﻿Hubert 
  Anson 
  Newton. 
  369 
  

  

  inal 
  motion 
  was 
  direct 
  and 
  in 
  an 
  orbit 
  of 
  small 
  inclination 
  to 
  

   that 
  of 
  the 
  planets, 
  and 
  although 
  it 
  may 
  lose 
  a 
  large 
  part 
  of 
  its 
  

   velocity, 
  its 
  motion 
  will 
  generally 
  remain 
  direct 
  and 
  in 
  a 
  plane 
  

   of 
  small 
  inclination. 
  This 
  very 
  interesting 
  case 
  of 
  the 
  comets 
  

   of 
  short 
  periods 
  and 
  small 
  inclinations, 
  which 
  was 
  treated 
  

   rather 
  briefly 
  in 
  this 
  paper, 
  was 
  discussed 
  more 
  fully 
  by 
  Profes- 
  

   sor 
  Newton 
  at 
  the 
  meeting 
  of 
  the 
  British 
  Association 
  in 
  the 
  

   following 
  year.* 
  

  

  Many 
  years 
  later, 
  Professor 
  Newton 
  returned 
  to 
  the 
  same 
  gen- 
  

   eral 
  subject 
  in 
  a 
  very 
  interesting 
  memoir 
  " 
  On 
  the 
  Capture 
  of 
  

   Comets 
  by 
  Planets 
  ; 
  especially 
  their 
  Capture 
  by 
  Jupiter," 
  which 
  

   was 
  read 
  before 
  the 
  National 
  Academy 
  in 
  1891, 
  and 
  appeared 
  

   in 
  the 
  Memoirs 
  of 
  the 
  Academy 
  two 
  years 
  later, 
  f 
  It 
  also 
  

   appeared 
  in 
  this 
  Journal 
  in 
  the 
  year 
  in 
  which 
  it 
  was 
  read.;}: 
  

   This 
  contains 
  the 
  results 
  of 
  careful 
  statistical 
  calculations 
  on 
  

   the 
  effect 
  of 
  perturbations 
  on 
  orbits 
  of 
  comets 
  originally 
  para- 
  

   bolic. 
  It 
  corroborates 
  the 
  more 
  general 
  statements 
  of 
  the 
  

   paper 
  "On 
  the 
  Origin 
  of 
  Comets," 
  giving 
  them 
  a 
  precise 
  quanti- 
  

   tative 
  form. 
  One 
  or 
  two 
  quotations 
  will 
  give 
  some 
  idea 
  of 
  the 
  

   nature 
  of 
  this 
  very 
  elaborate 
  and 
  curious 
  memoir, 
  in 
  which, 
  

   however, 
  the 
  results 
  are 
  largely 
  presented 
  in 
  the 
  form 
  of 
  

   diagrams. 
  

  

  On 
  a 
  certain 
  hypothesis 
  regarding 
  an 
  original 
  equable 
  distri- 
  

   bution 
  of 
  comets 
  in 
  parabolic 
  orbits 
  about 
  the 
  sun, 
  it 
  is 
  shown 
  

   that 
  " 
  if 
  in 
  a 
  given 
  period 
  of 
  time 
  a 
  thousand 
  million 
  comets 
  

   come 
  in 
  parabolic 
  orbits 
  nearer 
  to 
  the 
  sun 
  than 
  Jupiter, 
  126 
  of 
  

   them 
  will 
  have 
  their 
  orbits 
  changed 
  " 
  by 
  the 
  action 
  of 
  that 
  

   planet 
  "into 
  ellipses 
  with 
  periodic 
  times 
  less 
  than 
  one-half 
  that 
  

   of 
  Jupiter 
  ; 
  839 
  of 
  them 
  will 
  have 
  their 
  orbits 
  changed 
  into 
  

   ellipses 
  with 
  periodic 
  times 
  less 
  than 
  that 
  of 
  Jupiter; 
  1701 
  of 
  

   them 
  will 
  have 
  their 
  orbits 
  changed 
  into 
  ellipses 
  with 
  periodic 
  

   times 
  less 
  than 
  once 
  and 
  a 
  half 
  that 
  of 
  Jupiter, 
  and 
  2670 
  of 
  

   them 
  will 
  have 
  their 
  orbits 
  changed 
  into 
  ellipses 
  with 
  periodic 
  

   times 
  less 
  than 
  twice 
  that 
  of 
  Jupiter." 
  A 
  little 
  later, 
  Professor 
  

   Newton 
  considers 
  the 
  question, 
  which 
  he 
  characterizes 
  as 
  per- 
  

   haps 
  more 
  important, 
  of 
  the 
  direct 
  or 
  retrograde 
  motion 
  of 
  the 
  

   comets 
  after 
  such 
  perturbations. 
  It 
  is 
  shown 
  that 
  of 
  the 
  839 
  

   comets 
  which 
  have 
  periodic 
  times 
  less 
  than 
  Jupiter, 
  203 
  will 
  

   have 
  retrograde 
  motions, 
  and 
  636 
  will 
  have 
  direct 
  motions. 
  

   Of 
  the 
  203 
  with 
  retrograde 
  motion, 
  and 
  of 
  the 
  636 
  with 
  direct 
  

   motion, 
  51 
  and 
  257, 
  respectively, 
  will 
  have 
  orbits 
  inclined 
  less 
  

   than 
  30° 
  to 
  that 
  of 
  Jupiter. 
  

  

  We 
  have 
  seen 
  that 
  the 
  earliest 
  of 
  Professor 
  Newton's 
  more 
  

   important 
  studies 
  on 
  meteors 
  related 
  to 
  the 
  Leonids, 
  which 
  at 
  

  

  *Rep'tBrit. 
  Assoc. 
  Adv. 
  Sci. 
  for 
  1819, 
  p. 
  272. 
  

   f 
  Mem. 
  Nat. 
  Acad 
  , 
  vol. 
  vi, 
  1st 
  memoir, 
  

   i 
  This 
  Journal, 
  III, 
  xlii, 
  pp. 
  183 
  and 
  482. 
  

  

  