OK, guys, the B&O car in question is a coal hopper.
B&O once had a big bunch of these 3-pot hoppers and yes, they date from the mid-19th century.
I believe there is at least one on display at the B&O Museum in Baltimore.
For those who might have my Carstens book on the Cumberland and Pennsylvania RR, see the photo on page 4,
showing several of the C&P's cars built from the same blueprints at the canal terminus in Cumberland.