I think the daughter of Thomas & Mary Birdsill, Mary, must have been married to a "Washington". I have a Helen Washington Smith married to John Dolman Spickett. I have her Father as Thomas Smith b. 4 Oct 1808, d. 1 Jan 1864 and her Mother as Mary Harriet Birdsill b. 26 Mar 1817 d. 16 Oct 1894. Married 25 Nov 1842. Only a guess with the Washington.