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chosen surveyor on the 27th of February, 1760. The 

 foundations of the piers were piled, to guard against a failure 

 like that which occurred in one of the arches of Westminster 

 bridge; but the caissons on which the piers are laid are 

 considerably distorted. The bridge was placed as near as 

 possible at right angles to the stream of ebb and flood. 



The bridge itself cost 152.840/. ; but before it was opened 

 a temporary way for passengers was carried across the 

 arches, by which 17572. was added. The total expense was 

 however so much increased by the embankments and ap- 

 proaches, that it was estimated in 1 76G at 232,1 851. 12s. tid., 

 and amounted in the end to nearly 300, OOOl. The shares 

 were about the same time bought up by government, and 

 the bridge made free to the public by the removal of the 

 toll which had been placed on it. 



The soft nature of Portland stone, of which the bridge is 

 built, and its unfitness for water-works, will satisfactorily 

 account for the decay of the piers and cutwaters, as well 

 as of many of the arch-stones. The attention of the city au- 

 thorities having been called to the dilapidated state of the 

 bridge, Messrs. Walker and Surges, engineers, were em- 

 ployed to survey it, and from their report, read at a common- 

 council held on the 25th of April, 1833, it appeared, that 

 the works above low water would cost 60.000/. repairing, 

 and 30,000^. would be required for piling, coffer-dams, and 

 securing the foundations. The foundations were examined 

 by means of Deane's patent helmet, and a full detail of the 

 state of the works is given in the report. 



An act of parliament was immediately applied for and 

 obtained, and the works of repair begun, under Messrs. 

 Walker and Burges's direction, early in the following sea- 

 son. In these the chief object has been to protect the 

 foundations from the effects of the increased depth and 

 scour of the river in consequence of the removal of old 

 London bridge, by a casing of piles round the piers, covered 

 with masonry ; and generally to restore the decayed parts 

 of the superstructure. The architectural character of the 

 bridge has not been materially interfered with, the only 

 alterations contemplated being that the cutwaters are to be 

 widened and made higher, and to be built of granite ; the 

 columns are to be shortened, which will improve them, as 

 they are now higher than the rules of architecture admit; 

 and the present balustrade removed, and a plain parapet 

 substituted. 



Great ingenuity has been displayed in the method of 

 restoring the defective arch-stones. The aperture to be 

 filled up being wider at the back part than the front, causes 

 difficulty in efficiently repairing arches so dilapidated ; for 

 although a few stones may be repaired in an indifferent 

 manner, and may not affect the stability of the structure, 

 yet, when a fourth of the whole soffit has to be replaced, as 

 has been done in the Surrey arch, it is of the greatest im- 



[Cut showing the plan of the cutwater restored. The doited line shows 

 ' ' the decay of the stone to that margin.] 



When it is necessary to replace a stone high up in the 

 arch (for instance, a part of the key-course), as the ping 

 which connects the two thicknesses lies horizontally and 

 cannot fall into its place, the workmen are obliged to bore a 

 small hole from the chamfer to the back, of the large hole in 

 the thickest stone, through which the'y pass another cord 

 which is fastened to the other end of the plug.t A small 

 groove is made in the beds of stone to protect the strin"- 

 while the wedge stone is driven home, which being done, 

 it is only necessary to loose one cord and pull the other, and 

 the plug is immediately brought into the hole in the other 

 stone. By this means the two stones are so connected that 

 it is impossible for one to come out without the other. The 

 annexed sections of the stones will make this more intel- 

 ligible. 



portance that each stone which is inserted should do the 

 duty of the one which was originally there. This object is 

 attained by the plan adopted. 



The broken or decayed parts of the arch-stones are gene- 

 rally cut out to the depth of fifteen inches. After the old 

 work has been properly prepared, the space is filled up with 

 two stones or thicknesses instead of one. The one first laid, 

 which we will call the lower stone, is thicker at the back 

 than at the front by rather more than the difference of the 

 heights of the front and back part of the whole course of 

 which it is a part. Suppose the course to be fitted in is 

 two feet five inches high in front, and two feet six inches 

 at the back, the lower stone is made one foot five inches 

 high on the face, and one foot six and a half inches at 

 the back. The other stone will then require to be thinner 

 behind than before, and in the case supposed will be twelve 

 inches in front and eleven and a half behind ; or, in other 

 words, it is a stone wedge fifteen inches deep, with a draught 

 of half an inch, which, when driven back, causes the two 

 thicknesses to take a bearing with the old work. 



In the centre of the bed of this upper stone a hole is 

 bored, into which, previous to its being driven, is put a cir- 

 cular stone plug, tapering from the middle towards each 

 end; to this plug a cord is attached, which passes through 

 a hole drilled from the chamfer outside to the upper part 

 of the large hole, where it is fastened to the top of the stone 

 plug. By this means the plug is kept steady during the 

 operation of driving. When the upper stone has been 

 driven into its place, the cord is loosened, and the plug falls 

 half its length into a hole, which has been made to receive 

 it, in the lower stone. > 



j 



is 



Figure A shows a stone just ready to be driven to its 

 place ; 1 is the wedge in which the plug a is kept steady 

 by a cord which comes through a hole to the chamfer, 

 and is made fast round a piece of wood at 2 ; 3 is the 

 other half already set, with its hole 4 to receive the plug 



when 1 is driven home ; 5 is a weight (most commonly a 

 mason's chisel) which keeps the cord tight that is attached 

 to the end of the plug marked a, by which it is drawn into 

 the hole 4. Figure B shows a stone finished, with the plug 

 drawn into the hole of the stone which was first set. Soft 

 mortar is then forced through the hole b so as to fill up the 

 whole of the space round about the plug, which being thus 

 imbedded, it is impossible for it to move. 



To ascertain if the plug is in its proper place, a piece of 

 iron with a joint is passed into the hole bored from the 

 upper chamfer, which, if it enter into the hole, proves that 

 the plug is in its proper place. If the plug cannot be got 

 in, which rarely happens, the upper piece of stone has to 

 be cut out again. 



In each of the piers there will be nearly 10,000 cubic 

 feet of granite. Four dams in all are to be formed. The 

 quantity of timber in that round the fifth pier is about 

 30,000 cubic feet, the sheet-piling consisting of half timbers. 

 The approaches to the bridge on both sides are intended 

 to be improved by being made less steep. The cornice 

 line, which is now very irregular, is to be altered so as 

 to be flatter than at present. It was proposed to widen the 

 bridge, but this project has been abandoned, from a wish to 

 preserve the columns, which, however beautiful they may 

 be in themselves, are not of that value which the proposed 

 alteration would have been to the public. (Narrative re- 

 ferred to in Ike Report of the Committee to the Common 

 Council, 14th May, 1784, 'MS. ; Report of Common Coun- 

 cil on Blachfriars Bridge Embankment and Surrey Roads, 

 1784, MS.; Pennant's London; Report to the Common 



