﻿PHYSICAL 
  GEOGRAPHY. 
  27 
  

  

  with 
  a 
  surface 
  slope 
  of 
  between 
  3 
  and 
  3^ 
  inches 
  per 
  mile, 
  and 
  a 
  mean 
  

   velocity 
  of 
  3*90 
  miles 
  per 
  hour. 
  When 
  the 
  discharge 
  at 
  Prome 
  reaches 
  

   1,182,000 
  cubic 
  feet, 
  the 
  permanent 
  banks 
  of 
  the 
  river 
  opposite 
  

   Myanoung 
  begin 
  to 
  be 
  capped 
  by 
  the 
  flood, 
  which 
  finds 
  its 
  way 
  across 
  

   country 
  into 
  the 
  Myit-ma-kha 
  stream, 
  submerging 
  vast 
  tracts 
  at 
  the 
  

   head 
  of 
  the 
  delta, 
  and 
  in 
  this 
  district, 
  it 
  is 
  not 
  uncommon 
  for 
  horses 
  

   and 
  cattle 
  to 
  be 
  penned 
  in 
  dwelling 
  houses 
  built 
  on 
  supports, 
  having 
  

   several 
  feet 
  of 
  water 
  under 
  them, 
  and 
  for 
  two 
  or 
  three 
  months 
  only 
  

   approachable 
  by 
  boats. 
  

  

  The 
  above 
  description 
  of 
  the 
  Irrawadi 
  may 
  not 
  exactly 
  suit 
  the 
  

   views 
  of 
  those 
  who 
  would 
  divide 
  all 
  rivers 
  into 
  either 
  excavating 
  rivers 
  

   or 
  depositing 
  rivers, 
  but 
  if 
  facts 
  interfere 
  inconveniently 
  with 
  theory, 
  

   so 
  much 
  the 
  worse 
  for 
  theory. 
  As 
  a 
  matter 
  of 
  fact, 
  the 
  Irrawadi 
  has 
  

   carved 
  for 
  itself 
  a 
  passage, 
  adequate 
  for 
  its 
  ordinary 
  discharge, 
  but 
  

   inadequate 
  for 
  an 
  extraordinary 
  one. 
  I 
  presume 
  some 
  such 
  period 
  

   must 
  have 
  been 
  passed 
  through 
  by 
  all 
  rivers, 
  which 
  have 
  by 
  slow 
  decrees 
  

   excavated 
  their 
  own 
  channel 
  ; 
  and 
  to 
  my 
  mind 
  it 
  seems 
  the 
  most 
  natural 
  

   thing 
  possible, 
  though 
  it 
  may 
  necessitate 
  our 
  classing 
  the 
  river 
  so 
  

   situated 
  as 
  an 
  excavating 
  one 
  at 
  one 
  period 
  of 
  the 
  year 
  and 
  a 
  deposit- 
  

   ing 
  one 
  at 
  another. 
  Indeed 
  so 
  far 
  as 
  the 
  river 
  is 
  itself 
  concerned, 
  and 
  

   apart 
  from 
  all 
  elevatory 
  movements, 
  a 
  river 
  can 
  only 
  be 
  termed 
  an 
  

   excavating 
  one 
  (save 
  in 
  the 
  most 
  passive 
  of 
  all 
  passive 
  senses) 
  when 
  it 
  

   periodically, 
  is 
  a 
  depositing 
  one 
  also, 
  that 
  is, 
  when 
  its 
  channel 
  is 
  insuffi- 
  

   cient 
  for 
  occasional 
  floods, 
  which 
  create 
  a 
  spill 
  over 
  its 
  banks, 
  and 
  

   deposit 
  silt. 
  Till 
  this 
  ceases 
  to 
  occur, 
  the 
  river 
  is 
  still 
  engaged 
  in 
  

   enlarging 
  its 
  channel, 
  the 
  ultimate 
  efforts, 
  like 
  that 
  of 
  a 
  balance 
  seeking 
  

   equilibrium, 
  being 
  necessarily 
  slow 
  ; 
  but 
  for 
  my 
  part 
  I 
  see 
  little 
  gain 
  in 
  

   any 
  hard 
  and 
  dry 
  classification 
  of 
  rivers 
  into 
  these 
  two 
  classes, 
  or 
  

   attempting 
  to 
  draw 
  a 
  more 
  rigid 
  line 
  than 
  nature 
  does. 
  

  

  The 
  true 
  test 
  of 
  whether 
  a 
  river 
  belongs 
  to 
  the 
  category 
  of 
  exca- 
  

   vating 
  or 
  depositing, 
  depends, 
  not 
  on 
  any 
  process 
  of 
  modification 
  in 
  the 
  

  

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