﻿174 
  PEOCEEDINGS 
  OP 
  THE 
  CALIFORNIA 
  

  

  which 
  is 
  also 
  barometric, 
  and 
  which 
  is 
  3,917 
  feet, 
  and 
  we 
  have 
  14,898.5 
  ; 
  or 
  say 
  

   in 
  round 
  numbers, 
  14,900 
  feet 
  for 
  the 
  absolute 
  altitude 
  of 
  Mt. 
  Whitney 
  above 
  

   the 
  sea. 
  

  

  I 
  wish 
  to 
  correct 
  one 
  error 
  in 
  my 
  article 
  of 
  August 
  4th, 
  read 
  before 
  the 
  

   Academy. 
  

  

  The 
  magnetic 
  bearing 
  from 
  the 
  peak 
  which 
  Mr. 
  Belshaw 
  and 
  I 
  climbed 
  to 
  

   Mt. 
  Whitney, 
  is 
  there 
  given 
  as 
  N. 
  67° 
  W. 
  

  

  It 
  appears 
  from 
  subsequent 
  comparisons 
  with 
  the 
  maps, 
  and 
  with 
  other 
  obser- 
  

   vations, 
  that 
  that 
  bearing, 
  together 
  with 
  five 
  or 
  six 
  others 
  out 
  of 
  some 
  twenty 
  

   which 
  I 
  took 
  at 
  that 
  time, 
  was 
  affected 
  by 
  a 
  large 
  local 
  attraction 
  due 
  to 
  mag- 
  

   netic 
  iron, 
  distributed 
  with 
  great 
  irregularity 
  through 
  the 
  granite. 
  

  

  Not 
  being 
  able 
  to 
  see 
  from 
  any 
  one 
  point 
  on 
  that 
  peak 
  all 
  the 
  points 
  to 
  

   which 
  I 
  wished 
  to 
  take 
  bearings, 
  I 
  moved 
  the 
  compass 
  two 
  or 
  three 
  times 
  

   within 
  a 
  radius 
  of 
  25 
  or 
  30 
  feet. 
  But 
  the 
  compass 
  always 
  rested 
  on 
  the 
  rock. 
  

   The 
  result 
  happened 
  to 
  be 
  that 
  all 
  the 
  bearings 
  taken 
  from 
  one 
  of 
  the 
  points 
  

   (that 
  to 
  Mt. 
  Whitney 
  included), 
  were 
  affected 
  by 
  local 
  attraction, 
  while 
  the 
  rest 
  

   were 
  not. 
  The 
  real 
  magnetic 
  bearing 
  to 
  Mt. 
  Whitney 
  is 
  about 
  N. 
  ^3'^ 
  W. 
  

  

  This 
  error 
  afiects 
  also 
  the 
  triangulation 
  by 
  Mr. 
  Belshaw, 
  whose 
  results 
  are 
  

   given 
  in 
  the 
  note 
  to 
  that 
  article, 
  and 
  which 
  was 
  based 
  upon 
  the 
  bearing 
  of 
  

   N. 
  67° 
  W. 
  

  

  The 
  barometric 
  altitude 
  of 
  Mt. 
  Whitney, 
  as 
  given 
  above, 
  should 
  be 
  subject 
  to 
  

   slight 
  correction, 
  owing 
  to 
  the 
  fact 
  that 
  I 
  do 
  not 
  know 
  the 
  horory 
  curve 
  for 
  

   Lone 
  Pine, 
  and 
  that 
  nobody 
  knows 
  the 
  horory 
  curve 
  for 
  the 
  summit 
  of 
  the 
  peak 
  ; 
  

   but 
  any 
  correction 
  from 
  this 
  cause 
  would 
  be 
  small. 
  

  

  being 
  no 
  further 
  comparisons 
  witli 
  this 
  instrument, 
  which 
  is 
  a 
  short 
  one, 
  it 
  was 
  assumed 
  

   that 
  its 
  correction 
  remained 
  the 
  same 
  on 
  the 
  6th 
  of 
  September. 
  

  

  Next, 
  in 
  the 
  series 
  of 
  readings 
  at 
  Lone 
  Pine, 
  I 
  interpolated 
  other 
  readings, 
  both 
  of 
  the 
  bar- 
  

   ometer 
  at 
  32°, 
  and 
  of 
  the 
  detached 
  thermometer, 
  so 
  as 
  to 
  obtain 
  a 
  series 
  of 
  ten 
  readings 
  for 
  

   Lone 
  Pine 
  at 
  times 
  respectively 
  simultaneous 
  with 
  the 
  observations 
  on 
  the 
  peak. 
  The 
  remain- 
  

   ing 
  readings 
  at 
  Lone 
  Pine 
  were 
  rejected 
  in 
  the 
  computation. 
  The 
  series 
  of 
  ten 
  readings 
  for 
  

   Lone 
  Pine 
  so 
  obtained, 
  together 
  with 
  the 
  series 
  of 
  observations 
  on 
  the 
  peak, 
  were 
  then 
  cor- 
  

   rected 
  to 
  standard. 
  This 
  done, 
  the 
  mean 
  of 
  all 
  ten 
  readings 
  for 
  each 
  locality 
  was 
  taken, 
  both 
  

   of 
  the 
  barometer 
  and 
  the 
  detached 
  thermometer 
  ; 
  and 
  from 
  these 
  means, 
  the 
  altitude 
  In 
  

   queistion 
  was 
  computed. 
  These 
  means 
  were 
  as 
  follows 
  : 
  

  

  Barometer. 
  Detached 
  Thermometer. 
  

  

  At 
  Lone 
  Pine 
  2G.3(J2 
  89 
  2 
  

  

  On 
  Mt. 
  Whitney 
  17.835 
  '.'.'.'.'.'. 
  35.3 
  

  

  If, 
  instead 
  of 
  taking 
  the 
  mean 
  of 
  all 
  ten 
  observations, 
  the 
  successive 
  pairs 
  of 
  simultaneous 
  

   readings 
  be 
  taken 
  separately, 
  and 
  the 
  computation 
  made 
  for 
  each 
  pair 
  respectively, 
  there 
  will 
  

   be 
  found 
  to 
  be 
  at 
  different 
  hours 
  a 
  large 
  variation 
  in 
  the 
  " 
  temperature 
  term 
  " 
  of 
  the 
  formula, 
  

   and 
  the 
  results 
  so 
  obtained 
  will 
  range 
  through 
  something 
  like 
  a 
  himdred 
  feet 
  variation 
  of 
  

   altitude, 
  or 
  from 
  about 
  10,900 
  to 
  a 
  little 
  over 
  11,000 
  feet. 
  This 
  is 
  due 
  to 
  the 
  large 
  range 
  of 
  

   the 
  thermometer 
  in 
  the 
  valley, 
  which 
  was 
  far 
  greater 
  than 
  on 
  the 
  peak, 
  The 
  result 
  given 
  by 
  

   the 
  mean 
  is 
  much 
  nearer 
  the 
  highest 
  than 
  the 
  lowest 
  of 
  the 
  individual 
  results, 
  because 
  during 
  

   the 
  first 
  hovTr 
  of 
  observation 
  on 
  the 
  peak, 
  the 
  thermometer 
  in 
  the 
  valley 
  rose 
  rapidly, 
  while 
  

   after 
  10.30. 
  A. 
  M., 
  the 
  change 
  was 
  not 
  so 
  rapid. 
  

  

  The 
  altitude 
  of 
  Lone 
  Pine 
  itself— 
  8,917 
  feet— 
  was 
  obtained 
  from 
  Prof. 
  Whitney, 
  and 
  is 
  the 
  

   result 
  of 
  our 
  observations 
  there 
  for 
  a 
  week 
  or 
  so 
  in 
  1870. 
  The 
  altitude 
  of 
  the 
  peak 
  above 
  

   Lone 
  Pine, 
  obtained 
  in 
  the 
  manner 
  indicated 
  above— 
  10,981.5 
  feet— 
  is 
  probably 
  as 
  close 
  an 
  ap- 
  

   proximation 
  as 
  these 
  observations 
  give 
  the 
  means 
  of 
  making, 
  without 
  a 
  knowledge 
  of 
  the 
  

   horory 
  curves 
  or 
  monthly 
  variations 
  at 
  the 
  localities. 
  

  

  