(former Guard House and Prison)
— 1816 —
Report from the Fort4 December 1815 · Captain Samuel Babcock, Engineer
I have the honor to enclose an estimate and plans of additions and repairs which I conceive necessary at Fort Mifflin. The Bombproofs which exist at present are in a state little fitted for the uses they were intended for, being very damp, dark, and approaching to decay. The one I have projected is intended to serve as a Guard House and Prison to be situated parallel to the revetment, one side facing the parade the other joining the rampart. The arch to be covered with earth, with small circular apertures grated instead of windows, which will furnish a supply of light and fresh air to make it dry and healthy.
By 1816 Babcock reported the building complete. For final construction a conventional frame gable roof with metal sheathing was substituted for a barrel vault covered with earth. The four-foot thick walls and iron grates, deeply set in the circular masonry openings, assured that no prisoner would escape. The chimneys in both the large and small rooms would have accommodated stoves for heating. Square insets in the brickwork over the circular windows on the north fa?ade appear to have been purely ornamental.
Documents from the 1835-1839 fort renovation identify the building as an Arsenal. Its role as Guard House was passed on to a new, smaller frame building between the main gate and the Quartermaster's Store. An Arsenal held all small arms - pistols, rifles, bayonets, and swords. In the 19th century they came from the main ordinance supply depots, the Schuylkill or Frankford Arsenals. During the Revolutionary War citizens worked for the Military Stores Department. A Voucher Book from 1780 in the National Archives identifies many people who were paid for their individual efforts. Foe example:
Patrick Fottrill received 190 pounds for cleaning and repairing 19 muskets
Mary Lorenz received 225 pounds for making 1800 flannel cartridges
Andrew Kuhn received 305 pounds 17 shillings and six pence for 29 days of work casting musket balls
Daniel Joy received 112 pounds 10 shillings for casting two iron 24 pound cannon, three 18 pounders and a wrought iron gun