These  measures  are  constructed  as  follows :  The  upright  piece  is  six  feet
long,  and  2^x|  inches ;  this  is  laid  off  in  inches ;  attached  to  the  upright
is  a  movable  arm,  Z,  about  18  inches  in  length,  having  a  thumb-screw  for
fastening  it  at  any  point  on  the  upright;  this  arm  is  fastened  at  right
angles ;  a  plumb  is  attached  to  one  end  of  the  movable  arm.  The  nfbvable
arm  in  this  case  is  fastened  just  65  inches  from  the  bottom  of  the  upright ;
hence,  when  the  measure  is  placed  vertically  on  the  bottom,  if  the  grade
line  has  been  reached,  the  arm  ought  to  touch  the  wire.  In  this  way  the
bottom  on  which  the  tile  rests  may  be  made  a  perfect  grade  and  parallel
with  the  wire.
It  is  important  that  the  tile  be  placed  in  soil  which  has  not  been  dis-
turbed, that  the  alignment  may  not  be  affected  by  the  tile  settling.  The
tile  should  be  laid  so  that  the  ends  are  brought  as, close  together  as  possible,
and  so  that  the  tube  will  be  continuous.
By  the  method  above  indicated  short  lines  of  tile  may  be  laid  on  a  per-
fect grade  without  any  survey  being  made,  by  first  determining  the  depth
of  the  ditch  at  each  end,  and  then  adjusting  the  wire  an  equal  distance
above  each  and  in  a  straight  line  between  these  points.  The  height  of  the
wire  above  the  surface  of  the  soil  is  immaterial;  but  it  must  be  placed
parallel  with  the  grade  on  which  the  tile  is  to  rest.
Those  who  are  interested  in  the  subject  of  drainage  will  find  much  of
interest  in  works  devoted  to  that  subject  by  such  authors  as  French,  Manly,
Miles,  Kilpart  and  Warring.
