Conversely,  a  single  force,  acting  in  the  direc-
tion of  D  B,  Fig.  165,  against  a  surface,  B  C,
may  be  regarded  as  the  resultant  of  the  two  sep-
arate forces,  D  E,  and  D  C,  one  parallel  to  C  ±J,
and  one  perpendicular  to  it.  D  E,  being  parallel
to  C  B,  produces  no  pressure,  and  the  absolute
effect  of  the  force  will,  therefore,  be  represented
by  CD.
This  separation  of  a  single  force  into  two  or
more  separate  forces  is  called  the  resolution  of
forces,  the  force,  D  B,  being  resolved  into  the
components,  D  E  and  D  C.
Component  Currents. — (See  Currents,
Component?)

Component,  Horizontal,  of  Earth's  Mag-
netism   That  portion  of  the  earth's

directive  force  which  acts  in  a  horizontal  di-
rection.
That  portion  of  the  earth's  magnetic  force
which  acts  to  produce  motion  in  a  com-
pass needle  free  to  move  in  a  horizontal  plane
only.
Let  A  B,  Fig.  166,  represent  the  direction  and
magnitude  of  the  earth's  magnetic  field  on  a  mag-
netic needle.     The  magnetic  force  will  lie  in  the
plane  of  the  magnetic   merid-
ian, which  will  be  assumed  to  _D  A
be  the  plane  of  the  paper  C  A
D.    The  earth's  field,  A  B,  can
be   resolved   into   two  compo-  j
nents,  AD,  the horizontat com-  j
ponent,  and  A  C,  the  vertical  j
component

In  the  case  of  a  magnetic  !
needle,  like  the  ordinary  com-  J
pass  needle,  which  is  free  to  |
move  in  a  horizontal  plane  only,
the  horizontal  component  alone

directs  the  needle.    A  weight.
,.  ,  patients  of  Earth,  t

is  applied  to  balance  the  vertical       Magnetism.
component.
