﻿86 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Where 
  a? 
  is 
  the 
  unknown 
  special 
  coefficient 
  of 
  deficiency 
  due 
  to 
  

   wind 
  at 
  that 
  altitude 
  — 
  that 
  is 
  to 
  say, 
  having 
  two 
  gage 
  catches, 
  

   c 
  x 
  and 
  c 
  2 
  for 
  the 
  two 
  altitudes, 
  H^ 
  and 
  H 
  2 
  — 
  we 
  obtain 
  the 
  true 
  

   rainfall 
  (R) 
  by 
  the 
  formulas: 
  

  

  c=(l—x\/K) 
  R; 
  and 
  (2) 
  

  

  *=(1— 
  «VH,j 
  R. 
  (3) 
  

  

  whence, 
  

  

  B^, 
  VH.-o, 
  VH 
  1 
  _ 
  +n 
  (er-cX 
  (4) 
  

  

  VH-VH 
  ' 
  /H, 
  , 
  it 
  vi 
  y 
  

  

  Jf 
  ^ 
  and 
  Hj 
  relate 
  to 
  the 
  lower 
  gage, 
  we 
  shall 
  generally 
  have 
  

   c 
  x 
  > 
  r 
  2 
  and 
  H 
  l 
  <H 
  2 
  , 
  and 
  the 
  coefficient 
  n 
  will 
  be 
  a 
  positive 
  fraction, 
  

   for 
  value 
  of 
  which, 
  for 
  such 
  combinations 
  as 
  may 
  easily 
  occur 
  in 
  

   practice, 
  a 
  table 
  is 
  given 
  in 
  the 
  paper. 
  

  

  It 
  is 
  evident 
  then, 
  without 
  special 
  discussion, 
  that 
  nearly 
  all 
  

   rainfall 
  measurements 
  thus 
  far 
  made 
  in 
  the 
  United 
  States 
  are 
  

   only 
  approximations, 
  and 
  that 
  while 
  they 
  remain 
  in 
  this 
  state 
  to 
  

   carry 
  them 
  out 
  to 
  more 
  than 
  one 
  decimal 
  place 
  is 
  an 
  unnecessary 
  

   refinement. 
  

  

  Determination 
  of 
  minimum 
  rainfall. 
  The 
  writer 
  has 
  spent 
  con- 
  

   siderable 
  time 
  in 
  an 
  attempt 
  to 
  determine 
  about 
  what 
  the 
  mini- 
  

   mum 
  rainfall 
  at 
  any 
  particular 
  station 
  may 
  be 
  expected 
  to 
  be; 
  or, 
  

   rather, 
  he 
  has 
  endeavored 
  to 
  ascertain 
  the 
  relation 
  between 
  the 
  

   minimum 
  rainfall 
  and 
  the 
  maximum. 
  In 
  the 
  course 
  of 
  this 
  quest 
  

   he 
  has 
  examined 
  practically 
  all 
  the 
  records 
  in 
  the 
  State 
  of 
  New 
  

   York, 
  as 
  well 
  as 
  many 
  records 
  in 
  New 
  Jersey, 
  Pennsylvania, 
  

   Michigan, 
  Illinois, 
  Nebraska, 
  Colorado, 
  and 
  Wyoming, 
  as 
  well 
  as 
  

   in 
  Canada. 
  As 
  a 
  general 
  rule, 
  to 
  which 
  there 
  are 
  some 
  excep- 
  

   tions, 
  the 
  minimum 
  rainfall 
  may 
  be 
  placed 
  at 
  about 
  one-half 
  of 
  

   the 
  maximum. 
  That 
  is, 
  if 
  the 
  maximum 
  rainfall 
  at 
  a 
  given 
  

   station 
  is 
  about 
  50 
  inches, 
  the 
  minimum 
  will 
  be 
  in 
  the 
  vicinity 
  of 
  

   20 
  to 
  25 
  inches. 
  In 
  some 
  cases 
  the 
  minimum 
  will 
  be 
  not 
  more 
  

   than 
  one-third 
  of 
  the 
  maximum, 
  or 
  even 
  somewhat 
  less 
  than 
  one- 
  

   third; 
  occasionally, 
  not 
  more 
  than 
  one-quarter. 
  It 
  is 
  not 
  in- 
  

   tended, 
  however, 
  to 
  lay 
  this 
  down 
  as 
  an 
  absolutely 
  universal 
  rule, 
  

   but 
  rather, 
  for 
  the 
  present, 
  as 
  a 
  somewhat 
  imperfect 
  guide. 
  As 
  a 
  

  

  