﻿126 
  REPORT 
  UNITED 
  STATES 
  , 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  this 
  shows 
  that 
  the 
  difference 
  between 
  the 
  highest 
  and 
  lowest 
  mean 
  for 
  

   January 
  in 
  the 
  series 
  of 
  years 
  was 
  24°.2. 
  By 
  reference 
  to 
  the 
  Brecken- 
  

   ridge 
  record 
  in 
  Table 
  VI 
  it 
  will 
  be 
  seen 
  that 
  the 
  lowest 
  January 
  mean 
  was 
  

   in 
  1875 
  ( 
  —9° 
  5), 
  while 
  the 
  highest 
  was 
  in 
  1878 
  (+14°.7) 
  j 
  the 
  difference 
  be- 
  

   tween 
  these 
  two 
  is 
  24P.2, 
  as 
  given 
  in 
  the 
  above 
  table 
  of 
  extreme 
  varia. 
  

   tion 
  of 
  monthly 
  means. 
  The 
  right-hand 
  column 
  shows 
  the 
  average 
  of 
  

   all 
  the 
  stations 
  for 
  each 
  month. 
  

  

  The 
  value 
  of 
  this 
  table 
  consists 
  in 
  the 
  fact 
  that 
  it 
  shows 
  at 
  a 
  glance 
  

   the 
  months 
  in 
  which 
  the 
  greatest 
  variations 
  occur. 
  This 
  is, 
  as 
  is 
  well 
  

   known 
  to 
  all 
  who 
  have 
  made 
  meteorology 
  a 
  study, 
  in 
  the 
  winter 
  half 
  of 
  

   the 
  year 
  ; 
  but 
  reference 
  to 
  the 
  column 
  of 
  averages 
  shows 
  that 
  in 
  the 
  

   West 
  and 
  Northwest 
  this 
  is 
  true 
  to 
  an 
  unusual 
  degree, 
  the 
  average 
  varia- 
  

   tion 
  for 
  the 
  winter 
  half 
  (from 
  November 
  to 
  April) 
  being 
  16°.8, 
  while 
  for 
  

   the 
  summer 
  half 
  (from 
  May 
  to 
  October) 
  it 
  is 
  only 
  6°.6. 
  

  

  If 
  we 
  confine 
  the 
  examination 
  to 
  the 
  northwestern 
  stations, 
  Breck- 
  

   enridge, 
  Fort 
  Sully, 
  Yankton, 
  Fort 
  Benton, 
  Pembina, 
  Virginia 
  City, 
  

   -and 
  Bismarck, 
  we 
  find 
  the 
  averages 
  to 
  be 
  as 
  follows 
  : 
  January, 
  21°.9 
  ; 
  

   February, 
  24°.7; 
  March, 
  23°.3; 
  April, 
  9°.9; 
  May, 
  7°.8; 
  June, 
  7°.l; 
  

   July, 
  5°.5; 
  August, 
  4°.5; 
  September, 
  7°.6j 
  October, 
  7°.0; 
  November, 
  

   11°.9; 
  December, 
  22°. 
  7 
  ; 
  the 
  average 
  of 
  the 
  winter 
  half 
  of 
  the 
  year, 
  

   19°.l, 
  and 
  of 
  the 
  summer 
  half, 
  6°. 
  6, 
  showing 
  the 
  difference 
  to 
  be 
  still 
  

   greater. 
  

  

  But 
  in 
  order 
  to 
  apply 
  the 
  law 
  which 
  these 
  figures 
  ^appear 
  to 
  indicate 
  

   more 
  directly 
  to 
  the 
  subject 
  under 
  discussion, 
  we 
  present 
  here 
  a 
  table 
  of 
  

   a 
  similar 
  kind, 
  made 
  up 
  from 
  the 
  same 
  series 
  of 
  years, 
  differing 
  from 
  the 
  

   last 
  only 
  in 
  the 
  fact 
  that 
  it 
  shows 
  the 
  greatest 
  variation 
  between 
  the 
  

   monthly 
  means 
  of 
  two 
  consecutive 
  years. 
  

  

  Table 
  IX. 
  — 
  Greatest 
  variations 
  between 
  monthly 
  means 
  of 
  two 
  consecutive 
  years. 
  

  

  

  be 
  

  

  

  

  

  

  

  -d 
  

  

  

  

  

  p 
  

  

  

  

  

  

  Months. 
  

  

  1 
  

  

  g 
  

  

  02 
  

  

  +3 
  

  

  f-i 
  

  

  o 
  

  

  1 
  

   1 
  

  

  a 
  

  

  a 
  

   1 
  

  

  0> 
  

  

  03 
  

  

  Oh 
  

   a 
  

  

  8 
  

  

  $ 
  

   03 
  

  

  o 
  

  

  a 
  

   a 
  

   g 
  

  

  

  3 
  

  

  § 
  

  

  ■PQ 
  

  

  © 
  

  

  g 
  

  

  a 
  

  

  5 
  

   '3 
  

  

  •a 
  

  

  i 
  

  

  a 
  

  

  e 
  

  

  bD 
  

  

  i 
  

  

  s 
  

  

  

  W 
  

  

  fc 
  

  

  H 
  

  

  o 
  

  

  M 
  

  

  05 
  

  

  p 
  

  

  02 
  

  

  O 
  

  

  P 
  

  

  Fh 
  

  

  Ph 
  

  

  > 
  

  

  S 
  

  

  < 
  

  

  

  o 
  

  

  o 
  

  

  o 
  

  

  

  

  

  

  

  

  

  

  o 
  

  

  

  

  o 
  

  

  o 
  

  

  

  

  o 
  

  

  o 
  

  

  o 
  

  

  January 
  

  

  15.8 
  

  

  18.6 
  

  

  18.3 
  

  

  10.7 
  

  

  17.4 
  

  

  19.0 
  

  

  18.7 
  

  

  10.3 
  

  

  17.9 
  

  

  14.7 
  

  

  22.5 
  

  

  16.4 
  

  

  21.4 
  

  

  16.8 
  

  

  17.03 
  

  

  February 
  

  

  17.2 
  

  

  19.0 
  

  

  18.2 
  

  

  16.3 
  

  

  16.9 
  

  

  19.2 
  

  

  16.0 
  

  

  4.2 
  

  

  5.9 
  

  

  7.6 
  

  

  8.5 
  

  

  21.9 
  

  

  5.3 
  

  

  21.6 
  

  

  14.13 
  

  

  March 
  

  

  24.0 
  

  

  7.9 
  

  

  14.9 
  

  

  14.4 
  

  

  17.7 
  

  

  20.7 
  

  

  12 
  5 
  

  

  7.9 
  

  

  10.8 
  

  

  8.4 
  

  

  18.0 
  

  

  27.9 
  

  

  8.5 
  

  

  21.4 
  

  

  15.36 
  

  

  April 
  

  

  May 
  

  

  7.1 
  

  

  4.7 
  

  

  6.3 
  

  

  6.8 
  

  

  6.5 
  

  

  4.9 
  

  

  7.6 
  

  

  7.9 
  

  

  5.5 
  

  

  6.3 
  

  

  4.4 
  

  

  12.4 
  

  

  3.3 
  

  

  7.2 
  

  

  6.49 
  

  

  8.2 
  

  

  8.7 
  

  

  7.9 
  

  

  7.6 
  

  

  5.7 
  

  

  7.1 
  

  

  4.3 
  

  

  3.3 
  

  

  7.4 
  

  

  8.6 
  

  

  6.8 
  

  

  8.9 
  

  

  4.0 
  

  

  6.1 
  

  

  6.76 
  

  

  June 
  

  

  6.0 
  

  

  4.5 
  

  

  .4.6 
  

  

  2.5 
  

  

  5.3 
  

  

  5.1 
  

  

  5.5 
  

  

  3.7 
  

  

  *18 
  

  

  4.6 
  

  

  1.8 
  

  

  8.0 
  

  

  5.8 
  

  

  2.4 
  

  

  5.56 
  

  

  or 
  

  

  4.58 
  

  

  July 
  

  

  3.2 
  

  

  5.3 
  

  

  6.4 
  

  

  5.6 
  

  

  4.2 
  

  

  8.7 
  

  

  5.3 
  

  

  4.9 
  

  

  7.8 
  

  

  8.3 
  

  

  5.3 
  

  

  5.0 
  

  

  3.9 
  

  

  1.0 
  

  

  5.00 
  

  

  August 
  

  

  4.0 
  

  

  4.7 
  

  

  5.9 
  

  

  7.1 
  

  

  5.2 
  

  

  3.9 
  

  

  8.2 
  

  

  3.4 
  

  

  5.4 
  

  

  4.0 
  

  

  0.2 
  

  

  2.7 
  

  

  6.7 
  

  

  1.8 
  

  

  4.51 
  

  

  September 
  

  

  9.2 
  

  

  7.9 
  

  

  6.6 
  

  

  G.C 
  

  

  5.7 
  

  

  9.8 
  

  

  2.3 
  

  

  1.8 
  

  

  1.8 
  

  

  2.7 
  

  

  4.8 
  

  

  9.4 
  

  

  5.7 
  

  

  6.8 
  

  

  5.79 
  

  

  ■October 
  

  

  6.8 
  

  

  10.2 
  

  

  3.3 
  

  

  5. 
  5 
  

  

  5.9 
  

  

  8.1 
  

  

  3.4 
  

  

  4.9 
  

  

  6.9 
  

  

  7.7 
  

  

  9.5 
  

  

  6.8 
  

  

  5.8 
  

  

  2.0 
  

  

  6.20 
  

  

  November 
  

  

  8.3 
  

  

  10.6 
  

  

  5.5 
  

  

  7.9 
  

  

  4.9 
  

  

  4.4 
  

  

  6.8 
  

  

  8.1 
  

  

  11.9 
  

  

  8.1 
  

  

  15.7 
  

  

  10.3 
  

  

  12.0 
  

  

  10.3 
  

  

  8.91 
  

  

  December 
  

  

  28.2 
  

  

  13.3 
  

  

  22.0 
  

  

  20.0 
  

  

  25.8 
  

  

  25. 
  5 
  

  

  20.9 
  

  

  6.8 
  

  

  10.0 
  

  

  10.6 
  

  

  15.9 
  

  

  33.7 
  

  

  8.2 
  

  

  22.3 
  

  

  18.80 
  

  

  Tear 
  

  

  3.4 
  

  

  6.7 
  

  

  5.3 
  

  

  8.2 
  

  

  7.1 
  

  

  fi.2 
  

  

  3.0 
  

  

  0.7 
  

  

  3.6 
  

  

  2.0 
  

  

  1.1 
  

  

  

  3.7 
  

  

  4.8 
  

  

  4.21 
  

  

  * 
  This 
  large 
  variation 
  indicates 
  an 
  evident 
  error 
  iu 
  the 
  mean 
  of 
  this 
  month 
  for 
  1872. 
  Omitting 
  1872, 
  

   the 
  extreme 
  variation 
  is 
  4.3. 
  

  

  