Chap. VIII.

BRITAIN.

449

the shoes. These piles are to be of clean beech, elm, or fir timber, not less than 6 inchesthick, except those for the piers, which are to be fir timber, not less than 12 inches square,the whole to be well straightened, planed, ploughed, and tongued on the edges, and drivenperfectly close, and to be connected together with half timber fir waleings, well bolted andsecured to the piles. These piles are to be hooped and shod with wrought-iron hoops andshoes, averaging 26 pounds weight each for the small and 36 pounds weight each for thelarge piles. The above sheet piling to be pitched not less than 18 feet long each pile, andto be commenced previous to the main foundation, in order to facilitate getting down tothe required depth for the foundation.

“ Stairs -The foundations for the stair walls in front are to be excavated to such a depth

that the upper side or top of the platform may not be less than 34 feet 6 inches below thesaid Trinity House standard high water mark, decreasing backwards in depth accordingto the inclination of the abutments, as shown in the drawings ; bearing piles of beech, elm,or fir timber, not less than 12 inches diameter in the middle, are then to be driven not lessthan 12 feet below the under side of the platform of the foundation, that is, the square partsof the piles are to be of this depth, besides the shoes, and 4 feet from centre to centre; theheads of these piles are then to be cut off and levelled, and the earth from between is to beexcavated to the depth of 9 inches below, and the spaces are to be filled with Kentish rag-stone as before described, well beat down, and racked in with sharp gravel One tier ofsills not less than 12 inches square is then to be laid and solidly fitted on them, and wellspiked down to the piles with 18-inch best wrought-iron jagged spikes, not less thanl£ inches square; between the sills there is to be brickwork well bedded in mortar com-posed of three parts of clean sharp river sand to one part of the best lime, and the whole isto be well grouted and made solid to the level of the top of the sills. The whole area ofthe foundations is then to be covered with a flooring of 6-inch beech, elm, or fir plank,well bedded in mortar as before described, properly jointed, and firmly spiked down to thesills with the best wrought-iron jagged spikes 12 inches long, and ^ of an inch square;the whole of the sills and planking are to be laid so that they may break joint not less than4 feet beyond each other.

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SECTION THROUGH STAIRS OP LONDON BRIDGE .

“ All piles that break or split in driving, or that are wrong placed, or that do notgo in their proper direction, are to be taken out and replaced at the expense of the con-tractor.

“ 'Hie masonry of the abutments up to the springing of the arches is to be built or com-

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