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