18iO.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



355 



IMPROVEMENTS OF THE RIVER SEINE. 



Some very important works are in progress at present upon the 

 river Seine, for tlie improvement of tlie navigation of that river, a 

 succinct account of which is ajipended. 



The Seine has a very long devious course, principally through a 

 valley in the tertiary limestones of the I'aris hasin, and througli 

 the chall< between Mantes and the sea. It is very suhject to fldods 

 in the winter and spring, which come down from the hills of Hur- 

 gundy with considerable violence; whilst in the sonnner it is often 

 so loH' that, as in 18+'2, the navigation by barges drawing 1 feet 

 water is suspended. The tide runs to a little beyond Pont de 

 I'Arche, a distance of perhaps 6U miles. 



Owing to the configuration of the eiuboiicliure a bar is formed 

 at Quillebceuf and Tancarville, at a point w)iere the rivei- — which 

 had previously spread out on both sides over a flat alluvial plain, 

 .sometimes bare at high tides — is contracted l)etween two advancing 

 spurs of the chalk formation. Formerly the reijime thus super- 

 induced was such as to give rise to a "bore" of about 3 to 4 

 feet high occasionally ; but at neap tides there was never enough 

 water on the bar to allow a 40U tons' burden ship to mount the 

 fiver, although directly the stream became narrowed above 

 Villequier, sufficient depth to float even a 1000 ton ship existed at 

 high tides. 



The objects proposed then were to deepen the river so as to 

 allow large vessels to reach Rouen, and to establish such a system 

 of locks, &c. in the upper portion, as to ensure a constant depth 

 of 6 ft. 6 in. in the driest seasons as far as Paris. The works 

 already executed have succeeded most remarkably in the attain- 

 ment of these objects as far as they bore upon them. They are as 

 follows: — 



Tidal Portion. — Up to August, 1850, they had been confined to 

 the embankment of the river between Candebec to Villequier and 

 Quillebceuf, by means of rubble-stone embankments of a length of 

 18.000 metres on the right bank, and of 9600 on tlie left bank. 

 At the point where the works commenced the channel was made 

 300 metres (1000 feet) vvide; and it was augmented 10 metres in 

 a kilometre, or in the ratio ] : 100 to the embouchure. The concave 

 embankment was found to require twice as much stone as that 

 upon the convex side, the former taking 100 metres cube, the 

 latter 50 metres cube, per metre forward. 



The result has been to deepen the river 2'80 metres (a little 

 more than 9 feet). The "bore' has disappeared in the parts regu- 

 larised; the length of the duration of the flood tide increased one 

 hour; the still water, or dead tide, has also gained a quarter of an 

 hour. The flood would be sent much further up tlie country did 

 not the stone thrown to protect the feet of the piers of the 

 Manoir Bridge, on the Rouen and Paris Railway, act as a dam to 

 keep it back. It is probable that the result of the works in the 

 river upon this bridge will be to throw it down. 



The total cost of the embankments has been hitherto 2,310,000 

 francs, or 92,400/. sterling, being at the rate of 3 francs the 

 metre cube of stone in place. 



To complete the project, it would be necessary to execute above 

 Candebec and la Meilleraie 5,122 metres of embankment on the 

 right, and 8,700 upon the left shore. Below Quillebceuf it is pro- 

 posed to continue the channel through the sandbanks of the em- 

 bouchure, by the execution of 12,5-tO metres on the right bank, 

 «nd 9600 upon the left. 



Natural Water Course above Tides. — The system adopted for the 

 attainment of the depth required in this portion, has been to erect 

 a series of barrages or weirs upon the river, so as to divert the 

 water into the arm rendered navigable, and to leave an overflow 

 under the control of the locksman at the head of the pond or 

 reach. 



The weirs are formed according to the plan so successfully 

 applied by M. I'oire'e at Bezons, consisting of a series of wrought- 

 iron frames with wooden blades to close the openings, fixed by 

 hand; the %ving walls are in stone, and dressed off at a level to 

 alio IV any flood-water to overflow at 6 inches above the depth re- 

 quired in the lock, should any sudden flood come down by night. 

 The locks are made 120 metres long by 12 metres wide (100 feet 

 by 40 feet), and a fall of 2 metres, or 6 ft. 7 in. nearly. 



Originally it was proposed to form at least ten of these barrages. 

 The first is formed in Paris itself, and is actually in course of exe- 

 cution; the river is being inclosed to a width of 32 metres in the 

 narrowest part, beginning from the extremity of the Isle de la 

 Cite, and terminating at the extremity of " terre Plein" of the 



Pont Neuf. The wing walls of the dam are dressed off at a height 

 to secure 2'16 jnetres water; the barrage is meant to lieap them up 

 to 2'26 metres; Imt of course before arriving at this heiglit, some 

 of the blades would l)e draivn. Quay walls and roads, witii inclined 

 approaches from the upper level, are being formed; a large cul- 

 vert, 2-50 metres wide liy 2'50 metres from invert to key, is also 

 constructed to take otf the lateral sewers to a level below tlie 

 locks. These works are estimated to cost 200,000/. sterling. 



Connected with these works may be cited the lowering of the 

 roadway of the Pont Neuf, to cost 72,000/. The old arclies are 

 cut away where necessary, and replaced by new arches of an ellip- 

 tical form, tlie space between the new and old work, where any 

 exists, being filled-in w itli hydraulic lime concrete. The scaffold- 

 ing employed is very remarkable, being in fact a suspension scaf- 

 folding, hanging from the turrets on the piers of the bridge. 

 Indeed, it would be impossible to imagine how works could lie so 

 carefully, so perfectly, and so elaborately executed, as all these 

 are, unless by French engineers, working with government money. 



Other barrages have been executed at Bezons, Andresy, and 

 Vernon; one at les Poses, near Pont de I'Arche, is in course of 

 execution. Barrages are to he formed immediately at St. Ouen 

 Meulan; others are proposed at Suresnes, Maisons, Triel, and 

 perliaps others below Meulan. 



The barrage executed at Bezons, at a cost of 80,000/., gave a 

 sur-elevation of 1-20 metres ( t feet) at a distance of /i miles from 

 the locks, the fall of the river being on the average O'lO per kilo- 

 metre, or 1 in 10,000. The heaping-up of the waters by the 

 barrage of Andre'sy is felt in the Seine and Oise, at a distance of 

 20 kilometres, or 12^1 miles. 



At some future day 1 will send you drawings of the barrage of 

 Bezons, which will illustrate the very simple, but efficient means 

 employed ou this river, to canalise it completely. 



Southampton, Oct. 23rd, 1850. 



Geo. R. Burnei.l. 



PUBLIC WORKS AT ALGERIA. 



The East India Company have at length roused themselves 

 from the state of inaction they so long preserved in the execution 

 of railways and other commuications in their immense possession. 

 It is better late than never. But to enable your readers to com- 

 pare the conduct of a government managed under the direct 

 control of a representative assembly, with that of the anomalous 

 body known in India as the Coompanni Jehan, I have the honour 

 to inclose you a condensed statement of what has been done by 

 the French government in Algeria since their occupation in 1830. 



It is to be observed, that we are far from wishing to hold up the 

 colonial government of our neighbours as a model in all things; 

 but the care they have taken in the execution of means of commu- 

 nication between the different points of their still very precarious 

 possession, may well merit our serious consideration. 



In the report from the .Minister of War to the Legislative As- 

 sembly, in the spring of 1850, it is stated that, subsequently to 

 the occupation of Algeria, there have been executed in that colony, 

 at the expense of the mother country, no less than 3270 miles of 

 road; 18,959 acres of marsh lands have been drained; 278.0U0 yards 

 linear of irrigation channels; and 82,057 yards of main drains or 

 ditches; and 127,000 yards of aqueducts or water courses have been 

 constructed; 91,900 yards linear of street have been formed or 

 regularised in the divers towns; and nearly 32,000 yards linear of 

 sewers formed in them; barracks have been erected for 40,000 

 soldiers, and hospitals for 5000 invalids. The port of .Algiers has 

 been improved, and important works begun at several other points 

 on the coast. Churches for tlie Christian population, mosques for 

 the indigenous races, have been restored, and new ones built where 

 needed. 



The country in which these works have been executed is only 

 77,120,000 acres superficial (France itself being 131,966,525 acre's 

 nearly), including the Little Desert, which occupies above two- 

 thirds of the surface. The densely-peopled portions are the civil 

 territories of the Prefectures of Algiers, Oran, and Constantine, 

 whose total surfaces are only 706,902 acres. The population in 

 1848 consisted of 64,123 Frenchmen, 55,141 other Europeans, 

 mostly Maltese, Spaniards, and Sicilians. The diff'erent sexes and 

 ages are— men, 49.839; women, 34,937; children, 34,488. The 

 indigenous population is supposed to be three millions; and the 

 army of occupation 60,000 men. 



4;" 



