﻿BiCKEKTON. 
  — 
  0)1 
  Temporary 
  and 
  Variable 
  Stars. 
  121 
  

  

  the 
  influence 
  of 
  each 
  other's 
  gra'^dtation, 
  they 
  would 
  be 
  attracted 
  out 
  of 
  

   their 
  path 
  with 
  a 
  constantly 
  increasing 
  velocity. 
  Three 
  possibilities 
  present 
  

   themselves 
  : 
  the 
  first, 
  the 
  most 
  general 
  one, 
  of 
  passing 
  each 
  other 
  and 
  

   ultimately 
  attaining 
  their 
  original 
  velocity 
  in 
  space 
  ; 
  the 
  second 
  would 
  

   be 
  that 
  of 
  imperfect 
  im]}act 
  ; 
  and 
  third, 
  as 
  an 
  extreme 
  case, 
  we 
  

   should 
  have 
  complete 
  impact 
  when 
  the 
  centre 
  of 
  each 
  mass 
  would 
  have, 
  

   except 
  for 
  the 
  collision, 
  occupied 
  the 
  same 
  point 
  at 
  the 
  same 
  time. 
  It 
  is 
  

   reasonable 
  to 
  assume 
  that 
  in 
  impact 
  the 
  case 
  of 
  partial 
  collision 
  would 
  be 
  

   more 
  probable 
  than 
  complete 
  impact. 
  And 
  it 
  is 
  this 
  imperfect 
  impact 
  that 
  

   is 
  the 
  basis 
  of 
  the 
  present 
  hj^pothesis. 
  In 
  this 
  case 
  a 
  piece 
  will 
  be 
  struck 
  

   off 
  each 
  colliding 
  body 
  ; 
  these 
  two 
  pieces 
  would 
  to 
  a 
  greater 
  or 
  less 
  degree 
  

   coalesce, 
  developing 
  at 
  the 
  same 
  time 
  a 
  high 
  degree 
  of 
  heat, 
  whilst 
  the 
  

   remainder 
  of 
  the 
  two 
  bodies 
  would 
  pass 
  on 
  in 
  space. 
  What 
  would 
  finally 
  

   happen 
  to 
  the 
  two 
  retreating 
  bodies 
  depends 
  on 
  the 
  original 
  proper 
  motion 
  

   and 
  the 
  masses 
  of 
  the 
  coalesced 
  piece. 
  If 
  the 
  original 
  proper 
  motions 
  were 
  

   large 
  and 
  the 
  piece 
  cut 
  off 
  small, 
  one 
  or 
  both 
  of 
  the 
  two 
  bodies 
  would 
  most 
  

   likely 
  pass 
  entirely 
  away 
  from 
  the 
  other 
  bodies 
  and 
  travel 
  on 
  independently 
  

   in 
  space. 
  If, 
  on 
  the 
  other 
  hand, 
  the 
  original 
  proper 
  motion 
  were 
  small 
  and 
  

   the 
  piece 
  struck 
  off 
  large, 
  then 
  it 
  would 
  be 
  most 
  probable 
  that 
  they 
  would 
  

   be 
  once 
  more 
  attracted 
  back 
  and 
  coUide 
  again 
  and 
  agam 
  until 
  complete 
  

   coalescence 
  took 
  place 
  ; 
  or, 
  as 
  I 
  shall 
  show 
  further, 
  it 
  is 
  possible 
  that 
  they 
  

   may 
  form 
  a 
  system 
  similar 
  to 
  our 
  solar 
  system. 
  The 
  size 
  of 
  the 
  bodies 
  will 
  

   also 
  have 
  an 
  influence 
  in 
  the 
  escape 
  or 
  otherwise 
  of 
  the 
  pieces. 
  Other 
  

   things 
  being 
  equal, 
  the 
  larger 
  the 
  body 
  the 
  greater 
  the 
  probability 
  of 
  escape, 
  

   as 
  the 
  distance 
  between 
  the 
  centres 
  will 
  be 
  greater 
  and 
  consequently 
  the 
  

   attraction 
  will 
  be 
  less. 
  

  

  Partial 
  impact 
  appears 
  competent 
  to 
  explain 
  the 
  occurrence 
  of 
  temporary, 
  

   double, 
  and 
  variable 
  stars, 
  nebulge 
  of 
  various 
  kinds 
  (the 
  kind 
  depending 
  on 
  

   the 
  nature 
  of 
  the 
  impact), 
  comets, 
  and 
  finally 
  stars 
  or 
  suns 
  accompanied 
  by 
  

   bodies 
  of 
  smaller 
  size. 
  The 
  third 
  case, 
  that 
  of 
  complete 
  coalescence, 
  is 
  pro- 
  

   bable 
  only 
  in 
  the 
  collision 
  of 
  very 
  large 
  bodies, 
  and 
  offers 
  an 
  explanation 
  of 
  

   the 
  existence 
  of 
  large 
  spherical 
  nebula 
  with 
  a 
  general 
  condensation 
  towards 
  

   the 
  centre. 
  (We 
  will 
  consider 
  the 
  hypotheses 
  somewhat 
  in 
  detail.) 
  In 
  

   order 
  to 
  render 
  the 
  concex^tion 
  of 
  the 
  hypothesis 
  as 
  simple 
  as 
  possible, 
  I 
  

   shall 
  all 
  through 
  keep 
  as 
  far 
  as 
  I 
  can 
  to 
  a 
  direct 
  conception 
  of 
  energy, 
  as 
  in 
  

   this 
  way 
  most 
  questions 
  may 
  be 
  reduced 
  to 
  ordinary 
  arithmetical 
  series. 
  

   Thus, 
  if 
  the 
  two 
  approaching 
  bodies 
  be 
  equal 
  to 
  each 
  other 
  (at 
  the 
  same 
  

   distance), 
  the 
  attracting 
  force 
  acting 
  on 
  each 
  unit 
  of 
  mass 
  will 
  be 
  propor- 
  

   tional 
  to 
  the 
  total 
  mass 
  of 
  either 
  ; 
  now 
  in 
  a 
  force 
  acting 
  through 
  space, 
  the 
  

   work 
  equals 
  the 
  force 
  multiphed 
  by 
  the 
  space 
  through 
  which 
  it 
  acts, 
  and 
  the 
  

   work 
  is 
  equal 
  to 
  the 
  heat, 
  

  

  