﻿106 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  into 
  the 
  stream, 
  forming 
  surface 
  or 
  flood 
  flows; 
  finally, 
  another 
  

   part 
  sinks 
  into 
  the 
  ground, 
  to 
  replenish 
  the 
  great 
  reservoir 
  from 
  

   which 
  plants 
  are 
  fed 
  and 
  stream 
  flows 
  maintained 
  during 
  the 
  

   periods 
  of 
  slight 
  rainfall, 
  for 
  the 
  rainfall 
  is 
  frequently, 
  for 
  months 
  

   together, 
  much 
  less 
  than 
  the 
  combined 
  demands 
  of 
  evaporation, 
  

   plant 
  growth, 
  and 
  stream 
  flow. 
  These 
  demands 
  are 
  inexorable, 
  

   and 
  it 
  is 
  the 
  ground 
  storage 
  which 
  is 
  called 
  upon 
  to 
  supply 
  them 
  

   when 
  rain 
  fails 
  to 
  do 
  so. 
  

  

  All 
  of 
  these 
  ways 
  of 
  disposing 
  of 
  the 
  rain 
  which 
  falls 
  upon 
  the 
  

   earth 
  may 
  be 
  classed 
  as 
  either 
  evaporation 
  or 
  stream 
  flow. 
  

   Evaporation 
  Ave 
  take 
  to 
  include 
  direct 
  evaporation 
  from 
  the 
  sur- 
  

   face 
  of 
  the 
  earth, 
  or 
  from 
  water 
  surfaces, 
  and 
  also 
  the 
  water 
  

   taken 
  up 
  by 
  vegetation, 
  most 
  of 
  which 
  is 
  transpired 
  as 
  vapor, 
  but 
  

   a 
  portion 
  of 
  which 
  is 
  taken 
  permanently 
  into 
  the 
  organisms 
  of 
  

   the 
  plants. 
  Stream 
  flow 
  includes 
  the 
  water 
  which 
  passes 
  directly 
  

   over 
  the 
  surface 
  to 
  the 
  stream, 
  and 
  also 
  that 
  which 
  is 
  temporarily 
  

   absorbed 
  by 
  the 
  earth 
  to 
  be 
  slowly 
  discharged 
  into 
  the 
  streams. 
  

   A 
  portion, 
  usually 
  extremely 
  small, 
  passes 
  downward 
  into 
  the 
  

   earth 
  and 
  appears 
  neither 
  as 
  evaporation 
  nor 
  as 
  stream 
  flow. 
  It 
  

   is 
  usually 
  too 
  small 
  to 
  be 
  considered, 
  and 
  we 
  may 
  for 
  our 
  purposes 
  

   assume 
  that 
  all 
  of 
  the 
  rain 
  which 
  falls 
  upon 
  a 
  given 
  watershed 
  

   and 
  does 
  not 
  go 
  off 
  as 
  stream 
  flow 
  is 
  evaporated, 
  using 
  the 
  latter 
  

   word 
  in 
  the 
  broadened 
  sense 
  which 
  we 
  have 
  above 
  described. 
  

  

  Probably 
  one 
  very 
  important 
  effect 
  of 
  forests 
  is 
  that 
  upon 
  the 
  

   ground-water 
  flow 
  of 
  streams. 
  The 
  stream 
  with 
  a 
  catchment 
  area 
  

   wholly 
  or 
  largely 
  in 
  forests 
  will 
  show, 
  without 
  exception, 
  a 
  much 
  

   better 
  ground 
  flow 
  than 
  one 
  with 
  the 
  area 
  denuded 
  of 
  forests. 
  

   Neshaminy 
  and 
  Tohickon 
  creeks 
  may 
  be 
  cited 
  as 
  streams 
  with 
  

   the 
  smallest 
  amount 
  of 
  forest 
  and 
  the 
  lowest 
  curve 
  of 
  ground- 
  

   water 
  flow. 
  Possibly 
  this 
  is 
  not 
  entirely 
  due 
  to 
  forests, 
  but 
  it 
  

   may 
  be 
  assumed 
  that 
  they 
  bear 
  some 
  relation 
  to 
  the 
  result. 
  1 
  

  

  Units 
  of 
  measurement. 
  Clemens 
  Herschel, 
  member 
  American 
  

   Society 
  Civil 
  Engineers, 
  in 
  his 
  paper 
  on 
  Measuring 
  Water 
  2 
  has 
  

   defined 
  the 
  essential 
  elements 
  of 
  this 
  question 
  in 
  the 
  following 
  

   terms 
  : 
  

  

  For 
  most 
  purposes 
  the 
  unit 
  of 
  volume, 
  when 
  using 
  English 
  

   measures, 
  has 
  been 
  agreed 
  upon 
  in 
  favor 
  of 
  the 
  cubic 
  foot, 
  and 
  

  

  1 
  Examples 
  of 
  ground-water 
  cm-res 
  for 
  the 
  chief 
  streams 
  therein 
  con- 
  

   sidered 
  may 
  be 
  found 
  in 
  Mr. 
  Verineule's 
  Report 
  on 
  the 
  Flow 
  of 
  Streams, 
  

   etc., 
  in 
  Final 
  Kept'. 
  State 
  Geologist 
  of 
  New 
  Jersey, 
  Vol. 
  III. 
  Trenton, 
  1S94. 
  

  

  2 
  Measuring 
  Water, 
  by 
  Clemens 
  Herschel; 
  An 
  address 
  'to 
  the 
  students 
  of 
  

   Rensselaer 
  Polytechnic 
  Institute, 
  Troy, 
  N. 
  Y. 
  

  

  