which  diminish  in  size  from  right  to  left.  The  roughing  rolls
revolve  at  about  70  revolutions  per  minute,  and  the  finishing
rolls  at  about  90  revolutions  per  minute.  The  iron  is  first
passed  through  the  largest  groove,  and  so  on  to  the  smallest,
or  until  the  bar  is  of  the  desired  thickness.
