Annual report of the Boston Transit Commission, for the year ending .. . wWo o WOCO HO z § OO s*. Second Annual Eeport. 43 are mixed, combined with the requisite amount of water, anddischartred into iron buckets. The third maciiine, similar to the first, is Used to put theconcrete into place and to set footing-stones and steel-work. The upper 4 feet of excavation consists of surfacing andloam. Below this is found gravel and sand of variousdegrees of fineness to grade. The excavation of the sub-subway at Boylston street wasabout 40 feet deep, and extended 4 feet below mean lowtide. Here conside
Annual report of the Boston Transit Commission, for the year ending .. . wWo o WOCO HO z § OO s*. Second Annual Eeport. 43 are mixed, combined with the requisite amount of water, anddischartred into iron buckets. The third maciiine, similar to the first, is Used to put theconcrete into place and to set footing-stones and steel-work. The upper 4 feet of excavation consists of surfacing andloam. Below this is found gravel and sand of variousdegrees of fineness to grade. The excavation of the sub-subway at Boylston street wasabout 40 feet deep, and extended 4 feet below mean lowtide. Here considerable water was encountered which wastaken care of by a pulsometer. The bottom consisted of finesand. In order to protect the masonry from water and con-duct the latter to the pump-well, a 6-inch underdrain waslaid. On this an extra foot of concrete was placed, whichwas covered with plaster and waterproofing, and above whichthe regular invert was built. The trench has been excavated about 2 feet 6 incheswider than the subway, except along the Tremont-street the excavation extends on
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Keywords: ., bookauthorbostonma, bookcentury1800, bookdecade1890, bookyear1895
