Wells Fargo & Co., Sac. City, Mar 4. Double oval date stamp (Leutzinger type 11-5) on 1853 3¢ Nesbitt entire to San Francisco, with blue company printed frank at top, Very Fine and choice. Scott No. U10  Estimate $400 - 600. Controversy still exists over the significance of the "Blue Franks". Many believe that it was a steamship frank, as they came into existence when the steamship cancels disappeared in 1854, while others have conjectured that they may have denoted a special service. $0 (Image)