Chap. VIII.
BRITAIN.
315
The T head is supported upon cast-iron diagonal framing, 6 feet deep, on 18 columns,which are protected by transverse timbers, 13 inches square, bolted securely together.Under each of the columns are three cast-iron piles, 14 feet long and 15 inches in diameter ;these were driven into the bed of the river until their tops were 15 inches under water, atlow water ordinary spring tides.
On the heads of each of thepiles is an iron plate, uponwhich the column was placed.
The twenty-six columns ofcast-iron which support thewhole pier are each 18 feethigh and 33 inches in diameter.
The platform of the pier isenclosed by an open parapet,and the ends of the T are formedinto pavilions, which affordshelter in inclement weather.
At the end of the pier is a cast-iron column 35 feet in height,including the base and lantern,which is lighted every eveningwith gas.
Particular attention was re-quired to have the heads of theiron piles, which were driveninto the chalky bed, perfectlylevel before the bases were puton, and this was effected bymeans of a wooden cylinder,
9 feet in diameter, and 9 feetin length, made of 3-inchdeal battens, firmly keyed andhooped together, the lower endbeing shaped like a sheet pile,and shod with iron. Thiscylinder was lowered over eachset of three piles, and loadedsufficiently to cause it to sinkthrough the soft mud of theshore, when it was driven intothe hard ground. The water wasthen pumped out, and the mudremoved low enough to enablethe workmen to reduce theheads of the piles to a uniform level by chipping, so that the bases of the columns werefitted down to the tops of the piles, metal and metal, and this operation was repeated asoften as was required. *
Upon the columns are placed cast-iron ribs, 40 feet in length; each arch is composed oftwo, secured together by 1^ inch screw bolts and nuts. The whole structure consists offour such arches, which are strutted by other castings, firmly screwed to them. Thevarious portions of the iron framing, for the support of the platform, were fitted togetherin a temporary manner on shore, previously to their being applied to the columns, whichprevented any cutting or chipping away of the iron work already placed.
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Fig. 318.
Fig.319.
At the Terrace Gardens , lower down the river, another cast-iron pier has just been com-pleted, under the direction of Mr. J. B. Redman, which projects into the river 200 feet at