The Americana; a universal reference library, comprising the arts and sciences, literature, history, biography, geography, commerce, etc., of the world . Bec/ffocH Fig. 7. greater air pressure than that required to sus-tain a column of water of that hei,E;ht. Although the iron-lined timber caissons usedin the construction of the first East River orBrooklyn suspension bridge, measuring 102 feetby 168 feet eacli, with a working chamber gfeet 6 inches in depth, are among the largestever constructed, a clearer idea of the applica-tion of the pneumatic caisson method to worksof great magnitude may
The Americana; a universal reference library, comprising the arts and sciences, literature, history, biography, geography, commerce, etc., of the world . Bec/ffocH Fig. 7. greater air pressure than that required to sus-tain a column of water of that hei,E;ht. Although the iron-lined timber caissons usedin the construction of the first East River orBrooklyn suspension bridge, measuring 102 feetby 168 feet eacli, with a working chamber gfeet 6 inches in depth, are among the largestever constructed, a clearer idea of the applica-tion of the pneumatic caisson method to worksof great magnitude may be obtained from adescription of the caissons used in constructingthe foundations for the piers of the second EastRiver or Williamsburg suspension bridge, com-pleted in 1904. Tliis structure, although having a suspension. three. As determined by borings, the bed con-sisted principally of sand, and some clay andboulders. Below this, at a depth varying from45 to 75 feet below high water level, the forma-tion consisted of gneiss rock with a very irreg-ular surface. The caisson was sunk throughthe sand, clay and boulders until it rested onthe rock, which was then blasted away andstepped so as to make a fair bearing for theedge on all sides. The caisson measured 60feet by 76 feet on the sides, with a total depthof 19 feet, and a working chamber 7^ feet inheight. The walls were two feel nine inchesthick and were built of two courses of 12 by12-inch timbers, the outer course placed longi-tudinally and the inner vertically. Two layersof 3-inch planking were placed on the outside,and one layer on the inside. The bottom of
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectencyclo, bookyear1908
