Steam Boat Corvette/Hyde & Clarke Agents. Blue 3-line handstamp on 1840 folded letter from "Little Rock, Ark" to New Orleans, blue "Steam" handstamp and manuscript "25" rate, endorsed manuscript "Corvette" at bottom left, Very Fine, a very rare packet marking, illustrated in Milgram, who notes that not only is this a very early marking but also the first to include the name of a steamboat agent. Milgram No. 295  Estimate $750 - 1,000. $0 (Image)