﻿Resistance 
  due 
  to 
  Ohliquely 
  Moving 
  Waves, 
  415 
  

  

  product 
  of 
  two 
  factors, 
  one 
  the 
  pressure 
  acting 
  perpendicularly 
  

   upon 
  the 
  skin 
  of 
  the 
  ship 
  and 
  secondly 
  the 
  sine 
  of 
  the 
  angle 
  (6) 
  

   between 
  the 
  skin 
  and 
  the 
  direction 
  of 
  travel. 
  If, 
  as 
  usual 
  in 
  

   the 
  fore 
  part 
  of 
  a 
  ship, 
  the 
  skin 
  faces 
  everywhere 
  forwards 
  

   so 
  that 
  6 
  is 
  positive, 
  we 
  recognize 
  that 
  if 
  we 
  estimate 
  the 
  

   pressures 
  from 
  the 
  normal 
  condition 
  of 
  rest, 
  there 
  is 
  a 
  force 
  

   ot 
  retardation 
  from 
  the 
  water-surface 
  downwards 
  in 
  the 
  

   region 
  of 
  an 
  elevation, 
  but 
  on 
  the 
  other 
  hand 
  a 
  force 
  of 
  

   acceleration 
  in 
  the 
  region 
  of 
  a 
  depression. 
  And 
  the 
  question 
  

   at 
  once 
  arises 
  whether 
  we 
  cannot, 
  at 
  least 
  in 
  some 
  degree, 
  

   accommodate 
  the 
  angle 
  to 
  the 
  pressure 
  so 
  as 
  to 
  diminish 
  the 
  

   sum 
  total 
  of 
  the 
  fore-and-aft 
  components. 
  In 
  order 
  to 
  attain 
  

   this 
  end 
  it 
  is 
  evident 
  that 
  6 
  should 
  be 
  diminished 
  (perhaps 
  

   even 
  to 
  the 
  extent 
  of 
  becoming 
  negative) 
  in 
  the 
  region 
  of 
  an 
  

   elevation, 
  and 
  should 
  be 
  increased 
  in 
  the 
  region 
  of 
  a 
  

   depression. 
  

  

  Several 
  years 
  ago 
  (I 
  think 
  it 
  was 
  in 
  1902) 
  with 
  the 
  late 
  

   Mr. 
  Gordon, 
  I 
  attempted 
  some 
  experiments 
  in 
  illustration 
  of 
  

   this 
  theory. 
  The 
  water, 
  to 
  a 
  depth 
  of 
  4 
  or 
  5 
  inches, 
  w^as 
  

   contained 
  in 
  large 
  flat 
  sponge-bath 
  mounted 
  upon 
  a 
  turn- 
  

   table 
  and 
  maintained 
  in 
  uniform 
  rotation. 
  N^ear 
  the 
  circum- 
  

   ference 
  the 
  revolving 
  water 
  flowed 
  past 
  a 
  fixed 
  model 
  which 
  

   represented 
  the 
  ship. 
  The 
  model 
  was 
  of 
  wood 
  with 
  vertical 
  

   sides 
  and 
  flat 
  bottom, 
  and 
  was 
  curved 
  along 
  its 
  length 
  in 
  

   conformity 
  with 
  the 
  circular 
  motion 
  of 
  the 
  water. 
  No 
  attempt 
  

   was 
  made 
  to 
  measure 
  the 
  forces 
  of 
  resistance, 
  but 
  observations 
  

   were 
  taken 
  of 
  the 
  wave-pattern 
  as 
  affected 
  by 
  changes 
  in 
  the 
  

   form 
  of 
  the 
  bow\ 
  Starting 
  from 
  a 
  somewhat 
  blunt 
  figure, 
  

   the 
  wood 
  was 
  gradually 
  cut 
  away 
  from 
  the 
  rear 
  of 
  the 
  region 
  

   of 
  the 
  waves 
  o£ 
  elevation, 
  thus 
  for 
  one 
  thing 
  sharpening 
  the 
  

   bow, 
  care 
  being 
  taken 
  not 
  to 
  continue 
  this 
  operation 
  into 
  the 
  

   rear 
  of 
  the 
  region 
  of 
  the 
  waves 
  of 
  depression. 
  In 
  this 
  way 
  

   wath 
  frequent 
  trials 
  verifying 
  the 
  actual 
  positions 
  of 
  the 
  waves 
  

   at 
  the 
  various 
  stages, 
  an 
  undulating 
  form 
  with 
  vertical 
  sides, 
  

   and 
  (it 
  must 
  be 
  admitted) 
  o£ 
  unprepossessing 
  appearance, 
  was 
  

   gradually 
  developed, 
  which 
  seemed 
  to 
  have 
  the 
  property 
  of 
  

   originating 
  a 
  much 
  less 
  pronounced 
  wave-system, 
  with 
  

   promise 
  o£ 
  a 
  diminished 
  resistance. 
  

  

  So 
  far 
  as 
  these 
  experiments 
  went, 
  they 
  tended 
  to 
  confirm 
  

   me 
  in 
  the 
  idea 
  that 
  advantage 
  might 
  arise 
  from 
  a 
  similar 
  

   figuring 
  of 
  an 
  actual 
  ship, 
  but 
  it 
  was 
  evident 
  that 
  much 
  better 
  

   trials 
  upon 
  models 
  in 
  a 
  suitable 
  tank 
  was 
  the 
  next 
  step, 
  and 
  

   my 
  object 
  in 
  writing 
  the 
  present 
  note 
  is 
  to 
  suggest 
  the 
  

   execution 
  of 
  such 
  trials. 
  The 
  natural 
  course 
  would 
  be 
  to 
  

   start 
  from 
  a 
  paraffin 
  model 
  of 
  an 
  actual 
  ship, 
  and 
  after 
  

  

  