1842.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



419 



public, the communication between the to%vn of Kingston-upon-Tbames in 

 Surrey, and tlie hamlet of Hampton-wick in Middlcbcx, was carried on by 

 an old and incommodious wooden bridge, which was so dilapidated that any 

 attempt to put it into a substantial condition for the service of the public, 

 would have been equivalent to an entire rebuilding of the structure. 



The corporation of Kingston, therefore, resolved upon erecting a new 

 bridge, on a design by Mr. Lapidge, their architect, and in the year 1825 

 obtained an act of Parliament, granting them ihe powers necessary for that 

 purpose. 



The trustees appointed under the Act applied to the Exchequer Bill Loan 

 Commissioners for pecuniary assistance to the amount of £45,000. but the 

 application was not entertained until the working drawings, specification, 

 &c. had been submitted to their engiueer — the late Mr. Telford, when he 

 gave the following opinion : — " Having carefully inspected all the working 

 drawings, I consider it only justice to Mr. Lapidge to say, that they are very 

 complete and do credit to his judgment and assiduity; and as the blue clay 

 has been found quite across the bed of the river, I am of opinion that with 

 the precautions provided in the working drawings and specification, that the 

 work is very practicable, and if well executed will prove a substantial and 

 useful edifice." He also said. " 1 have gone through the detailed estimates, 

 and compared the same with the proposal accepted by the corporation, and 

 am satisfied that the works may be properly executed for the sum therein 

 mentioned, viz., Xi31,300 ;" and he stated " the amount of the general esti- 

 mate including the above sura — the expense of houses and ground — the 

 flood-arches and roads of approach, &c. to be £47,457." 



Upon receipt of this report, the Commissioners consented to make the re- 

 quired loan, but it being found that the Act limited the amount to be raised 

 to £40,000, alterations in the structure were suggested by Mr. Lapidge, 

 which received Mr. Telford's approval, and the works were commenced on 

 the reduced scale. 



The bridge is of Grecian architecture and consists of five elliptical arches ; 

 it is constructed chiefly of brick, with ashlar facing. The abutments are 

 terminated by towers, and the structure is surmounted by a cornice and 

 balustrade, with galleries projecting over the piers. The span of the centre 

 arch is 60 ft., with a versed sine of 19 ft.; the side arches are 56 ft. and 

 52 ft. span, and 18 ft. 3 in. and 16 ft. 6 in. rise, respectively. The highest 

 flood rises 6 ft. above the springing line, and the lowest summer level is 

 about the same distance below it. The foundations are all laid upon the 

 substratum of blue clay. The length of the bridge is 382 ft. to the ex- 

 tremes of the abutments, and the width between the balustrades is 25 ft. 

 The proportion of the piers to the span of the arches is about ^th. The 

 roadway is formed at an inclination of 1 in 40. 



The author then describes fully the constrution of the abutments, piers, 

 arches, and the superstructure. The work occupied about 2J years to the 

 completion, the first stone having been laid on the 7th of November, 1825, 

 and the bridge opened in form on the 17th of July, 1828. 



On the completion, Mr. Telford again made a report to the Exchequer 

 Bill Loan Commissioners in these terms : — " With Mr. Lapidge, I examined 

 the whole of the bridge and approaches, and taking it for granted that the 

 foundations of the piers and abutments, which are under water, and which I 

 had no opportunity of inspecting while in progress, are according to the 

 working drawings, all the other parts are found in a very perfect state, exe- 

 cuted in a workman-like manner." 



The bridge has in every respect answered the object for which it was in- 

 tended, and it has justified the good opinion Mi. Telford originally formed 

 of it. 



During the 14 years which have elapsed since its erection, it has required 

 none other than the most trifling repairs, and the expectations of the trus- 

 tees have been realized by the tolls having paid the allotted portion of the 

 principal, up to the present time, as well as the interest of the money bor- 

 rowed for its execution, and the cost of it did not exceed the amount of the 

 estimate. 



The communication was accompanied by seven remarkably well-executed 

 drawings, showing accurately all the details of the construction, and the 

 paper contained all the quantities of metals in the work, together with Mr. 

 Telford's reports upon it, with other documents of interest. 



" Description of Ihe Harbour of Port Talbot ( Glamor (jmishire)." By 

 Henry Robinson Palmer, V. P. Inst. 0. E. 



The harbour described in this communication is situated upon the outfall 

 of the river Avon, on the eastern shore of Swansea Bay. The adjacent 

 mountainous district terminates abruptly at about half a mile from the shore, 

 in a tract of marshy land, for the most part composed of sand, with de- 

 tached beds of clay and peat of various thickness, at about 10 ft. below the 

 surface. 



The river, which, at its issue from its rocky channel, had been diverted 

 from its course by accumulations of sand, nearly at right angles with its 

 point of discharge into the sea, would appear at some period to have bad a 

 direct channel thither. It has been the object of the author, by whom the 

 works were designed and executed, to restore this obvious course for tbe 

 land water, and by means of embankments, to convert into a dock that por- 

 tion of the old channel which extends through the marshes. A new channel 

 has also been formed from the outfall to a convenient part of the dock, with 

 a lock 48 ft. in width for the passage of vessels. 



As the works were undertaken by a few private individuals, every proper 

 economy was enjoined; and in order to diminish the expense of excavating 

 by manual labour, a channel of 100 ft. wide and a mile in length, Mr. John 

 Vigurs (whose extensive tin-plate and copper works are situated in the ad- 

 joining valley) proposed that the new channel should be formed by the force 

 of the land floods, which descend with great impetuosity. A trench of 20 ft. 

 wide by 10 ft. deep, was therefore cut in the line of the proposed channel ; 

 and a few days after it was finished, a heavy land flood descending from the 

 mountains rushed through it, carrying out to sea from the sides and bottom 

 of the trench an immense quantity of the soil. Every succeding flood in- 

 creased the size of the trench, and by judicious guidance of this natural ex- 

 cavator, the channel was formed of the requisite dimensions; and it is now 

 generally kept clear from accumulation by the land floods, but in dry seasons 

 by the sluices in the lock-gates. The bed of the channel is stated to form a 

 regular inclined plane of more than a mile in length, free from a shoal or any 

 other impediment. 



The confluence of the two channels has been rendered permanent, by a 

 pier of copper slag, with an active slope of 5 to 1. When finished, this pier 

 will extend full half a mile in length. 



The paper then describes generally the ordinary modes of constructiou 

 adopted in the works, and more particularly the lock, the cill of which is 

 23 ft. below the level of an ordinary spring tide : the coping is 2 ft. above 

 that level, and the gates are 23 ft. 6 in. high. 



The fabric of the lock is composed of hard silicious sandstone, cemented 

 with blue lias lime water. The ashlar work of the walls is 4 ft. in thick- 

 ness, witli counterforts, and the spaces between them are filled with rubble, 

 grouted with lime and sand. Tbe whole thickness of the walls may there- 

 fore be taken at 8 ft., excepting at their bases, where they are 10 ft. The 

 walls rest in part upon an inverted arch, 3 ft. in thickness, and tbe whole 

 mass, including the invert, rests upon a concrete of large and small rubble. 



The harbour is stated to be in immediate connexion with extensive copper 

 and tin-plate v;orks, and also with a great extent of coal-beds bordering the 

 valley of the Avon, and the trade is rapidly increasing, its position in the 

 Bristol Channel being highly favourable to a foreign trade. 



A plan of the harbour, with tbe streams and channels, and a transverse 

 section of the lock accompanied the paper. 



" Desei-ipticn of the Colder Viaduct, on the Wishaw and Coltness Railway, 

 with the Specijicafions, Estimates, and a series of E.xperiynents to ascertain 

 the Deflection of tiro of the Strutted Beams." By John Macneill, M. Inst 

 C. E. ■ 



When first the author v\as called upon to carry out the extension of the 

 Wishaw and Coltness Railway, he found that the funds for that purpose were 

 very limited, and that it was necessary to construct the works in the cheap- 

 est manner possible. To accomplish this it was necessary to design and lay 

 out a single line of railway, which would be sufficient to carry on the trade 

 by H. p., but if possible, and consistently with limited funds, to construct 

 the viaduct over the valley of tbe Calder (the principal work on the railway) 

 in such a manner as to be able to vviden it hereafter, and to make it suitable 

 for locomotive power, in tbe event of the trade being increased, or of the 

 railway forming a part of the great line of communication between England 

 and the West of Ssotland. Having these objects in view, and being so res- 

 tricted in funds, he was obliged to lay out the works in the first instance, 

 very ditferently from what he otherwise would have done, if there had been 

 ample funds. 



The valley of the Calder, which the railway had to cross, was nearly half 

 a mile in length, and tbe elevation of the line over the surface of the ground, 

 varied from 50 to 130 ft. The first intention was to construct a viaduct, 

 480 ft. in length, of stone arches, 60 ft. span and 12 ft. wide between the 

 parapets ; but as this mode of construction would have been the cause of 

 much expense, when it became necessary to widen the viaduct for a double 

 line of railway, and would also have involved an embankment of nearly 60 ft. 

 in height, composed of clay and marl, which was considered unsafe and likely 

 to slip, an effect which subsequent experience on other portions ot the line, 

 has since fully proved would have been the case ; it was determined to ex- 

 tend tbe viaduct to about 1200 ft. in length, and to construct it of timber 

 resting on stone piers, which allowed the means of widening and strength- 

 ening it hereafter, without stopping the trade or incurring more expense 

 than would have been necessary in tbe first instance, if built to the full di- 

 mensions. 



The piers and abutments are built hollow, of grey freestone from the ad- 

 joining quarry of Dalziel ; the trussed wooden beams rest in metal sockets, 

 and the springing plates are laid, for supporting the under arches of bent 

 timbers, which are now in progress of construction, to render the viaduct 

 capable of supporting safely the weight of locomotives and heavier trains 

 than now pass along it by h. p. The usual load for horses is 4 wagons, 

 each weighing 1} ton, and carrying 35 tons of coal ; there are frequently 3 

 of these trains in a single arch of the viaduct at tbe same time, and 30 

 loaded waggons weighing 120 tons exclusive of the engine and tender, have 

 frequently been taken over ; on one occasion a train consisting of 65 loaded 

 wagons of 4 tons each, making a gross load (including the engine and tender) 

 of 279 tons was taken over the viaduct, but the usual load is restricted to 

 30 tons, until the under arches are fixed. 



The details of tbe construction of the general work are then given, and 



