﻿478 
  Prof. 
  S. 
  R. 
  Cook 
  on 
  

  

  appeared 
  never 
  to 
  come 
  into 
  actual 
  contact, 
  and 
  it 
  was 
  dis- 
  

   tinctly 
  evident 
  that 
  they 
  were 
  not 
  in 
  actual 
  contact 
  in 
  the 
  

   laminae. 
  

  

  I£ 
  only 
  the 
  three 
  forces 
  deduced 
  from 
  the 
  equations 
  of 
  a 
  

   perfect 
  fluid 
  are 
  to 
  be 
  considered, 
  the 
  particles 
  should 
  at 
  

   least 
  be 
  in 
  contact 
  transversely. 
  After 
  a 
  careful 
  study 
  of 
  

   these 
  phenomena 
  it 
  was 
  decided, 
  if 
  possible, 
  to 
  obtain 
  spheres 
  

   small 
  enough 
  and 
  light 
  enough 
  to 
  flute. 
  

  

  III. 
  Forces 
  due 
  to 
  a 
  Flux 
  of 
  a 
  Viscous 
  Fluid 
  around 
  

   Spheres. 
  

  

  The 
  three 
  forces 
  deduced 
  from 
  the 
  theory 
  of 
  a 
  perfect 
  

   fluid 
  have 
  already 
  been 
  discussed, 
  and 
  the 
  experiments 
  have 
  

   pointed 
  to 
  other 
  forces. 
  The 
  presence 
  of 
  these 
  new 
  forces 
  

   will 
  be 
  more 
  clearly 
  manifest 
  in 
  the 
  following 
  experiments 
  

   with 
  spheres 
  in 
  a 
  viscous 
  fluid. 
  

  

  The 
  spheres 
  used 
  were 
  obtained 
  by 
  blowing 
  out 
  from 
  a 
  

   glass 
  tube 
  melted 
  sealing-wax, 
  and 
  allowing 
  the 
  hot 
  spray 
  to 
  

   filter 
  through 
  the 
  air 
  into 
  a 
  vessel 
  of 
  water. 
  In 
  this 
  manner 
  

   a 
  large 
  number 
  of 
  variously-sized 
  spheres 
  could 
  be 
  quickly 
  

   and 
  easily 
  obtained. 
  The 
  spheres, 
  when 
  placed 
  under 
  a 
  

   microscope, 
  were 
  found 
  to 
  be 
  very 
  perfect 
  in 
  form, 
  with 
  

   smooth 
  surfaces, 
  and 
  having 
  a 
  diameter 
  of 
  from 
  0*1 
  to 
  2*0 
  mm. 
  

   When 
  placed 
  in 
  the 
  resonance-tube 
  of 
  the 
  Kunclt 
  apparatus, 
  

   spheres 
  whose 
  diameter 
  was 
  not 
  more 
  than 
  1 
  mm. 
  readily 
  

   formed 
  flirtings. 
  A 
  careful 
  microscopic 
  study 
  was 
  then 
  

   made 
  of 
  attractions 
  and 
  repulsions 
  of 
  these 
  spheres 
  in 
  the 
  

   centre 
  of 
  the 
  ventral 
  segment 
  of 
  a 
  stationary 
  sound-wave, 
  and 
  

   the 
  following 
  observations 
  were 
  determined 
  : 
  — 
  

  

  1. 
  user 
  rations 
  on 
  a 
  Concave 
  Surface. 
  

  

  (1) 
  Spheres 
  whose 
  line 
  of 
  centres 
  was 
  parallel 
  to 
  the 
  

   stream-lines 
  and 
  whose 
  distance 
  apart 
  was 
  greater 
  than 
  

   between 
  one 
  and 
  two 
  tenths 
  of 
  a 
  millimetre 
  repelled. 
  

  

  (2) 
  Spheres 
  whose 
  line 
  of 
  centres 
  was 
  transverse 
  to 
  the 
  

   stream-lines 
  and 
  whose 
  distance 
  apart 
  was 
  greater 
  than 
  

   about 
  half 
  the 
  diameter 
  of 
  the 
  spheres 
  attracted. 
  

  

  (3) 
  Spheres 
  whose 
  line 
  of 
  centres 
  was 
  transverse 
  to 
  the 
  

   stream 
  -lines 
  and 
  whose 
  surfaces, 
  owing 
  to 
  the 
  concavity 
  of 
  

   the 
  tube, 
  were 
  in 
  contact 
  when 
  there 
  was 
  no 
  sound-wave 
  

   present, 
  did 
  not 
  remain 
  in 
  contact 
  when 
  the 
  sound-wave 
  

   obtained 
  but 
  were 
  driven 
  by 
  some 
  repellant 
  force 
  farther 
  up 
  

   the 
  side 
  of 
  the 
  tube. 
  

  

  (4) 
  Spheres 
  whose 
  line 
  of 
  centres 
  was 
  parallel 
  with 
  the 
  

   stream-lines 
  and 
  whose 
  distance 
  was 
  less 
  than 
  half 
  their 
  

  

  