﻿R. 
  de 
  Saussure 
  — 
  Graphical 
  Thermodynamics. 
  21 
  

  

  This 
  retardation 
  of 
  the 
  level 
  in 
  E 
  is 
  of 
  considerable 
  import- 
  

   ance, 
  for 
  if 
  the 
  suction 
  tube 
  had 
  no 
  contraction 
  a 
  b 
  and 
  if 
  the 
  

   two 
  levels 
  in 
  E 
  and 
  D 
  were 
  continually 
  of 
  the 
  same 
  height 
  

   then 
  the 
  mercury 
  would 
  be 
  sucked 
  up 
  through 
  the 
  suction 
  tube 
  

   not 
  in 
  form 
  of 
  solid 
  columns 
  but 
  in 
  form 
  of 
  numerous 
  drops 
  

   separated 
  from 
  each 
  other 
  by 
  air 
  bubbles. 
  This 
  would 
  render 
  

   the 
  rapidity 
  of 
  action 
  less 
  satisfactory 
  ; 
  besides, 
  it 
  would 
  also 
  

   cause 
  a 
  rapid 
  oxidation 
  of 
  the 
  mercury. 
  

  

  As 
  soon 
  as 
  the 
  quantity 
  of 
  mercury 
  injected 
  into 
  A 
  brings 
  

   the 
  distance 
  between 
  the 
  level 
  in 
  A 
  and 
  the 
  point 
  f 
  into 
  the 
  

   vicinity 
  of 
  the 
  barometric 
  height 
  then 
  the 
  mercury 
  begins 
  to 
  

   overflow 
  from 
  the 
  syphon 
  tube 
  into 
  the 
  reservoir 
  B 
  and 
  the 
  

   exhausting 
  of 
  E 
  begins. 
  By 
  squeezing 
  the 
  tube 
  connecting 
  E 
  

   and 
  D 
  tbe 
  rapidity 
  of 
  supply 
  to 
  B 
  is 
  varied, 
  iience 
  the 
  quantity 
  

   of 
  mercury 
  in 
  B 
  can 
  thus 
  very 
  easily 
  be 
  kept 
  within 
  certain 
  

   desirable 
  limits. 
  

  

  The 
  simplicity 
  and 
  the 
  convenience 
  of 
  the 
  apparatus 
  need 
  

   m 
  comment. 
  Suffice 
  it 
  to 
  observe 
  that 
  it 
  has 
  no 
  stopcocks 
  and 
  

   that 
  it 
  can 
  operate 
  with 
  a 
  much 
  smaller 
  quantity 
  of 
  mercury 
  

   than 
  required 
  by 
  ordinary 
  mercury 
  pumps. 
  

  

  My 
  experiments 
  with 
  vacuum 
  tube 
  discharges 
  suggested 
  

   long 
  ago 
  to 
  my 
  mind 
  a 
  pump 
  of 
  this 
  type 
  ; 
  but 
  want 
  of 
  time 
  

   and 
  of 
  a 
  glass 
  blower 
  at 
  a 
  convenient 
  distance 
  prevented 
  me 
  

   from 
  giving 
  my 
  ideas 
  on 
  this 
  matter 
  a 
  practical 
  test, 
  until 
  last 
  

   summer.* 
  I 
  intend 
  to 
  publish 
  soon 
  numerical 
  data 
  concerning 
  

   the 
  rapidity 
  of 
  working 
  of 
  the 
  various 
  forms 
  of 
  pumps 
  of 
  this 
  

   type. 
  The 
  vacua 
  obtainable 
  by 
  it 
  are, 
  of 
  course, 
  the 
  same 
  as 
  

   those 
  obtainable 
  by 
  the 
  ordinary 
  form 
  of 
  the 
  Sprengel 
  pump. 
  

  

  Electrical 
  Laboratory, 
  Dec. 
  17 
  th, 
  1894. 
  Columbia 
  College, 
  New 
  York. 
  

  

  Art. 
  III. 
  — 
  On 
  Graphical 
  Thermodynamics 
  / 
  by 
  

   Rene 
  de 
  Saussure. 
  

  

  Translated 
  by 
  the 
  author 
  from 
  vol. 
  xxxi 
  of 
  the 
  Archives 
  des 
  Sciences 
  physiques 
  

   et 
  naturelles, 
  May, 
  1894. 
  

  

  1. 
  Heat 
  is 
  usually 
  regarded 
  as 
  a 
  periodical 
  motion 
  of 
  the 
  

   particles 
  constituting 
  the 
  material 
  bodies 
  ; 
  if 
  this 
  be 
  true, 
  the 
  

   variations 
  in 
  the 
  physical 
  state 
  of 
  *a 
  substance 
  are 
  due 
  to 
  the 
  

   variations 
  of 
  the 
  state 
  of 
  this 
  periodical 
  motion 
  ; 
  in 
  other 
  

   words, 
  the 
  physical 
  state 
  of 
  the 
  substance 
  is 
  a 
  function 
  of 
  the 
  

   state 
  of 
  the 
  periodical 
  motion. 
  Since 
  the 
  periodical 
  motion 
  of 
  

   the 
  particles 
  can 
  be 
  defined 
  by 
  its 
  kinetic 
  energy 
  and 
  by 
  the 
  

  

  * 
  [More 
  particular 
  details 
  of 
  construction 
  will 
  be 
  given 
  to 
  Messrs. 
  Eimer 
  & 
  

   Amend, 
  18th 
  Street 
  and 
  3d 
  Ave., 
  New 
  York, 
  and 
  to 
  Herr 
  Kramer, 
  Glasblaser, 
  

   Fridrich 
  Str., 
  Freiburg, 
  Baden 
  ] 
  

  

  