﻿140 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  As 
  a 
  consequence 
  of 
  (2) 
  it 
  is 
  clear 
  that 
  a 
  heavy 
  rainfall 
  on 
  the 
  

   last 
  days 
  of 
  any 
  month 
  may 
  not 
  appear 
  at 
  the 
  point 
  of 
  gaging 
  

   until 
  the 
  next 
  month. 
  Mr 
  Symons 
  also 
  states 
  that 
  the 
  one 
  great 
  

   fact 
  which 
  has 
  been 
  impressed 
  upon 
  him 
  by 
  these 
  investigations 
  

   is 
  the 
  effect 
  of 
  winter 
  frosts 
  in 
  regulating 
  the 
  flow 
  of 
  the 
  river 
  

   Thames 
  and 
  in 
  mitigating 
  winter 
  floods. 
  

  

  These 
  conclusions 
  are 
  more 
  specially 
  intended 
  to 
  apply 
  to 
  the 
  

   river 
  Thames. 
  Hence, 
  while 
  it 
  is 
  true 
  that 
  so-called 
  negative 
  

   evaporation 
  exists 
  on 
  all 
  of 
  the 
  streams 
  considered, 
  the 
  condi- 
  

   tions 
  are 
  nevertheless 
  very 
  different, 
  and 
  in 
  the 
  United 
  States 
  the 
  

   effect 
  of 
  holding 
  back 
  the 
  flow 
  of 
  streams 
  by 
  frosts 
  is 
  in 
  very 
  many 
  

   cases 
  to 
  precipitate 
  a 
  flood 
  of 
  water 
  later 
  on. 
  This 
  element 
  

   would 
  hardly 
  be 
  considered 
  with 
  us 
  as 
  either 
  a 
  river 
  regulator 
  or 
  

   as 
  mitigating 
  floods. 
  1 
  

  

  Evaporation 
  at 
  Ogdensburg. 
  Observations 
  of 
  the 
  amount 
  of 
  

   evaporation 
  from 
  water 
  surfaces 
  in 
  New 
  York 
  were 
  made 
  by 
  

   Prof. 
  James 
  'Coffin, 
  Principal 
  of 
  Ogdensburg 
  Academy, 
  in 
  1838. 
  

   The 
  folloAving 
  are 
  Professor 
  Coffin's 
  results 
  for 
  the 
  year 
  1838, 
  as 
  

   taken 
  from 
  the 
  Regents' 
  reports 
  for 
  1839 
  : 
  

  

  Rainfall, 
  

   Month 
  inches 
  

  

  January 
  2.36 
  

  

  February 
  . 
  97 
  

  

  March 
  1.18 
  

  

  April 
  '. 
  0.40 
  

  

  May 
  4.81 
  

  

  June 
  3.57 
  

  

  July 
  1.88 
  

  

  August 
  2 
  . 
  55 
  

  

  September 
  1 
  . 
  01 
  

  

  October 
  2.73 
  

  

  November 
  2.07 
  

  

  December 
  1 
  . 
  08 
  

  

  Evapora- 
  

   tion, 
  

   inches 
  

  

  Mean 
  

   temperature 
  

  

  1.65 
  

  

  24.8 
  

  

  0.82 
  

  

  12.3 
  

  

  2.07 
  

  

  32.9 
  

  

  1.62 
  

  

  39.8 
  

  

  7.10 
  

  

  52.5 
  

  

  6.75 
  

  

  66.5 
  

  

  7.79 
  

  

  71.7 
  

  

  5.42 
  

  

  68.3 
  

  

  7.40 
  

  

  59.2 
  

  

  3.95 
  

  

  44.6 
  

  

  3.66 
  

  

  29.7 
  

  

  1.15 
  

  

  19.4 
  

  

  Total 
  24.61 
  49.36 
  43.5 
  

  

  Negative 
  evaporation 
  is 
  discussed 
  somewhat 
  more 
  extensively 
  in 
  the 
  

   writer's 
  paper, 
  The 
  Relation 
  of 
  Rainfall 
  to 
  Runoff, 
  than 
  it 
  is 
  here. 
  

  

  