l!\  sailinir  Direct  ions  orChart.     When  the  channel  has
k>Hg  ttretChai  Winding   between   shoaK  or  amoiiLf  M:mds.  the
sailini:  directions  or  chart  Drives  the  true  or   in.
and    bearings.      ^Suppose    they    ai.     i


PILOTING   OR  COASTING.  23

NE.,  till  a  certain  object  bears  N.  by  W.,  and  then  steer  E.
till  another  object  bears  SW.  lu  such  a  case  the  magnetic
course  and  bearing  are  given  to  rind  the  compass  course  and
bearing  of  the  object.  Look  in  the  3d  column  of  the  devia-
tion table  for  the  magnetic  course,  expressed  in  degrees  and
minutes.
If  it  be  not  one  of  the  courses  it  will  lie  between  two  of
them,  and  the  corresponding  compass  course  will  lie  between
two  courses  in  the  1st  column  and  may  be  found  by  estimat-
ing. To  find  the  compass  bearing  look  in  the  3d  column  for
the  magnetic  course;  opposite  to  it  in  the  2d  column  will  be
the  deviation  on  that  course.
Apply  this  deviation  to  the  magnetic  bearing  to  the  left  if
the  deviation  is  easterly  and  to  the  right  if  westerly.
EXAMPLE.
Suppose  the  chart  should  give  directions  to  steer  E.  till  a
certain  object  bore  N.  by  W.,  then  steer  SE.  till  another  object
bore  SSW.  magnetic.
In  column  3,  when  the  course  was  E. ,  the  deviation  was  be-
tween 6°  40'  E.  and  7°  30'  E.,  or  nearly  \  point  E.  Applying
this  to  the  left  of  the  first  course,  the  vessel  should  steer  E.  |  N.
by  the  compass  till  the  first  object  bore  by  compass  N.  by  W.
