﻿OF 
  TERRESTRIAL 
  MAGNETISM 
  AT 
  SEVERAL 
  PLACES, 
  ETC. 
  

  

  453 
  

  

  SECOND 
  SERIES. 
  

  

  The 
  observations 
  of 
  the 
  second 
  series 
  were 
  made 
  in 
  August 
  and 
  

   September 
  1835, 
  with 
  needles 
  A 
  and 
  C. 
  

   tains 
  the 
  results. 
  

  

  The 
  following 
  table 
  con- 
  

  

  TABLE 
  No. 
  XL 
  

  

  Observations 
  at 
  JVew 
  York. 
  — 
  Second 
  Series. 
  

  

  c 
  

  

  CD 
  

  

  B 
  

  

  w 
  

  

  Cm 
  

   O 
  

  

  6 
  

  

  v. 
  

   o 
  

  

  a 
  . 
  

  

  O 
  <u 
  

  

  a 
  ° 
  

  

  'w 
  ft 
  

   oi 
  

  

  Q 
  

  

  > 
  

  

  <D 
  

  

  to 
  

  

  og 
  

  

  «h 
  '43 
  

   O 
  

  

  (1) 
  

  

  "ed 
  

  

  Q 
  

  

  o 
  .« 
  

  

  <x> 
  fi 
  

   a 
  a 
  

  

  pq 
  

  

  ° 
  § 
  

  

  B 
  'S3 
  

  

  O 
  C3 
  

  

  '43 
  > 
  

   g 
  » 
  

  

  Qo 
  

  

  O 
  

  

  0) 
  

  

  o 
  

  

  W 
  

  

  R 
  

  

  .2 
  

  

  "cd 
  

   "o 
  

  

  Efl 
  

  

  o 
  

  

  o 
  

   d 
  

  

  

  Time 
  of 
  Ten 
  

   Vibrations 
  cor- 
  

   rected 
  for 
  Tem- 
  

   perature. 
  

  

  Weather, 
  

   &c. 
  

  

  Observer, 
  &c. 
  

  

  Hours. 
  

  

  Min. 
  

  

  Sec. 
  

  

  Fah.° 
  

  

  Sees. 
  

  

  Sees. 
  

  

  1 
  

  

  A 
  

  

  August 
  5 
  

  

  P. 
  M. 
  5.1 
  

  

  18 
  

  

  35.6 
  

  

  71.0 
  

  

  302 
  

  

  36.94 
  

  

  36.94 
  

  

  Cldy. 
  S.W.Bache. 
  Place 
  of 
  Observ. 
  

  

  2 
  

  

  a 
  

  

  <i 
  <i 
  

  

  " 
  5.6 
  

  

  19 
  

  

  12.8 
  

  

  71.0 
  

  

  310 
  

  

  36.95 
  

  

  36.95 
  

  

  Cumulus. 
  

  

  Yard 
  in 
  rear 
  of 
  dwell- 
  

  

  3 
  

  

  a 
  

  

  6 
  

  

  A.M. 
  10.8 
  

  

  20 
  

  

  19.0 
  

  

  68.9 
  

  

  330 
  

  

  36.94 
  

  

  36.94 
  

  

  Cloudy. 
  E. 
  

  

  ing 
  of 
  E. 
  Martin, 
  Esq. 
  

  

  4 
  

  

  a 
  

  

  tc 
  e< 
  

  

  " 
  11.3 
  

  

  17 
  

  

  07.0 
  

  

  69.7 
  

  

  278 
  

  

  36.94 
  

  

  36.94 
  

  

  Nimbus. 
  

  

  No. 
  31,5th 
  Street. 
  

  

  5 
  

  

  a 
  

  

  Sept. 
  10 
  

  

  P. 
  M. 
  5.1 
  

  

  17 
  

  

  33.0 
  

  

  762 
  

  

  284 
  

  

  37.07 
  

  

  37.04 
  

  

  Cldy. 
  S 
  W. 
  Bache. 
  

  

  6 
  

  

  tt 
  

  

  a 
  it 
  

  

  " 
  5.4 
  

  

  15 
  

  

  56.9 
  

  

  75.2 
  

  

  258 
  

  

  37.09 
  

  

  37.06 
  

  

  Cumulus. 
  1 
  

  

  7 
  

  

  a 
  

  

  ti 
  tt 
  

  

  " 
  5.7 
  

  

  18 
  

  

  39.2 
  

  

  73.5 
  

  

  202 
  

  

  37.06 
  

  

  37.04 
  

  

  tt 
  

  

  8 
  

  

  c 
  

  

  Sept. 
  10 
  

  

  P. 
  M. 
  7.5 
  

  

  16 
  

  

  19.4 
  

  

  73.5 
  

  

  296 
  

  

  33.08 
  

  

  33.08 
  

  

  Cldy. 
  S.W.'Bache. 
  

  

  9 
  

  

  " 
  

  

  a 
  a 
  

  

  " 
  7.8 
  

  

  16 
  

  

  32.2 
  

  

  71.0 
  

  

  300 
  

  

  33.07 
  

  

  33.07 
  

  

  Cumulus. 
  | 
  

  

  Mean! 
  

  

  'ime 
  of 
  Ten 
  Oscils. 
  at 
  70° 
  Fah. 
  

  

  in 
  Aug. 
  by 
  A, 
  36.941 
  in 
  Sen 
  

  

  d-arcs 
  of 
  4° 
  a 
  2°. 
  No. 
  of 
  Vibs. 
  1220. 
  

  

  " 
  

  

  it 
  it 
  

  

  Sept. 
  " 
  " 
  37.047 
  ' 
  

  

  it 
  a 
  it 
  744. 
  

  

  it 
  

  

  tt 
  it 
  

  

  " 
  " 
  C, 
  33.075 
  " 
  

  

  6° 
  a 
  2°. 
  " 
  596. 
  

  

  The 
  times 
  of 
  vibration 
  observed 
  in 
  the 
  beginning 
  of 
  the 
  month 
  of 
  

   August 
  are 
  all 
  less 
  than 
  those 
  observed 
  in 
  September, 
  probably 
  from 
  

   a 
  slight 
  change 
  in 
  the 
  magnetism 
  of 
  needle 
  A, 
  with 
  which 
  the 
  observa- 
  

   tions 
  were 
  made. 
  This 
  change, 
  however 
  small, 
  renders 
  it 
  expedient 
  

   to 
  compare 
  only 
  the 
  September 
  observations 
  with 
  those 
  at 
  Philadel- 
  

   phia. 
  From 
  the 
  mean 
  of 
  these, 
  we 
  have, 
  

  

  Relative 
  horizontal 
  intensity 
  at 
  New 
  York, 
  by 
  A, 
  0.94707, 
  

   " 
  " 
  " 
  " 
  C, 
  0.94697. 
  

  

  These 
  results 
  agree 
  very 
  well 
  together, 
  but 
  not 
  very 
  well 
  with 
  that 
  

   from 
  the 
  first 
  series, 
  Table 
  X. 
  As 
  from 
  the 
  comparisons 
  at 
  West 
  Point 
  

   and 
  Philadelphia, 
  there 
  does 
  not 
  appear 
  to 
  have 
  been 
  a 
  real 
  change 
  in 
  

   the 
  intensity 
  of 
  the 
  earth's 
  magnetism 
  between 
  the 
  times 
  at 
  which 
  the 
  

   two 
  series 
  of 
  observations 
  were 
  made, 
  it 
  will 
  probably 
  be 
  more 
  accu- 
  

   rate 
  to 
  take 
  the 
  mean 
  of 
  the 
  two 
  determinations. 
  Allowing 
  weight 
  

  

  