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394 The pier is divided into seven sec- tions by a longitudinal fire wall between the two tracks and three transverse fire walls, The northerly half of the structure has two stories, the second story being for passenger accommodation. The Substructure. Concerning the substructure of the building: There is a central core over a portion of the land end, which is of solid earth, this being taken advantage of to obtain. permanent foundations for certain of the steel columns and for the support of tracks through that por- tion .of the house. ~The. greater por- tion of the pier, however, is over water. Much difficulty was encountered over a portion of the work, due to the sunken debris resulting, in part, from the re- cent fire and, in part, from a disas- trous fire which occurred in this same place in 1895, where a pier substantial- ly the same width as the one now under construction and 300 ft. long., was en- tirely destroyed. The foundation is practically all sup- ported by:piles, those on the land por- tion, where permanent masonry' piers are used, being to some extent spruce, as they are entirely covered with earth. A large proportion of the shorter piles used throughout the structure were old piles recovered from the site of the new pier, or the best of the piles from the site of the other piers burned at the same time. All piles for the permanent support of the building at the steel col- umns are oak and, on account of the diffi- culty of getting long oak piles, a great number of them were spliced and lagged to get greater length and frictional re- sistance, the entire site being what is known as "friction ground', there being no hard bottom within a reasonable dis- tance. of the surface that could be reached by piles of any ordinary length. Where longer piles were needed than it was possible to obtain in oak, and where it will be possible, in the future, to make renewals, Southern yellow pine piles were used. whe fotal number of piles used throughout the pier structure was about 6,000. The lumber for capping of piles, and framing of the substructure throughout, where strength and resistance to décay is required, is long leaf southern yellow pine. Wood preservatives were freely used on the outer portion of the struc- ture, where it is subject to moisture other than the sea-water and, for the wave-stop which surrounded the land core to prevent the waves acting upon the earth, the timber was covered with three coats of teredo proof paint to tetard the action of sea worms which ~ THE Marine REVIEW are becoming active in our harbor, but which, however, do not seriously affect oak and some other timber, especially if the bark is on. . Concrete Apron on the Pier. On the outer edge of the pier frum a distance of 2 ft. below mean low water to mean high water, about 12% ft., there is a tight wall of 6-in. thick timber, and from the top of this to the level of the platform of the pier, there are concrete slabs, openings only being left in the slabs sufficient for ventilation. All tim- ber in the immediate vicinity of the ventilation openings is protected with fire resisting material. The object of the continuous curtain of timber and con- crete is to prevent floating, burning de- bris, or burning oil, from reaching the interior of the structure. The platform, 10 ft. wide, outside of the pier building, which is subject to fire exposure, is made of a solid rein- forced concrete slab 8 in. thick. The floor of the pier inside of the walls of the building is of heavy timbers sup- porting 3-in. planking. On the plank- ing, to prevent the passage of fire, is laid two layers of 4-ply plaster board and, on the plaster board, to protect it from in- jury in case of renewal of the wearing - surface of the floor, is matched board- ing 7 Of an inch in thickness... The wearing surface which is subject to re- newal is of 2-in. hard pine plank. The plaster board referred to is a material which has been tested repeatedly by the Factory Mutual Insurance labora- tories and shown to be one of the best fire resisting materials known. The tracks in the center of the build- ing previously referred to are depressed below the general floor level, so that the floor of cars is approximately on the level of the main floor of the building. AS a fire, stop at. this place-.a° curtain wall of cinder concrete is used. It is, therefore, seen that, with the exception of protected ventilating openings, the substructure of the pier is enclosed by practically continuous non-inflammable material. Similar construction to that of the outside curtain wall is used throughout, under both the longitudinal and trans- verse fire walls; that is, from below low water to a point at a height where tim- ber is always wet, there is a continuous 6-in. sheathing and, above this point, a solid concrete wall up the level of the finished floor, from which level the fire walls of the superstructure begin. The arrangement of the number of rooms above referred to was decided upon to prevent the rapid spread of fire, and was the subject of much consideration on the part of the railroad company's en- gineers in consultation with the under- October, 1909 writers, chamber of commerce and the building commissioner of the city of Boston, as was also numerous other de- tails of construction relative to the fire resisting features of the building. In connection with the substructure, it is necessary to provide excessively heavy outer corners to receive the impact of the steamers as they are docking, es- pecially when there are adverse winds and tides. Belaying posts of reinforced concrete are provided at frequent in- tervals in the- outer platform, heavily braced and tied to the superstructure. Two-Story Suverstructure. The superstructure is practically of steel frame construction throughout, con- sisting of two main spans of about 73 ft., with a central pair of spans about 36 ft. each, the central support being be- tween tracks, thus leaving the main thoroughfare for heavy teaming and general business in the outer 73 ft. span which: will be free and clear of all posts or other obstructions. The fire walls are of steel frame throughout. The ou- ter walls, where not made up of doors or windows, are covered with corrugated reinforced asbestos siding, a material absolutely incombustible, an excellent non-conductor of heat and a most ex- cellent material for pier construction where the structure has to withstand the tremors due to the impact of vessels when docking. Immense Cargo Space. On the first floor, with the exception of small areas required for offices in the north end, the entire area is avail- able for cargo. Offices and other con- veniences necessary, both on the first floor and on the second floor, are made, so far as practicable, of incombustible material similar to that previously de- scribed. in other parts of the structure, except that in one or two rooms, where special precautions have been taken, walls and ceiling are entirely of brick or terra- cotta.and, where sanitary conditions are necessary, asphalt or similar material has. been used to admit of thorough cleaning. In addition to the offices on the ground floor, a room for perishable freight is provided so that it can be heated if desired, and there are proper conveni- ences for the stevedore's gear. There is also. a parcel room on the ground floor for the steamship company's pat- rons. Passenger Accommodations. There 'will be drop stages on each side of the pier, operated by special machi- nery, to adjust themselves to the re- ceipt of the gangways from both the st eral A ais et aL 8