San Francisco, Cal., Aug 9 (San Francisco). Clear cds (William SAF-280) and matching "Ship 6" clamshell handstamp on 1851 incoming cover with manuscript "Str Constitution" & "Per Mail Steamer" endorsements, same day docketing at left, Very Fine, reported to be the only known steamer endorsement from the non-contract steamer Constitution. Estimate  $400 - 600. Steamship Constitution was an independent steamer, making only 2 trips to Panama for J. Howard & Sons Empire Line and one for the Pacific Mail Steamship Co. in 1853. $0 (Image)