There are ventilating flues and ejecting ventilators constructed in all parts of the centre building, and all of the windows and other openings throughout, are made secure by wrought iron gratings. All the floors are on iron beams and brick arches. The building is thoroughly fire proof in all parts except the chapel and roof framing, and is warmed by steam from two large boilers located in the boiler house on the east side of the jail, and lighted at night by gas. There is a thorough system of drainage from all of the waste pipes, soil pipes, and rain water pipes, through brick drains and sewers to Jones’ Falls, a stream running within about 200 feet of the jail. The entrance gateway and lodge, the clerk’s office and the residence for the warden, are on the south side of the jail lot, fronting on Madison street. There are two chambers over the lodge and office on the east side of the gateway. In the Warden’s residence, on the west side of the gateway, there is a kitchen, dining room, parlor, five chambers, and bath room, with hall passages, pantry, store rooms and closets, and all other requisite appurtenances and conveniences for the comfortable accommodation of a family. The yard for the warden’s residence is separated from the jail yard by a stone wall and iron gate. The prisoners are received and discharged through the gates on Madison street. The exterior walls of the jail and other buildings are all of stone, together with all the corbels, copings, quoins, chimney tops, &c. The base, up to the second range of window sills, is of granite, cut and set in large blocks. The walls above the base are of light blue stone, laid in rubbled masonry, with splayed jambs and arches. The window sills above the basement, and the quoins, corbels, copings and other dressings are of marble. The roofs are of slate. The interior walls, arches, &c., are all of brick. The site is a good one, being easy of access from all parts of the city, and convenient to the court house and penitentiary. There is ample space on all sides for a free circulation of air. The lot has a gentle ascent to the north and east, and a dry self-draining gravel sub-soil. Its proximity to Jones’ Falls, and its elevation above the water level, affords the best means of drainage. In designing this prison and working out the various details of the plan, we endeavored to carry out the following general principles, viz: 1. Confinement of prisoners in separate cells, so far as deemed desirable. 2. Separation into classes. 3. The cells so arranged that their doors and windows may have open gratings, and yet so as that a prisoner cannot from his cell see into any other cells or into any other part of the building except the corridor opposite his own cell. 4. The corridors so arranged and located that prisoners can, with convenience and safety, be allowed privileges in them.