  in 
  1867 
  

   (see 
  Royal 
  Society's 
  Transactions) 
  the 
  power 
  of 
  augmenting 
  the 
  mag- 
  

   netism 
  by 
  successive 
  currents, 
  developed 
  from 
  the 
  original 
  residual 
  

   magnetism 
  contained 
  in 
  the 
  iron, 
  was 
  fully 
  demonstrated, 
  and 
  it 
  was 
  

   shown 
  that 
  the 
  power 
  of 
  the 
  machine 
  could 
  thereby 
  be 
  developed 
  to 
  a 
  

   great 
  extent 
  ; 
  but 
  the 
  only 
  means 
  for 
  obtaining 
  external 
  work 
  was 
  by 
  

   the 
  insertion 
  in 
  the 
  circuit 
  of 
  a 
  magnet 
  or 
  coil 
  so 
  that 
  the 
  secondary 
  

   discharge 
  could 
  be 
  .utilized. 
  Sir 
  Charles 
  Wheatstone 
  also 
  showed 
  that 
  

   a 
  great 
  part 
  of 
  the 
  current 
  could 
  be 
  shunted 
  through 
  a 
  platinum 
  wire, 
  

   care 
  being 
  taken 
  that 
  the 
  resistance 
  of 
  the 
  platinum 
  wire 
  was 
  sufficient 
  

   to 
  compel 
  a 
  large 
  part 
  of 
  the 
  current 
  to 
  pass 
  round 
  the 
  electromagnet. 
  

  

  In 
  the 
  same 
  year 
  the 
  writer 
  designed 
  a 
  machine 
  which 
  was 
  made 
  by 
  

   Mr. 
  Ladd, 
  and 
  described 
  by 
  him 
  in 
  a 
  paper 
  read 
  before 
  this 
  Society 
  (see 
  

   Transactions), 
  the 
  principle 
  of 
  which 
  was 
  that 
  two 
  separate 
  armatures 
  

  

  