have  them  of  steel  wire  rope,  as  this  does  not  stretch  so  much
under  a  stress  as  cordage  of  the  same  strength.  Every  running
guy,  in  all  but  the  very  lightest  lifts,  should  be  composed  of  a
tackle,  the  arrangement  depending  on  the  weight  to  be  dealt  with.
This  should  be  the  case,  even  when  the  weight  has  only  to  be
lowered  by  the  guy  and  not  lifted.  If  the  hook  of  the  block
of  the  tackle  is  placed  in  a  bight  of  another  part  of  the  guy,
this  bight  should  be  protected  by  a  thimble.
Protection  of  this  nature  should  always  be  given  to  a  rope
which  would  otherwise  make  a  sharp  bend,  if  not,  the  rope  loses
one-quarter  to  one-third  of  its  strength.  The  guys  should  be
secured  to  the  head  of  the  spars  as  nearly  opposite  one  another
as  possible,  and  as  near  to  the  position  of  the  sling  or  lashing  of
the  lifting  tackle  as  can  be  managed,  to  avoid  transverse  stress
in  the  spar.  For  the  same  reason  the  leading  block  of  the  tackle
should  be  as  near  the  foot  of  the  spar  as  possible.
Foot-ropes  will  generally  be  required  as  a  precaution  in  raising
these  machines,  and,  if  a  sound  footing  cannot  be  obtained  in
the  ground,  they  will  also  be  required  while  the  machines  are  in
use,  especially  when  they  are  heleed  over.  For  heavy  spars  it
is  better  to  use  tackles  for  these  foot-ropes.  In  all  cases  where
foot-ropes  are  employed,  they  should  be  attached  as  near  the
point  of  rotation  as  possible,  so  that  the  alteration  in  their  length
that  has  to  take  place  during  the  operation  of  raising  may  be
reduced  to  the  minimum.
