﻿98 
  Prof. 
  Sudhansukumar 
  Banerji 
  on 
  Aerial 
  

  

  " 
  the 
  ballistic 
  phonometer 
  *." 
  The 
  intensity 
  was 
  found 
  to 
  

   be 
  a 
  maximum 
  along 
  the 
  line 
  of 
  collision, 
  falling 
  off 
  gradu- 
  

   ally 
  in 
  other 
  directions 
  to 
  a 
  value 
  which 
  is 
  practically 
  zero 
  

   on 
  the 
  surface 
  of 
  a 
  cone 
  of 
  semi-vertical 
  angle 
  67°, 
  and 
  

   rising 
  again 
  to 
  a 
  second 
  but 
  feebler 
  maximum 
  in 
  a 
  plane 
  at 
  

   right 
  angles 
  to 
  the 
  line 
  of 
  collision. 
  

  

  In 
  view 
  of 
  the 
  interesting 
  results 
  obtained 
  for 
  the 
  case 
  of 
  

   two 
  equal 
  spheres, 
  it 
  was 
  arranged 
  to 
  continue 
  the 
  investiga- 
  

   tion 
  and 
  to 
  measure 
  the 
  distribution 
  of 
  intensity 
  when 
  the 
  

   colliding 
  spheres 
  were 
  not 
  both 
  of 
  the 
  same 
  radius 
  or 
  material. 
  

   A 
  mathematical 
  investigation 
  of 
  the 
  nature 
  of 
  the 
  results 
  to 
  

   be 
  expected 
  in 
  these 
  cases 
  was 
  also 
  undertaken. 
  In 
  order 
  

   to 
  exhibit 
  the 
  results 
  of 
  the 
  measurements 
  and 
  of 
  the 
  

   theoretical 
  calculation, 
  a 
  plan 
  has 
  now 
  been 
  adopted 
  which 
  

   is 
  much 
  more 
  suitable 
  than 
  the 
  one 
  used 
  in 
  the 
  first 
  paper. 
  

   This 
  will 
  be 
  best 
  understood 
  by 
  reference 
  to 
  fig. 
  1 
  (PL 
  IV.), 
  

   which 
  refers 
  to 
  the 
  case 
  of 
  two 
  spheres 
  of 
  the 
  same 
  material 
  

   and 
  diameter. 
  The 
  figure 
  has 
  been 
  drawn 
  by 
  taking 
  the 
  point 
  

   at 
  which 
  the 
  spheres 
  impinge 
  as 
  origin, 
  and 
  the 
  line 
  of 
  

   collision 
  as 
  the 
  axis 
  of 
  a, 
  and 
  setting 
  off 
  the 
  indications 
  of 
  

   the 
  ballistic 
  phonometer 
  as 
  radii 
  vectores 
  at 
  the 
  respective 
  

   angles 
  which 
  the 
  directions 
  in 
  which 
  the 
  sound 
  is 
  measured 
  

   make 
  with 
  the 
  line 
  of 
  collision. 
  The 
  curve 
  thus 
  represents 
  

   the 
  distribution 
  of 
  intensity 
  round 
  the 
  colliding 
  spheres 
  in 
  

   polar 
  coordinates, 
  the 
  points 
  at 
  which 
  the 
  intensity 
  of 
  the 
  

   sound 
  is 
  measured 
  being 
  assumed 
  to 
  be 
  all 
  at 
  the 
  same 
  

   distance 
  from 
  the 
  spheres. 
  The 
  results 
  are 
  brought 
  much 
  

   more 
  vividly 
  before 
  the 
  eye 
  by 
  a 
  diagram 
  of 
  this 
  kind 
  than 
  

   by 
  plotting 
  the 
  results 
  on 
  squared 
  paper. 
  

  

  2. 
  Case 
  of 
  two 
  spheres 
  of 
  the 
  same 
  material 
  but 
  of 
  

   different 
  diameters. 
  

  

  Fig. 
  2, 
  which 
  shows 
  the 
  observed 
  distribution 
  of 
  intensity 
  

   when 
  two 
  spheres 
  of 
  wood 
  of 
  diameters 
  3 
  inches 
  and 
  2£ 
  

   inches 
  collide 
  with 
  each 
  other, 
  is 
  typical 
  of 
  the 
  results 
  

   obtained 
  when 
  the 
  impinging 
  spheres 
  are 
  nearly 
  of 
  the 
  same 
  

   density 
  and 
  are 
  of 
  different 
  diameters. 
  There 
  is 
  a 
  distinct 
  

   asymmetry 
  about 
  a 
  plane 
  perpendicular 
  to 
  the 
  line 
  of 
  impact. 
  

   In 
  addition 
  to 
  the 
  maxima 
  of 
  intensity 
  in 
  the 
  two 
  direc- 
  

   tions 
  ol 
  the 
  line 
  of 
  collision, 
  we 
  have 
  the 
  maxima 
  in 
  lateral 
  

   directions, 
  which 
  are 
  not 
  at 
  right 
  angles 
  to 
  this 
  line. 
  The 
  

  

  * 
  This 
  name 
  was 
  suggested 
  by 
  Prof. 
  E. 
  H. 
  Barton, 
  D.Sc, 
  F.R.S., 
  

   writing 
  in 
  the 
  'Science 
  Abstracts/ 
  p. 
  399, 
  Sept. 
  1916. 
  

  

  