E B. O'Callaghan became keeper of historical manuscripts for the State of New York in 1848. In that role he completed the original translation of the Register of the Provincial Secretary, 1638-1642.

Prior to his appointment, O'Callaghan led an interesting life as a medical doctor and noteworthy political reformer. Born in Ireland ca. 1797, he immigrated to Lower Canada in 1823, joined the political reform movement of the Parti Patriote, and was subsequently elected to Lower Canada's legislative assembly. In 1837 during the Lower Canada Rebellion, O'Callaghan fled an order of arrest and crossed into the United States.

After his arrival in Albany, O'Callaghan contributed to The Northern Light, a journal "Devoted to free discussion, and to the diffusion of useful knowledge, miscellaneous literature, and general intelligence" that was sympathetic to the anti-rent agitation in the area. His interest in the topic compelled him to learn Dutch in order to understand the Patroon's land claims. His linguistic skills subsequently led to his employment with the State of New York, a position in which he compiled many volumes of colonial records and translated many of the Dutch-era documents.

He died in 1880 in New York City.