﻿438 
  

  

  Dr. 
  C. 
  H. 
  Jones 
  on 
  Reversed 
  Th^acings 
  . 
  [May 
  27, 
  

  

  as 
  is 
  well 
  exemplified 
  in 
  fig. 
  IV. 
  ; 
  it 
  may 
  even 
  reduce 
  the 
  tracing 
  to 
  a 
  

   straight 
  line. 
  Beyond 
  this 
  it 
  seems 
  as 
  if 
  the 
  force 
  of 
  pressure 
  " 
  could 
  no 
  

   further 
  go 
  ; 
  " 
  it 
  is 
  unintelligible 
  how, 
  after 
  a 
  sufficient 
  force, 
  has 
  been 
  used 
  

   to 
  compress 
  the 
  artery, 
  a 
  greater 
  amount 
  of 
  force 
  should 
  produce 
  a 
  fall 
  

   and 
  subsequent 
  rise. 
  

  

  On 
  further 
  considering 
  these 
  tracings 
  it 
  seemed 
  very 
  important 
  to 
  

   determine 
  whether 
  the 
  rise 
  really 
  corresponded 
  to 
  the 
  rise 
  of 
  the 
  normal 
  

   tracing 
  or 
  not. 
  The 
  constant 
  presence 
  of 
  the 
  notch 
  in 
  the 
  apparent 
  

   rise 
  in 
  most 
  cases 
  suggested 
  that 
  this 
  was 
  perhaps 
  not 
  systolic 
  in 
  cardiac 
  

   time, 
  but 
  diastolic 
  ; 
  and 
  on 
  examination 
  this 
  proved 
  to 
  be 
  the 
  case 
  ; 
  for 
  

   while 
  the 
  sphygmograph 
  applied 
  to 
  Mr. 
  .Hawksley's 
  radial 
  was 
  giving 
  

   well-marked 
  falls 
  of 
  the 
  lever, 
  at 
  a 
  rate 
  below 
  70 
  per 
  minute, 
  I 
  observed, 
  

   by 
  feeling 
  the 
  other 
  radial, 
  that 
  each 
  drop 
  of 
  the 
  lever 
  coincided 
  exactly 
  

   with 
  the 
  beat 
  of 
  the 
  pulse, 
  and 
  was 
  therefore 
  systolic 
  in 
  time, 
  so 
  that, 
  of 
  

   course, 
  the 
  rise 
  must 
  have 
  been 
  diasystolic. 
  This 
  conclusion 
  was 
  subse- 
  

   quently 
  confirmed 
  by 
  observations 
  made 
  with 
  a 
  " 
  schema," 
  every 
  con- 
  

   traction 
  of 
  the 
  ball 
  causing 
  a 
  fall 
  of 
  the 
  lever 
  under 
  circumstances 
  to 
  be 
  

   immediately 
  mentioned. 
  The 
  " 
  schema 
  " 
  employed 
  was 
  rather 
  a 
  rude 
  

   affair, 
  only 
  a 
  Higginson's 
  syringe, 
  with 
  a 
  long 
  flexible 
  tube 
  attached, 
  the 
  

   open 
  orifice 
  of 
  which 
  was 
  obstructed 
  to 
  make 
  the 
  pressure 
  more 
  effectual. 
  

   When 
  the 
  elastic 
  tube 
  was 
  placed 
  under 
  the 
  spring 
  of 
  the 
  sphygmograph 
  

   every 
  contraction 
  of 
  the 
  ball 
  jerked 
  the 
  lever 
  up, 
  and 
  produced 
  such 
  a 
  

   tracing 
  as 
  is 
  represented 
  in 
  a, 
  fig. 
  V. 
  ; 
  but 
  when 
  the 
  tube 
  was 
  shifted 
  a 
  

   little 
  forwards 
  so 
  as 
  to 
  lie, 
  not 
  under 
  the 
  spring, 
  but 
  under 
  the 
  brass 
  plate 
  

   just 
  beyond 
  it, 
  then 
  every 
  contraction 
  of 
  the 
  ball 
  produced 
  a 
  sudden 
  fall 
  

   of 
  the 
  lever, 
  as 
  shown 
  in 
  h, 
  fig. 
  V. 
  The 
  pressure 
  of 
  the 
  brass 
  plate 
  

   when 
  a 
  was 
  obtained 
  was 
  little 
  more 
  than 
  2 
  oz., 
  when 
  b 
  was 
  obtained 
  

   it 
  was 
  30 
  oz. 
  But 
  that 
  the 
  increase 
  of 
  pressure 
  was 
  not 
  the 
  efficient 
  

   cause 
  of 
  the 
  lever 
  falling 
  instead 
  of 
  rising 
  is 
  shown 
  by 
  the 
  fact 
  that, 
  in 
  

   another 
  observation, 
  merely 
  shifting 
  the 
  position 
  of 
  the 
  elastic 
  tube 
  from 
  

   below 
  the 
  spring 
  to 
  below 
  the 
  brass 
  plate 
  sufficed 
  to 
  make 
  the 
  difference. 
  

   Simply 
  raising 
  the 
  brass 
  plate 
  by 
  taking 
  hold 
  of 
  the 
  screw 
  attached 
  to 
  

   the 
  framework 
  above 
  it 
  also 
  depressed 
  the 
  lever. 
  

  

  Erom 
  observations 
  recently 
  made 
  by 
  Mr. 
  Hawksley 
  on 
  his 
  arm, 
  we 
  

   were 
  unable 
  for 
  some 
  time 
  to 
  obtain 
  a 
  reversed 
  tracing, 
  or, 
  rather, 
  the 
  

   movement 
  of 
  the 
  lever 
  which 
  gives 
  it, 
  although 
  a 
  very 
  high 
  pressure 
  was 
  

   employed, 
  the 
  spring 
  being 
  made 
  to 
  rest 
  upon 
  the 
  radial 
  artery. 
  As 
  

   long 
  as 
  this 
  was 
  the 
  case 
  the 
  lever 
  either 
  remained 
  motionless 
  or 
  jerked 
  

   upwards 
  ; 
  but 
  when 
  the 
  brass 
  plate 
  at 
  the 
  distal 
  extremity 
  of 
  the 
  instru- 
  

   ment 
  was 
  intentionally 
  placed 
  over 
  the 
  artery, 
  the 
  spring 
  being 
  set 
  on 
  

   one 
  side, 
  the 
  lever 
  was 
  at 
  once 
  jerked 
  downwards, 
  and 
  my 
  friend, 
  who 
  had 
  

   been 
  sceptical 
  before, 
  was 
  quite 
  convinced 
  that 
  the 
  cause 
  of 
  reversed 
  

   tracings 
  is 
  the 
  malposition 
  of 
  the 
  instrument. 
  

  

  The 
  only 
  thing 
  which 
  makes 
  me 
  at 
  all 
  hesitate 
  to 
  rest 
  in 
  this 
  conclu- 
  

   sion 
  is, 
  that 
  it 
  does 
  not 
  explain 
  why 
  the 
  reversal 
  of 
  the 
  tracing 
  sometimes 
  

  

  