There are 2 titles associated with this firm.

@book{ wphp_18938
  author={Opie,Amelia},
  year={1807},
  title={Simple tales: by Mrs. Opie. In two volumes.},
  publisher={John March \& },
  address={Georgetown},    }
@book{ wphp_19101
  author={Porter,Jane},
  year={1810},
  title={The Scottish chiefs, a romance. : Five volumes in two. By Miss Jane Porter, author of Thaddeus of Warsaw, and Remarks on Sidney's aphorisms. (From the London edition of 1810.)},
  publisher={David Longworth \& },
  address={New York},    }