﻿316 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  123,330 
  cubic 
  feet 
  per 
  second 
  instead 
  of 
  265,000 
  cubic 
  feet 
  per 
  

   second, 
  as 
  determined 
  by 
  the 
  Lake 
  Survey. 
  These 
  figures, 
  white 
  

   not 
  conclusive, 
  are 
  (Suggestive, 
  so 
  much 
  so, 
  indeed, 
  that 
  taking 
  into 
  

   account 
  all 
  the 
  conditions 
  it 
  seems 
  clear 
  that 
  in 
  a 
  series 
  of 
  years 
  of 
  

   minimum 
  rainfall 
  the 
  runoff 
  of 
  the 
  Great 
  Lakes, 
  tributary 
  to 
  

   Niagara 
  river, 
  may 
  be 
  as 
  low 
  as 
  from 
  6 
  to 
  9 
  inches 
  a 
  year 
  on 
  the 
  

   catchment. 
  At 
  the 
  former 
  figure 
  the 
  measn 
  discharge 
  would 
  be 
  

   about 
  177,700 
  cubic 
  feet 
  per 
  second. 
  1 
  

  

  As 
  an 
  additional 
  source 
  of 
  loss 
  from 
  the 
  Great 
  Lakes 
  the 
  diver- 
  

   sion) 
  of 
  10,000 
  cubic 
  feet 
  per 
  second 
  through 
  the 
  Chicago 
  drainage 
  

   canal 
  to 
  the 
  headwaters 
  of 
  Illinois 
  river 
  may 
  be 
  referred 
  tov 
  

   Thus 
  far 
  the 
  discussion 
  of 
  such 
  loss 
  has 
  been 
  mainly 
  conducted 
  

   on 
  the 
  supposition 
  that 
  the 
  mean 
  discharge 
  of 
  the 
  Great 
  Lakes 
  at 
  

   Niagara 
  was 
  about 
  265,000 
  cubic 
  feet 
  per 
  second. 
  If 
  this 
  were 
  

   true 
  the 
  injurious 
  effect 
  of 
  such 
  diversion 
  could 
  only 
  appear 
  dur- 
  

   ing 
  a 
  series 
  of 
  extremely 
  dry 
  years. 
  The 
  writer 
  can 
  not 
  but 
  think 
  

   that 
  this 
  whole 
  question 
  of 
  the 
  runoff 
  of 
  Niagara 
  river 
  has 
  become 
  

   fogged 
  by 
  a 
  discussion 
  based 
  thus 
  far 
  purely 
  on 
  averages. 
  What 
  

   we 
  really 
  want 
  to 
  know 
  is 
  the 
  runoff 
  of 
  a 
  cycle 
  of 
  dry 
  years. 
  With 
  

   such 
  data 
  we 
  can 
  compute 
  the 
  effect 
  of 
  a 
  given 
  diversion 
  more 
  

   satisfactorily 
  than 
  when 
  dealing 
  with 
  means. 
  

  

  With 
  a 
  cycle 
  of 
  rainfall 
  years, 
  either 
  high 
  or 
  about 
  the 
  average 
  

   very 
  little 
  effect 
  from 
  such 
  diversion 
  will 
  be 
  observed, 
  the 
  con- 
  

   sensus 
  of 
  opinion 
  at 
  the 
  present 
  time 
  apparently 
  being 
  that 
  it 
  will 
  

   not 
  exceed 
  about 
  0.3 
  to 
  0.4 
  foot 
  in 
  depth 
  over 
  the 
  areas 
  affected. 
  

   Owing 
  to 
  the 
  balancing 
  of 
  conditions 
  due 
  to 
  the 
  pondage 
  of 
  the 
  

   Great 
  Lakes, 
  and 
  which 
  require® 
  years 
  in 
  order 
  to 
  complete 
  a 
  

   cycle, 
  it 
  is 
  uncertain 
  whether 
  the 
  abstraction 
  of 
  10,000 
  cubic 
  feet 
  

   per 
  second 
  at 
  Chicago 
  would 
  be 
  specially 
  detrimental 
  at 
  Niagara 
  

  

  *By 
  way 
  of 
  illustrating 
  further 
  the 
  probable 
  inaccuracy 
  of 
  the 
  Lake 
  Survey 
  

   figures, 
  it 
  may 
  be 
  pointed 
  out 
  that 
  if 
  the 
  determination 
  of 
  evaporation 
  from 
  

   the 
  water 
  surfaces 
  at 
  101,890 
  cubic 
  feet 
  per 
  second 
  and 
  runoff 
  at 
  265,000- 
  

   cubic 
  feet 
  per 
  second 
  for 
  the 
  year 
  1868 
  is 
  correct, 
  the 
  total 
  outgo 
  from 
  these 
  

   two 
  sources 
  was 
  368,890' 
  cubic 
  feet 
  per 
  second, 
  leaving 
  the 
  land 
  evaporation 
  

   for 
  that 
  year 
  at 
  156,330 
  cubic 
  feet 
  per 
  second, 
  or 
  at 
  0.9 
  foot 
  over 
  the 
  

   catchment. 
  

  

  By 
  studying 
  the 
  evaporation 
  of 
  the 
  Upper 
  Mississippi 
  reservoirs, 
  the 
  

   Desplaines 
  and 
  Muskingum 
  rivers, 
  and 
  other 
  streams 
  herein 
  referred 
  to 
  r 
  

   it 
  will 
  readily 
  be 
  seen 
  that 
  it 
  is 
  exceedingly 
  improbable 
  that 
  a 
  land 
  evapo- 
  

   ration 
  as 
  low 
  as 
  0.9 
  foot 
  ever 
  occurred 
  over 
  the 
  whole 
  catchment 
  of 
  the 
  

   Great 
  Lakes. 
  

  

  