(Machinery) W. Hovey's Patent. Illustrated design on buff cover to Pennsylvania franked with 1851 3¢ brownish carmine (four margins to just shaving frameline at bottom left) tied by unusual ultramarine grid cancel with matching "Worcester, Ms." cds, cover lightly folded horizontally prior to use, Extremely Fine, a rare design. Scott No. 11  Estimate $250 - 350. $0 (Image)