said ferrous cylindrical wall having an outside surface, an inside surface, and a central axis, said {HEAD ~ outside surface} being {TAIL ~ a convex}, curved, outside cylindrical surface, said outside surface being contiguous said inside ends of said pole pieces, 
being
said ferrous cylindrical wall having an outside surface , an inside surface , and a central axis , said { HEAD ~ outside surface } being { TAIL ~ a convex } , curved , outside cylindrical surface , said outside surface being contiguous said inside ends of said pole pieces ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH