23 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Jan, 



attention of engineers was now directed to the formation of a harbonr of 

 fg, which mist, in his opinion, be detached fron, the ^hore,,n order to 

 permit the free run of the shingle. Sueh a harbour, or even a good break- 

 ^vater, behind which steamers could take shelter, would be extremely .^eful 

 narticuUrly iu case of war, as from the proximity to the French coast, Dover 

 dd require special protection. There were several ''^^'-"""''"f. '"„'';, 

 course of his practice, Mr. Giles bad seen these views exemplied. I^ridport 

 harbour consi^sted of two small piers and open timber jetties, through whnA 

 tlie shingle was carried, and was deposited in the entrance When he was 

 cafled upon to devise methods of improvement, he directed the open jetties 

 to be fifed up with rubble work, and by establishing a system of scouring 

 by sluices, the accumulation was carried away, dhoreham harbour was much 

 iJ eTame state, and in spite of all that had been done it ^'.H remained a 

 bar harbour. The harbour of Sunderland was liable to he choked up with 

 Mnd and but for the scour of the river Wear, it could with .hthculty be kept 

 onen' It, however, was still a bar harbour, an<l neither in it, nor in any 

 o her of the ports that had been mentioned, could vessels be received at low 

 water ; in fact, onlv during the time the tide was up. It would aUays be 

 observed, that upon coasts which were subject to the shifting of shingle, 

 "or mud, any solid projection would inevitably cause ettects analogous 

 to tl ose which had been mentioned ; and to which might be added, the in- 

 "tances of the works of the harbourof Courtown, County Wexford, commenced 

 by Mr. Nimmo, and continued by Mr. Giles. 



Sir John Rennie, President, said, that the chief object he bad in view, 

 in bringing the historv of the ancient port of Ostia before the Institution 

 «as independently of the interest which attached to such extensive works, 

 which had failed so entirelv from natural causes, to direct the attention of 

 the members to the important question of the elTect of the action of tides, 

 and of rivers, in the formation of deltas, shoals, and bars, at the entrances 

 of harbours. Some instances had been given of a few of the English har- 

 bours but the opposite coasts of France and Holland exhibited, in a more 

 marked degree, the eHects of this action, not only in the bars^of the har- 

 bours but in the formation of banks parallel with the shore. The ports of 

 Dunkernue, Calais, Boulogne, and Havre, might be especially mentioned 

 In all of them, in spite of continued extension of the jetties, and constant 

 attention to the works, the accumulation of matter at the entrance extended 

 with the new works. Hav:e was, perhaps, the most extraordinary instance. 

 The current, at the entrance, was at times so strong, that a powerful steam 

 vessel, such as the " Phoenix," had found much difficulty in entering the 

 harbour. 



The formation of the Goodwin Sands was a subject of interesting obser- 

 vation There could not be anv doubt of these sands being formed by the 

 action of the eddies of the tide and the river Thames ; an attentive study of 

 the position, with respect to the headlands near, the currents of the river and 

 the tidal waters, hearing in mind the direction of the prevailing winds, en- 

 abled a reasonable solution of the problem to be arrived at. 



Dover harbour was a curious example of the effects of the motion of 

 shingle, which was produced from the debris of the fallen chalk cliff, the 

 flints of which formed the pebbles, and the chalk and earth composed the 

 silt In the time of Henrv VIII,, Dover bay was instanced as being very 

 fine and having verv deep water. The prevailing winds caused the shingle 

 and' silt to be carried to and fro freely along the shore. As soon as an ob- 

 struction was offered by piers, the shingle, having no longer a free and unre- 

 stricted course, accumulated across the ends of the piers, forming an em- 

 bankment enclosing one side of the lake, which was replenished at each tide, 

 until it became so extensive as to burst through the bank, and scoured every- 

 thing before it. Constant endeavours had been made, and in some instances 

 successfully, to improve the harbour by extending the piers, but, as had 

 been stated, very much yet remained to be done, to form a good harbour at 

 Dover. 



It should be remarked particularly iu the paper, that one of the leading 

 features in the worksat Ostia, was the construction of the moles upon arches, 

 below the line of the low-water mark, so that the moles afforded still water 

 for the vessels, while the arches permitted the alluvial matter to be carried 

 through by the current. The same system had been adopted at Pozzolana, 

 in the mole called Caligula's Bridge, in which concrete was used for the 

 building. Sir John Uennie was of opinion, that this system of construction 

 might be very advantageously adopted in many situations, and he had fre- 

 quently proposed it. At Carrickfergus he designed two solid Ijreakwaters to 

 keep off the run of the sea on the most exposed side, while from the shore 

 «t right angles to it, and pointing to the centre of the breakwater, an arched 

 mole would have been built, besides which vessels would lie, at all times of 

 tide ; the run of the shingle along the shore, would thus have been very 

 sUghtly impeded. 



The Italian harbours deserved very particularly the study of engineers. 

 The port of Genoa had been badly designed, and was constantly embarrassed 

 by the deposit in it. Ancona being situated on a promontory had less de- 

 posit. At Ravenna the harbour had been nearly destroyed. The port of 

 Venice was almost entirely kept open by dredging by manual labour, assisted 

 by the moderate rise of tide at particular seasons. In the Lagunes, the ac- 

 cumulation of alluvial matter was immense. A canal was constructed en- 

 tirelv round the Lagunes, with locks and sluices, to admit the fresh water 

 when clear, by which means a power for scouring was obtained, and the 

 channel was kept open. Civita Vecchia was principally indebted to its posi- 



tion for being preserved from the alluvial deposit, which was felt so severely 

 all along the coast. 



Mr Thokold was struck with the apparent similarity between the harbour 

 of Sandwich and that of ancient Ostia, both of which had failed from the same 

 causes; whereas Itamgate was, like Civita Vecchia, an instance "fthe ad- 

 vantage of a proper selection of a site for a harbour. The port of Duhlm 

 might he also instanced as another example of comparative failure ; whila 

 that at Kingstown was altogether as successful, as he believed it was almost 

 entirely free from sand. The svstem of scouring away accumulations of 

 sand and silt from harbours, by means of large reservoirs, did not appear to 

 be sufficiently resorted to. Mr. Thorold was of opinion, that in some cases, 

 great advantage would result from the application of the steam engine and 

 the fla>h wheel, for raising water into tne scouring reservoirs. In the fens 

 of Lincolnshire, and near Yarmouth, he had found that arrangement of ma- 

 cninery verv economical for draining. It had been applied in the river cuV 

 tine of the Yarmouth and Norwich railway, after it had been partially filled 

 bv a storm. The cutting was about half-a-mile in length, 100 feet wide at 

 tl^e top, and 20 feet in width at the bottom, and was 10 feet in depth. It 

 was completely drained in 36 hours, with an expenditure of oidy o tons of 

 coals. A reservoir of those dimensions would be found a great assistance tor 

 scouring a harbour, when any extra accumulation had occurred. 



ANCIENT DECORATIVE ART. 



At the Archsological Institute was read the following interesting paper 

 on the varhus Audent Dicorulive Arts and P.ocess of Working m Metals, 

 such a. Chasing, Embossing, Niello, Filagree, Ifc. By Mr. Hcusos Tim- 



NER. 



The paper contained rather a general view of the subject than details 

 respecting the several processes in metallurgy anciently used. The writer 

 observed that in the m^ijority of instances we can now show scarcely more 

 iban the names wherel)y numerous artificial processes connected with 

 workin<r in metals during the mediaeval period were designated, in evidence 

 of their having been practised. The variety, however, of these distinctive 

 appellations rendered it desirable that a catalogue of the descriptions 

 w'hereb) they were distinguished in commercial traffic should be formed, 

 in order that distinctive names, as yet unintelligible, may be appropriated 

 to the several objects of curious workmanship exhibited from lime to time. 

 To the British antiquary it would be an attainment of great interest it his 

 researches enabled him to identify the method of working lo gold or silrer 

 lised at an early period in this country, and known by reputation la 



oiher parts of Europe as the work of England, opus An^licum. and a va- 

 riety of it familiarly designated as the work of Durham, opus Dunulmeiist. 

 It would be equally desirable to be enabled to classify such examples of 

 foreign workmanship as may be found iu our island by their proper desig- 

 natio'ns • as the work of the Saracens, opus Saraeeiiorum,-or the opus 

 Gra:cum,-lhe opus Veneticum, work of Venice,— the work of lours, opus 

 Turonense,—or of Cyprus, opus Cyprense. Any attempt towards such a 

 classification would possess more than a merely curious autiquanaD in- 

 teivst ■ since it could not fail to throw important light on the history of 

 commerce and international relations in early times. Moreover, the extent 

 to which objects of personal ornament and productions of a costly charac- 

 ter were used in a country afforded valuable collateral evidence of the 

 actual state of society. It is obvious that any considerable mtroductioa 

 of foreign luxuries during the infancy of commerce must have b>-en the 

 result of some influential circumstances by which ilie taste of the time vvas 

 fixed or modified ; and therefore the prevalent esteem for any particular 

 objects of foreign production may be taken as evidence of commercial and 

 friendly relation at that period. The elevation of an ecclesiastic of Greek 

 origin, Theodoras, to the see of Canterbury, in the seventh century, must 

 hav'e tended to the introduction of the arts and choicer productions of 

 Greece or Asia, as well as of the dogmas or ceremonial peculiarities of the 

 Eastern Church : and it was in sacred ornaments that the most costly pro- 

 cesses of art were lavishly displayed. The practice of performing pil- 

 erimacres lo Rome, the Holy Sepulchre, and other remote placrs— where 

 the rich produce of various countries was displayed to view, and an em- 

 porium opened for the supply of the most remote regions of Christiaa 

 Europe— doubtless led to the introduction of numerous works of foreign 

 artificers into this country. By such pilgrimages, even more perhaps than 

 by commercial trallic, were the productions of Italy, Greece, or the tast, 

 imported into our country in earlier times. , . ,i, 



Mr Turner observed that we have scarcely any data in regard to the 

 actual practising of the more curious processes of metallurgy, either by 

 foreigners or natives, in England, in very early times. It may be reason- 

 ably surmised that the most precious existing example of go dsraiths 

 work— the Alfred Jewel, preserved at Oxford-was fabricated in this 

 country ; though some antiquaries consider its enamel as of oriental work, 

 while the gold^ettiug, richly elaborated in filagree, may doubtless be Eng- 

 lish However, it was to be remembered that, whilst the art was chiefly 

 subservient to ecclesiastical purposes, it was also chiefly practised by ec 

 clesiastics ; and that throogh their communication with their foreiga 

 brethren, the knowledge of curious artistic processes would be diflused 

 throughout their order, and carefully preserved. Thus, the arrival of some 

 Greek acolyte with Archbishop Theodorus aflofds a reasonable ground for 



