1817.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



105 



" The arches which rjecnrate some portion of this aqueduct are not only 

 well proportioned, but receive further einbeMishraent frorn a regular ord.-r of 

 Corinthian coluruns: where the passage is preserved through the line, the 

 elevation is increased by an additional height. The section at the side shows 

 the channel for the streiira, which flowed in the attic, built above the order, 

 covered in by a vault carefully worked and well tied togeiln-r : here every 

 precaution seems to have been taken to guard against leakage, which, if it 

 ever happened, would be immediately discovered, by the pouring out of the 

 water at the defective place ; and along the whole line of aqueduct, mate- 

 rials were deposited, that there might be no delay m the work ; there would 

 be also less to perform than to take up a whole length of mains laid under 

 a solid and hard pavement, rendered impassable during the progress. Such 

 an inconvenience in crowded streets, the Romans wisely avoided, and con- 

 tinued to prefer the system of raised aqueducts to those buried in vaults 

 under ground." 



AQnA VIRGINE. 



Th« engravings of this viaduct, and also of tlie Gate of Augustus, 

 at Fano, show a combination of the Trabeate and Arcuate architec- 

 ture, so much adopted by the Romans; although it is highly ornate, 

 tlie combination of the two do not appear to form one construction:— 

 the Trabeate looks like an accessory to the Arcuate, and put up after 

 the latter had been erected. This barbarism of attaching idle, un- 

 meaning columns and entablatures to useful, effective arches, is com- 

 pared by Hope, in his Architectural Essay, to the barbarous treatment 

 of his subjects by the tyrant Mezentius, who tied living men to dead 

 corpses. Many a modern architect would do well to think over this 

 comparison. 



Drainage was also well understood bv the Romans, as may be shown 

 by the great drainage of the Pontine Marshes, 26 miles in lenglh, and 

 the Cloaca Maxima, a sewer U feet in width and 32 feet hicrh for the 

 drainage of the Imperial (Jity. The drainage of the lak?s Albano 

 and Fucino may vie with any of our modern works. 



We must, however, abruptly terminate our extracts from Rome, or 

 we shall trespass too far for the length of our review ; and proceed 

 at once to France. It is necessary, however, to make the preliminary 

 remark, that Holland and Germany are briefly dismissed in two pages, 

 without a single illustration: this conciseness is to be regretted as 

 those countries affbrd some noble examples of engineering; particu- 

 larly Holland, in its canals, sea walls, and works of drainage. 



Engineering in Fkance is very fuUv noticed, with ample illustra- 

 tions. Mr. Cresy has availed himself of the numerous treatises on 

 engineering which form so valuable a portion of French scientific 

 literature ;-he has given detailed accounts of all the principal ports 

 and harbours of France. The description of the celebrated break- 

 water at Cherbourgh, formed by truncated timber cones, 150 feet 

 diameter at bottom, 60 feet at top, and 70 feet high, is highly inte- 

 resting. The lighthouses and canals are next given, and are fallowed 

 by engravings ot numerous bridges erected in France, one of which 

 we have selected as a good specimen of French bridge-building:— 



"The Bridge of Sevres, over the Seine, on the road from Paris to Ver- 

 sallies, was designed by M. Becquey de Beaupre, and executed bv M Vieou- 

 reux; it was finished in 1820, and consists of nme principal semicircular 

 arches, 59 feet in span, and two lesser 16 feet 4 inches in span for the tow- 

 ing path The tnickness of the piers is 1 1 feet 5 inches ; the width of the 

 bridge 42 feet / mches. It occupies the situation of an old wooden bridge 

 and the axis is in the direction of the dome of the Invalides. The piers' 

 were founded by means of caissons. The arches were constructed on 

 trussed centres, which did not change their form during the placing of the 

 vouissoirs. o r & 



All the arches were keyed in July, 1815, except the erst on the right bank 

 where there still remained fourteen courses of voussoirs to place, when or- 



ders were given to break down the bridge, and the centre of this arch was 

 first set on fire, and the fourth blown up by two discharges, which caused 

 the rupture of some of the inner voussoirs of the arches, and it was after- 

 wards discovered that settlement bad taken place in the third, fourth, fifth 

 and sixth piers, the greatest of which was 2J inches. In 1818, the sixth 

 pier was loaded with 112 tons, without anv movement resulting; it was 

 thought fit, however, to discharge the weight bv means of arches in the 

 '""■*K. T^''<^/"»"^^t'7 Pilss were 3 feet 1 1 inches apart, and each carried a 

 weight of 52 tons ; the voidings, however, diminished this weight bv about 

 &4 tons. A general foundation was also constructerl bv throwing in'rubhle. 

 The settlements are attributed to th« efl-ect of the explosions; but they 

 would not perhaps, have taken place ba,i the piles been less loaded, or the 

 intervals between them been filled in with hydraulic masonry to a height of 

 b or 8 feet between the ground and the tops of the piles, instead of" with 

 masonry laid m common mortar, which does not harden under water 



In this beautiful example, the roadway is kept perfectly level throughout, 

 and the arches are all of the same span; this was rendered necessary, as 

 the banks on each side of the river were low, and it was not deemed advis- 

 able to raise the crown of the roadway, which might have been done on the 

 Pans side, but towards the town of Sevres it wuuld have been more difficult 

 to accomplish, as the houses on each side of the street, and the entrance to 

 the royal park, would have been equally inconvenienced. The piers all of 

 the same dimensions, are of great strength, their width being nearly equal 

 to a fifth of the span of the arch. 



The faces of the voussoirs, which are rusticated and rounded, increase in 

 depth towards the springing ; the effect is improved by this arrangement, 

 and we have an additional strength given where it is most required. For 

 the piers, abutments, and arch stones, the best stone which could be obtained 

 was made use of, and apparently the atmosphere has produced little change 

 upon It : as the stones laid in the quarry, so are they bedded, and their di.: 

 raensions and proportions are well defined for their respective situations. In 

 the spandrils and wing-walls, there does not appear to have been sufficient 

 attention paid to the backing, and inierior material is said to have beau 

 used. 



This bridge, which has a decidedly Roman character, of which fig. 1, 

 Plate Vlll., is a general view, is one of the best where semicircular arches 

 have been preferred to the elliptical; the same centre would serve for all the 

 arches, and there IS some economy in such an arrangement; hut the piers 

 occupy together upwards of 90 feet, while the breadth between the abut- 

 ments or water-way does not exceed 622 feet : by the adoption of a flatter 

 arch, fewer piers would have been required, and consequeotiv more water- 

 way would have been obtained: hut the whole is deservedly much admired 

 and Its design seems in harmony with the scenery around, and with the cha- 

 racter of the river : over a stream where the tide rose considerably, or the 

 navigation was more important, a holder design might have been intro- 

 duced. 



The elevation and section through the piers (figs. 2 and 3, Plate VIII ) 

 show Its solid construction, and the form also of its starlings : over the arch 

 are well contrived drains, which lead off the waters that fall upon the road- 

 way, an.i conduct them behind the spandrils into the stream below: the 

 blocking course, which forms the parapet, is supported upon a bold block 

 cornice; and the absence of all balustrade and rading greatly adds to the 

 effect of the structure. The roadway is paved thronghous, and at the sides 

 beyond the water-channel is a footway laid with a gentle inchnation." 



The works of the United States occupy a few pages, but no illus- 

 trations are given of the numerous engineering works with which 

 America abounds. 



Engineering in Great Britain next occupies a considerable 

 portion of the work, which we must pass over until next mouth, 

 giving now only the description of London Bridge, which we may 

 boast as being one of the finest specimens of bridge-bulldino- in the 

 world, and one of the noblest edifices of the City of LanJoo. ° 



"When the committee of the House of Commons had determined upon 

 the erection of a new bridge, Mr. George Rennie, at the desire of his father 

 the late Mr. Rennie, made the design as it is now executed ; and as the 

 country lost the services of Mr. Rennie by his death in 1821, the execiilion 

 of this important undertaking devolved upon his sons, and Mr. George Ren- 

 nie holding at that time a situation under the government, his brother, Sir 

 John, who was his junior, was named the acting engineer. Messrs. Jo'liffe 

 and Banks were the contractors, and the cost, including the approaches 

 amounted to £1,458,311 8s. lljd. The first pde for the cofl-erilam was 

 driven on the 15th of March, 1824, and the dam was finally closed on the 

 1st of April the following year, and after the water had been pu^nped out 29 

 feet below low-water mark, it was found remarkably tight. 



On the 2ah of April the workmen commenced their excavations in a stiff 

 blue clay, after which the sills and planking were laid read,- for the founda- 

 tions, which were commenced on the 15th of June: the first stone laid was 

 a piece of Aberdeen granite, 5 feet | of an inch long, 3 ft. 6^ in. broad, and 

 2 ft. 10 in. deep, cootaininc 50 ft. 7 in. cube, and weighing 4 tons. 



The cofferdam for the second pier was completed soon after, and pumped 

 out by the 24th of August ; in 1326 the foundalions on the Southwark side, 

 comprising the abutment and wing-walls, were carried up, and the second' 

 pier was commenced. 



The cofferdams of the first and second piers being no longer required, a 



15 



