﻿346 
  Dr. 
  S. 
  Tolver 
  Preston 
  on 
  some 
  Physical 
  Relations 
  

  

  pressure 
  about 
  a 
  small 
  object 
  (say 
  a 
  sphere 
  * 
  of 
  finite 
  radius) 
  

   by 
  the 
  simplest 
  kinetic 
  medium 
  composed 
  of 
  particles 
  of 
  

   matter 
  or 
  " 
  corpuscules 
  " 
  in 
  a 
  normal 
  state 
  of 
  motion. 
  The 
  

   absence 
  of 
  a 
  universal 
  agreement 
  as 
  to 
  the 
  ultimate 
  constitution 
  

   of 
  Matter, 
  does 
  not 
  prevent 
  the 
  deduction 
  of 
  certain 
  physical 
  

   relations 
  rigorously 
  resulting 
  from 
  given 
  premisses. 
  

  

  The 
  more 
  the 
  material 
  constituting 
  our 
  physical 
  agent 
  

   (sometimes 
  termed 
  " 
  medium 
  ") 
  diffused 
  in 
  space 
  is 
  sub- 
  

   divided, 
  the 
  more 
  equable 
  evidently 
  will 
  the 
  pressure 
  

   (kinetic) 
  about 
  the 
  said 
  finite 
  small 
  sphere 
  become, 
  until, 
  in 
  

   the 
  limit, 
  by 
  progressive 
  subdivision 
  of 
  the 
  material, 
  the 
  

   pressure 
  comes 
  to 
  rival 
  in 
  steadiness 
  that 
  of 
  a 
  perfectly 
  

   continuous 
  fluid. 
  Yet, 
  at 
  the 
  same 
  time, 
  the 
  medium 
  might 
  

   represent 
  a 
  Vacuity 
  far 
  surpassing 
  that 
  of 
  any 
  " 
  Vacuum 
  " 
  

   artificially 
  obtainable, 
  in 
  regard 
  to 
  relatively 
  small 
  pro- 
  

   portion 
  of 
  material 
  contained 
  in 
  the 
  medium, 
  compared 
  with 
  

   the 
  total 
  (pervaded) 
  space. 
  

  

  In 
  this 
  way, 
  by 
  simple 
  subdivision, 
  a 
  single 
  molecule 
  of 
  gross 
  

   matter 
  might 
  be 
  imagined 
  capable 
  of 
  pervading 
  the 
  range 
  of 
  

   the 
  visible 
  Cosmos, 
  — 
  with 
  minute 
  "corpuscules" 
  in 
  close 
  proxi- 
  

   mity 
  (reckoned 
  from 
  centre 
  to 
  centre). 
  It 
  may 
  possibly 
  be 
  well 
  

   to 
  realize 
  that 
  there 
  is 
  no 
  assignable 
  limit 
  (practically 
  speaking) 
  

   to 
  this 
  procedure, 
  in 
  conception 
  at 
  least 
  : 
  and 
  thus 
  dimen- 
  

   sions 
  actually 
  measured 
  or 
  calculated 
  may 
  possibly 
  be 
  easier 
  

   brought 
  within 
  mental 
  grasp, 
  in 
  connexion 
  with 
  the 
  Cor- 
  

   puscular 
  view 
  of 
  Matter. 
  

  

  " 
  Continuity 
  " 
  may 
  (additionally) 
  refer 
  to 
  that 
  sensible 
  

   physical 
  continuity, 
  in 
  reference 
  to 
  the 
  impossibility 
  of 
  directly 
  

   detecting 
  any 
  trace 
  of 
  structure 
  anywhere 
  in 
  our 
  medium, 
  on 
  

   account 
  of 
  its 
  dimensional 
  properties 
  eluding 
  direct 
  appre- 
  

   ciation 
  by 
  the 
  senses 
  ; 
  so 
  that 
  the 
  appearance 
  is 
  presented 
  of 
  

   the 
  continuity 
  of 
  a 
  fluid. 
  Thus 
  the 
  extremes 
  of 
  Vacuity 
  and 
  

   of 
  Continuity 
  may 
  be 
  said 
  " 
  to 
  meet," 
  — 
  in 
  a 
  certain 
  physical 
  

   signification. 
  

  

  That 
  the 
  " 
  mean 
  length 
  of 
  path," 
  by 
  this 
  process 
  of 
  sub- 
  

   division 
  of 
  material, 
  also 
  diminishes 
  continuously 
  in 
  the 
  same 
  

  

  * 
  Given 
  a 
  normal 
  velocity 
  for 
  the 
  constituent 
  particles, 
  the 
  sensible 
  

   uniformity 
  of 
  the 
  pressure 
  of 
  a 
  medium 
  [say 
  our 
  atmosphere] 
  upon 
  

   a 
  small 
  body 
  immersed 
  therein, 
  evidently 
  does 
  not 
  depend 
  on 
  the 
  size 
  

   of 
  the 
  impinging 
  air-particles, 
  which 
  maintain 
  the 
  pressure, 
  but 
  on 
  

   their 
  proximity 
  (from 
  centre 
  to 
  centre), 
  or 
  on 
  their 
  number 
  in 
  unit 
  of 
  

   volume. 
  Hence, 
  by 
  simple 
  subdivision 
  of 
  the 
  material, 
  we 
  observe 
  that 
  

   any 
  degree 
  of 
  Continuity 
  combined 
  with 
  Vacuity 
  [i. 
  e., 
  optionally 
  small 
  

   collective 
  volume 
  of 
  material 
  compared 
  with 
  the 
  total 
  volume 
  of 
  space 
  

   pervaded] 
  — 
  may 
  be 
  practically 
  achieved, 
  capable 
  of 
  serving 
  useful 
  ends. 
  

   The 
  so-termed 
  tl 
  small 
  " 
  body 
  evidently 
  must 
  not 
  be 
  so 
  reduced 
  that 
  its 
  

   dimensions 
  become 
  comparable 
  to 
  the 
  mean 
  distance 
  [relatively 
  inferior] 
  

   of 
  the 
  component 
  particles 
  of 
  the 
  medium, 
  in 
  which 
  it 
  is 
  located. 
  

  

  