﻿HYDROLOGY 
  OF 
  NEW 
  YORK 
  121 
  

  

  ant 
  in 
  estimating 
  the 
  permanency 
  of 
  a 
  stream. 
  Aside 
  from 
  Mr 
  

   Vermeule's, 
  the 
  most 
  satisfactory 
  discussion 
  which 
  the 
  writer 
  

   has 
  seen 
  is 
  that 
  of 
  Mr 
  W. 
  S. 
  Auchincloss. 
  1 
  This 
  paper, 
  while 
  too 
  

   long 
  to 
  be 
  abstracted, 
  is 
  nevertheless 
  very 
  interesting, 
  because 
  the 
  

   author 
  recognizes 
  the 
  limitations 
  of 
  averages. 
  On 
  page 
  10, 
  after 
  

   giving 
  a 
  table 
  of 
  the 
  average 
  rise 
  of 
  his 
  sublake, 
  he 
  states 
  : 
  

  

  Since 
  the 
  table 
  was 
  built 
  up 
  from 
  averages, 
  we 
  must 
  not 
  expect 
  

   it 
  -to 
  emphasize 
  special 
  variations, 
  for 
  the 
  grouping 
  of 
  averages 
  

   resembles 
  the 
  grouping 
  of 
  pictures 
  in 
  composite 
  photography. 
  

   The 
  combination 
  invariably 
  brings 
  out 
  class 
  likenesses 
  to 
  the 
  

   exclusion 
  of 
  individual 
  features. 
  Thus 
  the 
  table 
  loses 
  sight 
  of 
  an 
  

   extraordinary 
  year 
  like 
  1889 
  — 
  full 
  of 
  plus 
  quantities 
  — 
  also 
  seasons 
  

   of 
  drought, 
  like 
  1894 
  and 
  1895. 
  It, 
  however, 
  clearly 
  shows 
  that 
  

   influx 
  has 
  a 
  tendency 
  to 
  prevail 
  between 
  February 
  and 
  July, 
  in- 
  

   elusive, 
  and 
  efflux 
  to 
  hold 
  the 
  mastery 
  during 
  the 
  remaining 
  

   months 
  of 
  the 
  year. 
  

  

  Though 
  this 
  paper 
  does 
  not 
  fully 
  recognize 
  the 
  wide 
  variation 
  

   occurring 
  in 
  different 
  localities, 
  this 
  is 
  probably 
  not 
  due 
  to 
  over- 
  

   sight, 
  but 
  merely 
  to 
  the 
  fact 
  that 
  the 
  author 
  was 
  discussing 
  a 
  

   specific 
  case. 
  The 
  observations 
  recorded 
  were 
  made 
  at 
  Bryn 
  

   Mawr, 
  Pa. 
  The 
  paper 
  is 
  valuable 
  and 
  well 
  worth 
  the 
  attention 
  of 
  

   students 
  of 
  hydrology. 
  

  

  Vermeule's 
  formulas. 
  These 
  formulas 
  are 
  somewhat 
  different 
  

   from 
  those 
  previously 
  considered. 
  Mr 
  Vermeule 
  claims 
  to 
  have 
  

   discovered 
  a 
  relation 
  between 
  evaporation 
  and 
  mean 
  annual 
  tem- 
  

   perature. 
  For 
  the 
  relation 
  between 
  annual 
  evaporation 
  and 
  

   annual 
  precipitation 
  on 
  Sudbury. 
  Croton 
  and 
  Passaic 
  rivers 
  he 
  

   gives 
  the 
  following 
  : 
  

  

  E 
  = 
  15.50 
  + 
  0.16 
  R, 
  (18) 
  

  

  In 
  which 
  E 
  = 
  the 
  annual 
  evaporation 
  and 
  R 
  = 
  the 
  annual 
  

   rainfall. 
  

  

  In 
  the 
  original 
  publication 
  of 
  this 
  formula, 
  in 
  the 
  Report 
  of 
  the 
  

   Geological 
  Survey 
  of 
  New 
  Jersey, 
  2 
  Mr 
  Vermeule 
  allowed 
  for 
  other 
  

   catchment 
  areas 
  an 
  increase 
  or 
  decrease 
  of 
  5 
  per 
  cent 
  from 
  values 
  

  

  lOn 
  Waters 
  within 
  the 
  Earth 
  and 
  Laws 
  of 
  Rainflow, 
  by 
  W. 
  S. 
  Auchin- 
  

   closs, 
  C. 
  E. 
  Philadelphia, 
  1897. 
  

  

  2 
  Report 
  on 
  Water 
  Supply, 
  Water 
  Power, 
  the 
  Flow 
  of 
  Streams, 
  and 
  

   Attendant 
  Phenomena, 
  by 
  C. 
  C. 
  Vermeule: 
  Final 
  Report 
  State 
  Geologist' 
  of 
  

   New 
  Jersey, 
  Vol. 
  III. 
  Trenton, 
  1894. 
  

  

  