﻿Circulation 
  of 
  the 
  Blood. 
  

  

  147 
  

  

  ordinary 
  sphygmograph, 
  differs 
  from 
  that 
  at 
  the 
  wrist 
  in 
  more 
  than 
  one 
  

   point. 
  The 
  primary 
  rise, 
  as 
  previously 
  mentioned, 
  is 
  less 
  abrupt 
  ; 
  the 
  

   following 
  fall 
  is 
  more 
  considerable, 
  and 
  is 
  not 
  broken 
  by 
  the 
  notch 
  

   nearly 
  constantly 
  seen 
  in 
  wrist 
  traces 
  of 
  this 
  rapidity. 
  The 
  secondary 
  

   rise 
  starts 
  from 
  a 
  lower 
  level 
  and 
  is 
  well 
  marked, 
  reaching 
  its 
  climax 
  

   considerably 
  nearer 
  the 
  nest 
  primary 
  rise 
  than 
  in 
  the 
  wrist 
  trace. 
  There 
  

   is, 
  however, 
  another 
  feature 
  in 
  the 
  early 
  part 
  of 
  the 
  secondary 
  rise 
  in 
  

   the 
  ankle 
  trace, 
  which 
  deserves 
  special 
  attention 
  because 
  of 
  its 
  general 
  

   occurrence. 
  As 
  is 
  well 
  known, 
  in 
  wrist 
  traces 
  the 
  secondary 
  rise 
  com- 
  

   mences 
  promptly 
  and 
  is 
  quite 
  uniform 
  in 
  character, 
  but 
  in 
  ankle 
  traces 
  

   there 
  is 
  nearly 
  always 
  a 
  short 
  horizontal 
  continuation 
  of 
  the 
  curve 
  im- 
  

   mediately 
  following 
  the 
  primary 
  fall, 
  the 
  point 
  of 
  departure 
  of 
  the 
  two 
  

   lines 
  being 
  clearly 
  indicated 
  by 
  an 
  abrupt, 
  though 
  not 
  considerable, 
  change 
  

   in 
  direction. 
  This 
  horizontal 
  portion 
  of 
  the 
  trace 
  is 
  not 
  of 
  any 
  con- 
  

   siderable 
  length, 
  being 
  in 
  a 
  pulse 
  of 
  70 
  a 
  minute 
  about 
  one 
  eighth 
  of 
  the 
  

   whole 
  beat 
  ; 
  it 
  is 
  followed 
  by 
  a 
  well-defined 
  secondary 
  rise, 
  which 
  is 
  much 
  

   longer 
  and 
  more 
  gradual 
  than 
  the 
  primary. 
  Though 
  described 
  above 
  as 
  

   horizontal, 
  this 
  short 
  interval 
  between 
  the 
  two 
  undulations 
  is 
  not 
  so 
  

   always, 
  being 
  frequently 
  slightly 
  oblique, 
  sometimes 
  in 
  one 
  direction, 
  

   sometimes 
  in 
  the 
  other. 
  When 
  its 
  curve 
  is 
  downwards 
  (that 
  is, 
  when 
  it 
  

   tends 
  in 
  the 
  same 
  direction 
  as 
  the 
  primary 
  fall), 
  it 
  may 
  appear 
  to 
  be 
  part 
  

   of 
  that 
  event, 
  which 
  would 
  then 
  look 
  as 
  if 
  broken 
  ; 
  when 
  its 
  curve 
  is 
  

   upwards 
  (that 
  is, 
  when 
  it 
  tends 
  in 
  the 
  same 
  direction 
  as 
  the 
  secondary 
  

   rise), 
  it 
  makes 
  the 
  trace 
  appear 
  more 
  normal 
  in 
  comparison 
  with 
  that 
  from 
  

   the 
  wrist. 
  

  

  Having 
  now 
  explained 
  the 
  ankle 
  sphygmograph-trace, 
  in 
  considering 
  

   the 
  simultaneous 
  wrist 
  and 
  ankle 
  traces 
  it 
  will 
  be 
  necessary 
  to 
  com- 
  

   mence 
  with 
  the 
  description 
  of 
  the 
  instrument 
  employed 
  to 
  obtain 
  them. 
  

   A 
  drawing 
  of 
  it 
  from 
  above 
  is 
  seen 
  in 
  Plate 
  5. 
  fig. 
  1, 
  from 
  the 
  side 
  in 
  

   fig. 
  2, 
  and 
  a 
  double 
  sphygmogram 
  is 
  given 
  in 
  fig. 
  4. 
  

  

  The 
  double 
  spliymograjpli 
  is 
  constructed 
  from 
  two 
  of 
  the 
  ordinary 
  sphyg- 
  

   mographs 
  of 
  Marey, 
  as 
  first 
  constructed 
  by 
  Breguet. 
  One, 
  that 
  employed 
  

   in 
  taking 
  the 
  ankle 
  trace, 
  retains 
  all 
  its 
  original 
  parts, 
  except 
  the 
  side 
  

   lappets 
  for 
  fixing 
  it 
  to 
  the 
  arm, 
  and 
  its 
  recording-apparatus 
  receives 
  the 
  

   double 
  trace. 
  A 
  second 
  lever 
  is 
  fixed 
  in 
  connexion 
  with 
  it 
  by 
  two 
  up- 
  

   rights 
  so 
  placed 
  as 
  to 
  allow 
  the 
  axis 
  of 
  the 
  second 
  lever 
  to 
  be 
  parallel 
  to 
  

   and 
  above 
  the 
  one 
  belonging 
  to 
  the 
  instrument, 
  sufficient 
  room 
  being 
  left 
  

   to 
  allow 
  the 
  latter 
  to 
  move 
  unobstructed 
  up 
  to 
  the 
  top 
  of 
  the 
  recording 
  

   paper. 
  This 
  second 
  lever, 
  which 
  is 
  a 
  facsimile 
  of 
  that 
  used 
  in 
  the 
  sphyg- 
  

   mograph, 
  is 
  placed 
  so 
  that 
  it 
  will 
  write 
  on 
  the 
  same 
  recording-paper 
  as 
  

   the 
  first 
  ; 
  but 
  its 
  position 
  is 
  reversed. 
  The 
  accompanying 
  sketch 
  (fig. 
  3) 
  

   will 
  show 
  this 
  point, 
  it 
  representing 
  a 
  side 
  view 
  of 
  the 
  ordinary 
  knife-edge 
  

   lever 
  upside 
  down 
  — 
  that 
  is, 
  with 
  the 
  surface 
  (s) 
  on 
  which 
  the 
  knife-edge 
  

   ought 
  to 
  slide 
  uppermost. 
  The 
  object 
  of 
  this 
  arrangement 
  will 
  be 
  seen 
  

   immediately. 
  

  

  The 
  second 
  sphygmograph 
  has 
  the 
  watchwork 
  removed, 
  as 
  well 
  as 
  the 
  

  

  