﻿of 
  Matter 
  and 
  Mass. 
  23 
  

  

  attributes 
  o£ 
  matter 
  such 
  as 
  velocity 
  or 
  change 
  of 
  position 
  ? 
  

   The 
  falhicy 
  involved 
  is 
  really 
  a 
  question 
  of 
  definition. 
  

   Accorduig 
  to 
  Newton* 
  the 
  inertia 
  of 
  a 
  body 
  is 
  an 
  inherent 
  

   and 
  inalienable 
  property 
  of 
  it, 
  independent 
  of 
  the 
  influence 
  

   oF 
  any 
  other 
  body 
  or 
  aether, 
  and 
  forms 
  the 
  connecting 
  link 
  

   between 
  ourselves 
  and 
  the 
  external 
  world. 
  The 
  inertia 
  

   referred 
  to 
  by 
  Lewis 
  and 
  other 
  modern 
  writers 
  is 
  a 
  relative 
  

   propertv 
  of 
  matter, 
  depending 
  entirely 
  upon 
  the 
  presence 
  of 
  

   other 
  matter, 
  and 
  has 
  nothing 
  to 
  with 
  the 
  hodij 
  per 
  se. 
  They 
  

   generally 
  take 
  some 
  form 
  of 
  energy 
  as 
  the 
  fundamental 
  

   attribute. 
  But 
  since 
  the 
  absolute 
  nature 
  of 
  matter 
  is 
  entirely 
  

   unknown 
  to 
  us, 
  it 
  seems 
  reasonable 
  to 
  say 
  tliat 
  we 
  have 
  no 
  

   criterion 
  by 
  which 
  we 
  can 
  decide 
  between 
  the 
  two, 
  mass 
  

   and 
  energy. 
  

  

  Undoubtedly 
  those 
  w^ho 
  have 
  maintained 
  the 
  variability 
  of 
  

   inertia 
  of 
  ponderable 
  matter 
  have 
  been 
  obliged 
  to 
  create 
  some 
  

   primitive 
  fluid 
  or 
  aether 
  and 
  supply 
  it 
  with 
  inertia 
  in 
  the 
  

   Newtonian 
  sense. 
  Ponderable 
  matter 
  then 
  becomes 
  merely 
  

   a 
  place 
  of 
  discontinuity 
  or 
  varintion 
  in 
  this 
  primitive 
  fluid, 
  

   which 
  is 
  to 
  be 
  considered 
  the 
  only 
  actual 
  matter. 
  Now 
  to 
  

   transfer 
  the 
  essential 
  properties 
  of 
  a 
  sensible 
  body 
  to 
  another, 
  

   which 
  we 
  have 
  no 
  faculty 
  of 
  detecting 
  directly, 
  is 
  not 
  an 
  

   explanation, 
  but 
  an 
  evasion 
  of 
  the 
  problem. 
  

  

  In 
  any 
  mechanistic 
  theory 
  of 
  phenomena, 
  based 
  on 
  the 
  

   mutual 
  attractions 
  between 
  atoms, 
  the 
  relations 
  between 
  

   mechanics 
  and 
  the 
  other 
  branches 
  of 
  physics 
  are 
  expressed 
  

   in 
  three 
  ways, 
  by 
  hydrodynamic, 
  thermodynamic, 
  or 
  electro- 
  

   dynamic 
  equations. 
  Because 
  of 
  the 
  contradictions 
  which 
  

   have 
  occurred 
  when 
  all 
  j)henomena 
  are 
  explained 
  by 
  forces 
  

   of 
  attraction, 
  the 
  converse 
  problem 
  has 
  been 
  attempted 
  of 
  

   explaining 
  the 
  nature 
  of 
  atoms 
  and 
  their 
  mutual 
  forces, 
  and 
  

   we 
  have 
  as 
  a 
  result 
  Boscovich's 
  centres 
  of 
  force, 
  vortices, 
  

   charges 
  of 
  negative 
  electricity, 
  setherial 
  strains, 
  the 
  "some- 
  

   thing 
  in 
  a 
  beam 
  of 
  radiation/' 
  and 
  others. 
  However 
  diverse 
  

   in 
  appearance, 
  these 
  all 
  have 
  one 
  property 
  in 
  common, 
  they 
  

   deal 
  with 
  a 
  transfer 
  of 
  energy, 
  and 
  they 
  either 
  tacitly 
  or 
  

   openly 
  postulate 
  the 
  existence 
  of 
  invariable 
  inertia 
  in 
  some- 
  

   thing 
  tangible 
  or 
  intangible. 
  

  

  An 
  examination 
  of 
  any 
  one 
  of 
  these 
  will 
  answer 
  the 
  purpose, 
  

   and 
  I 
  have 
  chosen 
  one 
  the 
  least 
  complicated 
  by 
  metaphysical 
  

   abstractions. 
  

  

  If 
  two 
  spheres 
  of 
  radii 
  a 
  and 
  b 
  are 
  immersed 
  in 
  a 
  fluid, 
  

  

  * 
  Princ. 
  Math. 
  Def. 
  III. 
  Usee 
  (materiae 
  vis) 
  semper 
  proportionalis 
  

   est 
  siio 
  corpora, 
  neque 
  differt 
  quicquam 
  ab 
  inertia 
  massse, 
  nisi 
  in 
  modo 
  

   concipiendi. 
  Per 
  inertia 
  m 
  materiae 
  fit, 
  ut 
  corpus 
  omne 
  de 
  statu 
  suo 
  vel 
  

   quiescendi 
  vel 
  movendi 
  difficulter 
  deterbetur. 
  

  

  