﻿780 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  was 
  greater 
  than 
  2 
  feet. 
  A 
  series 
  of 
  experiments 
  was 
  accord- 
  

   ingly 
  made 
  at 
  Cornell 
  University, 
  extending 
  the 
  results 
  up 
  to 
  6 
  

   feet. 
  

  

  Bridges. 
  The 
  railway 
  and 
  highway 
  bridges 
  were 
  designed 
  for 
  

   250 
  feet 
  clear 
  span 
  on 
  the 
  30-foot 
  channel 
  and 
  240 
  feet 
  on 
  the 
  21- 
  

   foot. 
  In 
  a 
  few 
  cases 
  of 
  highway 
  crossings 
  steam 
  ferries 
  were 
  

   provided 
  for 
  instead 
  of 
  bridges. 
  

  

  Unit 
  prices. 
  In 
  establishing 
  unit 
  prices 
  for 
  the 
  estimates 
  the 
  

   prices 
  paid 
  on 
  large 
  works 
  throughout 
  the 
  country, 
  involving 
  

   similar 
  constructions, 
  were 
  considered 
  and 
  the 
  advice 
  and 
  opinion 
  

   of 
  most 
  of 
  the 
  experienced 
  contracting 
  engineers 
  was 
  secured. 
  

  

  Control 
  of 
  Lake 
  Erie. 
  Under 
  the 
  influence 
  of 
  varying 
  supply, 
  

   evaporation 
  and 
  discharge, 
  the 
  monthly 
  mean 
  level 
  of 
  Lake 
  Erie 
  

   has 
  varied 
  4.6 
  feet 
  during 
  the 
  past 
  seventy 
  years. 
  The 
  low 
  level 
  

  

  "^A, 
  

  

  

  '■&*%& 
  '^^%.^j%x^r-. 
  \rock 
  %{J?$i&.*?'<£fc^M<£&3*>** 
  

   Fig. 
  60 
  Eock 
  cross-section 
  of 
  proposed 
  Barge 
  canal. 
  

  

  occurs 
  from 
  September 
  to 
  November, 
  when 
  navigation 
  is 
  the 
  most 
  

   active. 
  In 
  order 
  to 
  maintain 
  the 
  level 
  the 
  discharge 
  must 
  be 
  so 
  

   controlled 
  that 
  it 
  will 
  always 
  be 
  approximately 
  equal 
  to 
  the 
  dif- 
  

   ference 
  between 
  the 
  water 
  supply 
  and 
  the 
  evaporation 
  of 
  Lake 
  

   Erie. 
  This 
  can 
  be 
  accomplished 
  by 
  establishing 
  regulating 
  works 
  

   at 
  Buffalo. 
  They 
  must 
  be 
  so 
  arranged 
  that 
  they 
  will 
  not 
  only 
  

   maintain 
  the 
  level 
  of 
  the 
  lake 
  at 
  or 
  near 
  the 
  fixed 
  stage 
  adopted, 
  

   but 
  will 
  also 
  produce 
  no 
  injurious 
  effect 
  upon 
  the 
  lakes 
  and 
  water- 
  

   ways 
  from 
  which 
  the 
  supply 
  is 
  derived, 
  or 
  upon 
  those 
  receiving 
  

   the 
  discharge. 
  This 
  problem 
  was 
  investigated 
  by 
  the 
  Board 
  of 
  

   Engineers, 
  and 
  they 
  concluded 
  that 
  the 
  best 
  location 
  for 
  the 
  regu- 
  

   lating 
  works 
  would 
  be 
  at 
  the 
  foot 
  of 
  the 
  lake, 
  just 
  below 
  Buffalo 
  

   harbor. 
  The 
  board 
  also 
  concluded 
  that 
  the 
  level 
  of 
  the 
  lake 
  could 
  

   be 
  maintained 
  during 
  the 
  season 
  of 
  navigation 
  within 
  about 
  0.6 
  

   foot 
  below 
  the 
  level 
  adopted 
  for 
  regulation, 
  under 
  all 
  the 
  condi- 
  

   tions 
  of 
  supply. 
  Variations 
  of 
  level, 
  due 
  to 
  violent 
  winds, 
  will 
  

  

  