Delafield, R. (1837). Letter of Capt. Richard Delafield, of the U.S. Engineer corps, to Matthew Newkirk, esq., president of the Philadelphia, Wilmington and Baltimore Rail Road Company, relative to a rail road bridge to be constructed over the Schuylkill at Gray's Ferry. Philadelphia: Printed by S.C. Atkinson.

Delafield, Richard. Letter of Capt. Richard Delafield, of the U.S. Engineer Corps, to Matthew Newkirk, Esq., President of the Philadelphia, Wilmington and Baltimore Rail Road Company, Relative to a Rail Road Bridge to Be Constructed Over the Schuylkill At Gray's Ferry. Philadelphia: Printed by S.C. Atkinson, 1837.

Delafield, Richard. Letter of Capt. Richard Delafield, of the U.S. Engineer Corps, to Matthew Newkirk, Esq., President of the Philadelphia, Wilmington and Baltimore Rail Road Company, Relative to a Rail Road Bridge to Be Constructed Over the Schuylkill At Gray's Ferry. Philadelphia: Printed by S.C. Atkinson, 1837.