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THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[August, 



ence. The oak used in Paris comes principally from Champagne 

 and Burgundy; lately, however, the Prussian oak has heen im- 

 ported in consideralile (luantities. For large roofs, Dantzic and 

 other Prussian fir is used; but the architects pay such very low 

 prices that the best woods invariably are sent to England. Indeed, 

 tliere are few architects who seem to be able to distinguish the 

 Swedish from the Prussian timber, for in all cases I have noticed 

 that for roofing purposes the former is employed where the latter 

 is demanded by the specifications. Indeed, so small is the supply 

 of Baltic timber in France, that in I848, after tlie bridges over the 

 Seine had been burnt down by the mobs, it was impossible to find 

 .50,000 cubic feet in all tlie markets of Dieppe, Fecamp, Havre, 

 Rouen, and Paris. 



Norway timber is used largely for purlins, and for partition stuff. 

 The deals and battens imported are of the second and third qua- 

 lity; but as all the better class of joiner's work is executed in 

 wainscot, this becomes of less moment. Some of the French oak 

 is very beautiful, and admirably adapted for joiner's work; hut its 

 gradually increasing price, owing to the clearance of the forests, 

 renders necessary the importation of the German, or, as we com- 

 monly call it, the Dutch wainscot. Mahogany is only imported 

 for cabinet-making: its use for joinery, or for ship-building, is 

 almost unknown. Rosewood and ebony are also imported for 

 cabinet-makers. American timber, e. g., pine, spruce, &c., rarely 

 enters France, e.xcept for the purpose of making masts and spars 

 of ships; teak is totally unknown, as are the whole tribe of African 

 or Australian woods. 



France furnishes very beautiful poplar, ash, and beech timber, 

 which are much used in building. Almost all the slate battening 

 for provincial use is made of poplar; the ash serves for cart- 

 building and carriage- works; the beech is principally employed 

 for piles and gratings, &c., under water. The department of Cal- 

 vados furnishes some of the finest beech-trees I have ever seen. 



In practice the French architects are much behind our own as 

 far as carpentry is concerned. Tliere are, certainly, exceptions. 

 Some of the roofs in Paris are light, elegant, and strong, the 

 thrusts well balanced, the resistances most skilfully calculated; 

 but, as a rule, the scantlings are far too heavy, the framing clumsy, 

 the affectation of mathematical construction too glaring. Little 

 or no ])recautions are taken to prevent the decay of the timber 

 from the moisture of the walls; the wood itself is often used full 

 of sap, and thoroughly wet — an objection, by the way, which may 

 be made to carpentry in London, for we often see the wood taken 

 from the river, cut up, and placed in buildings long before it can 

 have dried. It is, however, to be observed with reference to the 

 heavy scantlings used by the French architects, that the price of 

 woodwork is about 25 per cent, higher with them than with us. 

 Motives of economy serve as vast incentives to scientific investi- 

 gations in all countries. 



V. Metals. — The metals used in building are iron (cast and 

 wrought), lead, copper, zinc, and some of their compounds. 



1 (n). The greater part of the cast-iron used in the valley of 

 the Seine is derived either from the mines upon the Belgian fron- 

 tier, from the province of Berri, or from England; the importa- 

 tion from our own country being principally for the supply of the 

 markets of Rouen, Havre, and the nortli-west of France. The 

 wrought-iron comes from Berri and Flanders, and there are some 

 scra])-iron factories at Paris and Havre. 



The great distance the iron has to be transported, and the dear- 

 ness of fuel, render its use in the prodigal manner we are accus- 

 tomed to, quite out of the question. At Paris cast-iron costs about 

 50 per cent, more than in London; at Havre it costs about 33 per 

 cent. more. Its use is therefore avoided as much as possible, the 

 more especially as wood and stone-work are so much cheaper than 

 with us. The French founders are, however, very skilful, and 

 some very remarkable works are to be met with in I'aris, executed 

 in cast-iron. The northern gate of tlie Madeleine, the fountains 

 and lamp-posts of the Place de la Concorde, may be cited as illus- 

 trations. 



1 ('*). The best commercial wrought-iron is that from the pro- 

 vince of Berri; but it is very unequal in quality, sometimes as 

 tough as our best Welch iron, at others as short as tlie very com- 

 monest Staffordshire, owing to the bad manipulation in the facto- 

 ries. The very high price of iron, also, prevents so much atten- 

 tion being paid to the details of its production as is the case 

 where its economy renders its use a matter of every-day necessity. 

 Indeed, the state of the ironworks in France is a singular illustra- 

 tion of tlie evils of the protective system. The manufacturers 

 have a monopoly; they fear no competition, and make a bad iron. 

 The public pays dearly, and therefore uses as little iron as possible. 

 Since railways have been in fashion, however, the use of iron for 



roofs has become more general, and there are in Paris certainly 

 some of the finest roofs in Europe. Amongst them may be cited 

 the roofs over the Entrepot reel des Marais, of the llalle aux 

 Bk's (in cast-iron), of the St. tiermains and Rouen Railway, 

 executed by M. Eugene Flachat. 



The plate-iron box-girders are at ])resent unknown; corrugated 

 iron is but of very recent introduction, nor do the French archi- 

 tects appear to approve much of it. 



Owing to the very high price of wrought-iron, the use of iron 

 wire for suspension bridges has been puslied to a very gi'eat extent 

 throughout France. There are upon tlie Seine many very remark- 

 able bridges executed witli this material, such as the bridges at 

 Triel, Gaillon, and Rouen. The iron wire is exposed to this in- 

 convenience, that with all possible care in the fabrication of the 

 chains, the separate threads cannot be drawn out to the full; the 

 chains, therefore, always stretch, and the platform of the bridge 

 necessarily sinks. Wire chains, however, bear a greater weight in 

 proportion to their sectional area tlian square bars, and are more 

 likely to be homogeneous in their strength. They avoid, more- 

 over, the necessity for the coupling-links, which, on the last sus- 

 pension bridges executed, augment the weight of the chain 31 per 

 cent, beyond that absolutely necessary, supposing the chain to be 

 of one piece. The surface of oxidation is greater for the wires 

 than for the bar-iron chains, nearly in the proportion of 40 to 1, 

 and this becomes one of the greatest practical objections, for not 

 only does it necessitate frequent painting, but it diminishes, in 

 time, the real strength of the wire cables. The practical strength 

 of these is found in fact, to be as 0~0 to I'OO of the theoretical 

 strength; after a few j'ears it falls to 0'66. The voids in the wire 

 cables, according to theory, should be to the solids as 0'1025 to 

 I'OOOO; in practice they are found to be 0'25 to TOO. On the sus- 

 pension bridges, the government engineers enforce a proof of 

 17 kilogs. per millimetre square of the sectional area of the iron 

 wire chains, to ensure a surplus of strength as a guarantee against 

 deterioration; on the bar-iron chains the proof is only 12 kilogs. 



A very beautiful bridge was erected at Suresnes, by M. Flachat,, 

 of hoop-iron bands to form the main chains, which answered re- 

 markably well. This application attained a sort of medium re- 

 sult, both as to cost and strength, between the systems hitherto 

 employed. 



'i'liere is a very beautiful adaptation of the use of the suspension 

 principle to roofing purposes in the Panorama in the Champs 

 Elysees, at Paris. The chains are of wrought-iron wire. 



2. Lead. — For building purposes, the bulk of the lead used is 

 imported from England, Spain, and America. It is dearer than 

 with us, consequently its use is not so general, zinc being generally 

 substituted for it. 'fhe use and modes of fabrication, wherever it 

 is employed, are precisely the same as in England. 



3. Copper. — France also draws the bulk of its copper from foreign 

 countries, at very considerable expense; its use is therefore very 

 much restrained in building. The only instance 1 know of its ap- 

 plication on a large scale is at the Halle aux Bles, which was 

 covered with copper in the year 1712, and I think at the Bourse. 



4. Zinc. — The high price of the two last-noticed metals KsMf 

 given rise to the use of zinc upon a very large scale throughout 

 France. It is imported from Belgium and Germany in very large 

 quantities, to tlie extent of 13,000 tons, worth 280,000/. Except 

 upon the borders of the sea, it stands well in France; for the at- 

 mosphere does not contain (as in England, where so much coal is 

 consumed) the carbonic acid gases which destroy zinc. On the 

 contrary, in the interior, an oxidation of the external face of the 

 zinc takes place, which prevents its decay. The roof of the 

 palace on the Quai d'Orcay, the Northern, and some parts of the 

 Rouen Railway Station, the Orleans Station, and a crowd of other 

 buildings, are covered with zinc, to the perfect satisfaction of the 

 architects. 



The sizes of the metals usually employed for roofing are as fol- 

 low: — Lead in sheets, 12 ft. 3 in. long, by 6 ft. liin. wide; the 

 thicknesses are either a full eighth, or a short 3-16th of an inch: 

 the first weighs 89 •rrrrrll'. per yard square; the second weighs 

 118 jjjf-lb. per yard square. The lap is generally made from 3 

 inches to 6 inches longitudinally. 



The sheets of copper are made 3 ft. 6^ in. long by 3 ft. 3 in.; the 

 thicknesses are 0-0021236 and 0-002452G of a foot, the respective 

 weights 13-ili;lb. and 17-15 lb. troy per yard superficial. 



'riie sheets of zinc are made 6 tt. 4 in. long by 3 ft. 2| in., the 

 thickness varying from a short ^':j to a very full -^; the weights 

 are respectively 17-15 lb.; 19-06 lb.; 20-80 lb. troy per yard super- 

 ficial. The sheets of less thickness than these are rarely used in 

 good buildings. Of late years, in the neighbourhood of Paris, 

 zinc tiles have been much used; they are made from 14 inches tu 



