(Stamp Collars) Knowles Steam Pump Works, illustrated corner card and stamp collar on cover front bearing 1861, 3¢ rose, natural s.e. at right, tied by "Warren Mass. Feb 17" duplex (updated in manuscript to "18"); some flaws, Fine and very scarce and early stamp collar. Scott No. 65  Estimate $200 - 300. $0 (Image)