Fig.  8. — Plan  of  Plough. 
608 
Report  on  Implements  at  York. 
so  that  when  one  shaft  is  turned  so  as  to  raise  its  ploughs,  the 
other  shaft  will  be  turned  so  as  to  lower  the  other  set.  On  the 
other  end  of  each  shaft  is  a disc,  having  a notch  at  one  end  of  its 
