﻿138 
  EEPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  North 
  Platte 
  are 
  on 
  the 
  same 
  parallel, 
  and 
  Mr. 
  Stolley's 
  locality 
  is 
  about 
  

   midway 
  between 
  them 
  in 
  the 
  same 
  valley 
  or 
  plain 
  we 
  may 
  take 
  the 
  mean 
  

   of 
  the 
  records 
  of 
  these 
  two 
  places, 
  which 
  differ 
  very 
  slightly, 
  as 
  repre- 
  

   senting 
  that 
  of 
  Hall 
  County. 
  

  

  In 
  this 
  case 
  the 
  eggs 
  were 
  deposited 
  August 
  13 
  and 
  14, 
  1876, 
  and 
  

   began 
  to 
  hatch 
  April 
  13 
  and 
  14, 
  1877. 
  

  

  The 
  number 
  of 
  days 
  during 
  which 
  the 
  maximum 
  temperature 
  was 
  50° 
  

   or 
  over, 
  and 
  also 
  the 
  number 
  of 
  days 
  during 
  which 
  it 
  was 
  60° 
  or 
  over,, 
  

   were 
  as 
  follows: 
  

  

  Months. 
  

  

  50° 
  

  

  60° 
  

  

  

  17 
  

   29 
  

   27 
  

   10 
  

   3 
  

   

   12 
  

   13 
  

   11 
  

  

  17 
  

  

  

  29 
  

  

  

  19 
  

  

  

  4 
  

  

  

  1 
  

  

  

  o 
  

  

  

  1 
  

  

  

  5 
  

  

  April 
  

  

  6 
  

  

  

  

  

  Total 
  

  

  122 
  

  

  81 
  

  

  

  

  In 
  order 
  to 
  ascertain 
  the 
  number 
  of 
  hours 
  they 
  were 
  exposed 
  to 
  these 
  

   degrees 
  of 
  heat, 
  respectively, 
  we 
  will 
  follow 
  Professor 
  Abbe's 
  estimate 
  

   as 
  nearly 
  as 
  possible, 
  keeping 
  in 
  mind 
  and 
  making 
  proper 
  allowance 
  for 
  

   the 
  difference 
  between 
  the 
  surface 
  temperature 
  and 
  that 
  at 
  which 
  the 
  

   eggs 
  are 
  placed. 
  We 
  obtain 
  the 
  total 
  number 
  of 
  hours 
  the 
  eggs 
  were 
  

   exposed 
  to 
  the 
  degree 
  of 
  heat 
  specified 
  by 
  multiplying 
  the 
  number 
  of 
  

   hours 
  during 
  a 
  day 
  in 
  which 
  the 
  maximum 
  was 
  at 
  or 
  above 
  the 
  given 
  

   degree 
  by 
  the 
  number 
  of 
  days 
  given 
  above 
  each 
  month. 
  

  

  Months. 
  

  

  O 
  u 
  

   C3 
  

  

  If* 
  

  

  Number 
  of 
  

   days 
  maxi- 
  

   mum 
  above 
  

   50°. 
  

  

  • 
  

  

  -2 
  8 
  . 
  

  

  pOcS 
  

  

  Number 
  of 
  

   days 
  maxi- 
  

   mum 
  above 
  

   60°. 
  

  

  Product 
  in 
  

   hours. 
  

  

  

  24 
  

  

  22 
  

  

  18 
  

  

  11 
  

  

  4 
  

  

  

  

  8 
  

  

  10 
  

  

  12 
  

  

  17 
  

   29 
  

   27 
  

   10 
  

   3 
  

   

   12 
  

   13 
  

   11 
  

  

  408 
  

   638 
  

   486 
  

   110 
  

  

  12 
  

   

  

  96 
  

   130 
  

   132 
  

  

  22 
  

   18 
  

   12 
  

   6 
  

   4 
  

   

   4 
  

   6 
  

   10 
  

  

  17 
  

   28 
  

   19 
  

  

  4 
  

   1 
  

   

   1 
  

   5 
  

   6 
  

  

  374 
  

  

  

  504 
  

  

  October 
  

  

  228 
  

  

  November 
  

  

  24 
  

  

  

  4 
  

  

  January 
  

  

  February 
  

  

  

   4 
  

  

  March 
  

  

  30 
  

   60 
  

  

  

  

  Total 
  

  

  

  122 
  

  

  2,012 
  

  

  

  81 
  

  

  1,228 
  

  

  

  

  

  

  From 
  this 
  we 
  see 
  that 
  if 
  50° 
  be 
  taken 
  as 
  the 
  minimum, 
  it 
  requires 
  

   2,012 
  hours, 
  1,228 
  of 
  which 
  must 
  be 
  above 
  60°, 
  to 
  hatch 
  the 
  eggs 
  in 
  the 
  

   latitude 
  of 
  Grand 
  Island, 
  Hall 
  County, 
  Nebraska 
  ; 
  or, 
  to 
  be 
  more 
  exact, 
  

   784 
  hours 
  between 
  50° 
  and 
  00°+ 
  988 
  hours 
  between 
  60° 
  and 
  75°+ 
  240 
  

   hours 
  above 
  75° 
  =2,012 
  hours. 
  

  

  Let 
  us 
  take 
  another 
  case 
  j 
  and 
  this 
  time 
  we 
  will 
  select 
  one 
  at 
  North 
  

   Platte, 
  Nebr., 
  one 
  of 
  the 
  points 
  selected 
  by 
  Professor 
  Abbe 
  in 
  illustrat- 
  

   ing 
  his 
  theory. 
  With 
  the 
  explanation 
  given 
  above, 
  the 
  following 
  table 
  

   will 
  be 
  understood. 
  Eggs 
  were 
  deposited 
  from 
  July 
  10 
  to 
  25, 
  in 
  187G, 
  

  

  