﻿588 
  

  

  Effects 
  of 
  Iron 
  Masts 
  on 
  Compasses. 
  

  

  [June 
  17, 
  

  

  the 
  standard 
  compass, 
  and 
  oppose 
  the 
  downward 
  pull 
  of 
  the 
  ship's 
  

   vertical 
  force. 
  

  

  3. 
  That 
  the 
  quadrantal 
  deviation 
  is 
  slightly 
  increased, 
  and 
  the 
  mean 
  

   directive 
  force 
  remains 
  undisturbed. 
  

  

  4. 
  Lastly, 
  it 
  is 
  suggested 
  that, 
  as 
  the 
  magnetic 
  condition 
  of 
  a 
  mast 
  

   may 
  be 
  easily 
  ascertained 
  by 
  carrying 
  a 
  compass 
  round 
  it 
  at 
  stated 
  

   distances 
  and 
  parts, 
  the 
  mast 
  may 
  be 
  utilized 
  or 
  avoided 
  as 
  convenient. 
  

   A 
  similar 
  examination 
  of 
  the 
  mast 
  in 
  different 
  latitudes 
  would 
  enable 
  an 
  

   observer 
  to 
  eliminate 
  the 
  effects 
  of 
  transient 
  induced 
  magnetism 
  from 
  

   the 
  subpermanent. 
  The 
  amount 
  of 
  deviation 
  proceeding 
  from 
  these 
  causes 
  

   is 
  known 
  for 
  several 
  classes 
  of 
  ships 
  ; 
  but 
  what 
  part 
  iron 
  masts 
  supply 
  is 
  

   yet 
  a 
  subject 
  for 
  inquiry. 
  

  

  