The walls are of red sand-struck brick, trimmed with brown sandstone and special dark brick. All brickwork was laid in 1 to 3 Portland cement mortar. Roofs are of green slate and copper. The framing is of steel columns, girders and roof trusses, with beams and rafters of southern pine. Floors are of three-inch spruce plank, with seveneighths inch maple top, except in basements and in the general laboratory, where concrete floors are used. Roof planking is of two-inch spruce. All timber and under sides of floor and roof planks are dressed and exposed in open framework. Minor partitions in the wings are of plaster on wood laths. Partitions about the instrument room and the workshop in the general laboratory are of sheathing. Interior brick walls are painted and exposed framing and plank ceilings are either stained or oiled. Doors and interior wood finish are of red oak, with dull rubbed finish. While in no sense fire-proof, the construction may be termed "slow burning," and the fire risk is somewhat reduced by the brick fire wall which separates the general laboratory from the corridors and the wings. All openings in this wall are provided with automatic fire doors. Fourteen lines of two-inch hose are placed in the building and have connection to the city high service system. The framing in the general laboratory gives a center bay 28 ft. wide extending the entire 200 ft. of length, and supports the track girders, upon which a ten-ton electric travelling crane is operated. The crane accommodates the entire center bay and can land loads on the second floor gallery, which extends entirely around the room. The side bays are 12 ft. in clear width, with the second floor galleries 14 ft. wide, because of two-foot cantilever projection into the center bay. On the third floor level, a gallery extends the full length of the building on the north side of the laboratory. The galleries are served by twoton trolley hoists, covering their entire length and in the first story connecting with the lecture room, so that apparatus from the laboratory may be easily placed upon the lecture platform. The concrete floor of the general laboratory, supported on the soil except over the storage room at the east end, where a reinforced concrete floor preserves the continuity of the surface, is provided with cast iron bolt sockets, spaced four feet on centers, to permit of fastenings for laboratory apparatus. The central portion is made ten inches thick to provide for heavy machines, and is underlaid with ducts and hand holes for wiring to the apparatus located in this section. The building is furnished with both live and exhaust steam, by pipes from the central station of the institute. Direct radiation is used for heating the large laboratory and is the principal source of heat for the entire building. For ventilation of offices, recitation, lecture and design rooms, air from a heating chamber, located under the front steps, is forced through tunnels and ducts to these rooms, while vent ducts exhaust through the roof of each wing. The Webster vacuum return system is used throughout. The lighting is accomplished mainly by 220-volt incandescent lamps, with holophane shades. How |