1849. 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



239 



Nemours; sulisequently Rondelet used it for the paving of the 

 Pantheon. The Barriere de I'Etoile is faced witli it; tlie pedestals 

 of the Pont d'Jena, the large basins of the Chateau d'Eau, and of 

 the foundation of the Innocents, and the parapets of the terre- 

 plein of the Pont Neuf are executed of this stone, as are also the 

 steps, parapet walls, and balustrades of the church of St. Vincent 

 de Paul. 



The specific gravity is 2'605; its weight about 163 lb. Eng. to a 

 foot cube; and it is able to resist a crushing weight of 332 kilo, 

 per centimetre square. 



The lias, which was formerly extracted to the south of Paris, 

 was an excessively hard stone, but the quarries are nearly ex- 

 hausted. The name is still retained amongst the quarrymen, and 

 is by them applied indiscriminately to the liardest beds of calcaire 

 grossih-e, which rarely occur in any great depth. At Arceuil, Ba- 

 gneux, Montronge, &c., the lias is fine-grained and compact, but is 

 rarely raised in blocl<s of more than a foot thick. At Montereau 

 it is occasionally 2 feet thick. At St. Cloud, it is soft; at Maisons, 

 in the south-west of Paris, it takes a rose tint, and occurs in beds 

 of from 9 to 10 inches thick. The specific gravity of the lias is, 

 on the average, 2-+39; the foot cube weighs 15211).; the crushing 

 weight per centimetre square is even greater than that of the 

 Chateau Laudon; it is 4+5 kihig. It was doubtless for this rea- 

 son that it was chosen for the execution of the columns of the ex- 

 terior of the Madeleine and of the Bourse. The crown moulding 

 of the large pediment of the Louvre is executed in lias, extracted 

 at Mendon; it is of two pieces each 16 m. 24 c. long, by 2 m. 60 c. 

 wide, by 46 c. high (53 ft. 3 in. X 8 ft. 6 in. X 1 ft. 5 in.) 



The "cliquart" extracted at Vangirard and Mendon is a species 

 of lias of a rather looser texture. 



The stones called the "roches" are hard, of a coarse grain, 

 very shelly. They occur in beds varying in thickness from 1 ft. 

 4 in. to 2 ft. 2 in.; their specific gravity is between 2-415 and 2-305, 

 the heaviest being, as usual, the best. The foot cube weighs be- 

 tween 151 lb. and 141 lb.; the crushing weight 302 kilogs. and 

 283 k. p. c. square. The roche of St. Cloud is red and shelly, but 

 of a very superior quality; it occurs in beds from 18 inches to 

 2 feet thick, and has the peculiar quality of being able to be em- 

 ployed on the wrong way of the bed. The isolated columns of 

 the court of the Louvre and of the garden front of the Tuileries 

 <ire of this stone, and have stood well for upwards of 200 years. 

 We shall have occasion to revert to this apparent anomaly on 

 some future occasion. The basements of the Madeleine, St. 

 Vincent de Paul, Notre Dame de Lorette, of the Palais du Quai 

 d'Orcay, and of the Bourse, are executed in the "roche de Ba- 

 gneux." 



The bridges of Neuilly, the Pont d'Jena, of Louis XVI., and 

 numerous similar constructions, are built of the "roche" of Saillan- 

 court. At Rouen large quantities of the roche of Cherence are 

 employed in woiks which require solidity: for instance, the stone 

 bridge and the basement of the Custom House. The rubble filling 

 of the bridge is, however, of the Vetheuil stone, one of the lowest 

 members of the tertiary formations. At Havre, the plinth of the 

 Museum is executed in the Cherence stone. The practice of the 

 French architects is never to employ the softer materials, such as 

 the Caen oolite, near the ground. 



The "pierre franche" is a fine, close-grained stone, less dense 

 and hard than the "roche," but preferable for the decorative pur- 

 poses of architecture, on account of the superior homogenity of 

 its grain. Its specific gravity is about 2-130; the foot cube weighs 

 1331b. nearly; the crushing weight is about 126 kilogs. per centi- 

 metre. The lower parts of the Pantheon are of this stone, ex- 

 tracted at Arceuil. The angle stones of the facade of the same 

 building are executed in blocks from the banc royal of Conflans, 

 of the same nature; they were 10 feet square by about 6 ft. 6 in. 

 high, and weighed about 24 tons. The arches of the portico and 

 of the interior of the church and the dome, the entablature, and 

 the capitals of the exterior order, are of the same stone. The 

 Vergele'e and the St. Leu are of the same category, as is also the 

 stone of rile Adam; they are extensively used in Rouen and the 

 neighbouring cities, on the banks of the Seine and the Oise, in 

 those of the canal, and on the Northern Railway. The exterior 

 dome of the Pantheon is in Ver'gelee stone. 



The lambourde is a soft stone of an even, coarse grain; it de- 

 composes when exposed to moisture, and is therefore only used in 

 positions in which the action of the atmosphere is the slightest. 

 The best stone of this description is extracted at St. ]Maur, where 

 it reaches 1 ft. 8 in. in thickness. Some beautiful stones for inter- 

 nal works are obtained in this series of Conflans and at St. Leu, 

 which attain 2 ft. 2 in. thickness. Tlie specific gravity varies be- 

 tween 1-897 and 1-709; the weight per foot cube is between 1131b. 



and 107 lb.; the crushing weight is about 59 kilogs per cent, 

 square. 



The chemical type of the building stones of Paris may be re- 

 garded to be that of the stones found near Marly; they are thus 

 composed — 



Carbonate of lime 89 



Magnesia 1 



Silicate of ammonia 10 



lll'J 



Sometimes the magnesia disappears, and the quantity of clay and 

 flint diminishes considerably: thus it is — 



Carboiiule of lime O'DMS 



Silex and clay 0<il5 



l-OtO 



At Vernon, in the department de I'Eure, a species of indurated 

 chalk is largely quarried for local uses. The church of Vernon, 

 and that of Louviers, are executed in this kind of stone, as are 

 also those of Pont de I'Arche, and of les Andelys, When fresh 

 from the quarry these stones are soft, but they harden by exposure 

 to the atmosphere; so much so as to resist atmospheric action in a 

 very extraordinary manner. In the instances of the three first- 

 named churches, all the external ornamentation is of the most 

 elaborate character of the "flamboyante" architecture; and in all 

 cases where the water does not lodge, the details of the foliage, 

 and the arises of the mouldings are preserved in a very remark- 

 able manner. The blocks are sometimes 3 ft. 4 in. high, their spe- 

 cific gravity is 2-155; the foot cube weighs 135 lb. nearly, the 

 crushing weight is about 220 kilogs. per centimetre square. 



The most correct chemical analysis of the chalk in the depart- 

 ment of the Lower Seine was made upon some extracted at St- 

 Catherine. It is more fissured than at Vernon, St. Etienne, or 

 Caumont, but may be regarded as of the same mineralogical type. 

 It contains — 



Carbonate of lime C'S 



Silicate of ammonia 12 



.Sand () 



Oxitte of iron 2 



Water 12 



luo 

 A similar description of indurated chalk is extracted at Caumont, 

 in the Seine Inferieure, to the north-west of Rouen. This, or a 

 like stone from St. Etienne, nearer still to the town, was much em- 

 ployed in the middle ages in the buildings of Rouen. The cathe- 

 dral, St. Ouen, St. Maclou, the Archbishop's palace, may be cited 

 as instances. 



The lateral elevations of the Madeleine are of the Pierre Franche 

 of rile Adam, the upper parts of St. Vincent de Paul, of N.D. de 

 Lorette, of Vergele'e de St. Leu; those of the Palais du Quai 

 d'Orcay, are a mixture of the pierres franches of Carrieres St. 

 Denis, Montesson, and Carrieres sous Bois, near St. Germain. 

 The fa.ades of the Bourse are in stone of I'lle Adam and of Conflans. 

 The restoration of the Palais de Justice, the completion of St. 

 Ouen, the upper parts of the Douane and of Entrepot des Sels, at 

 Rouen, are in Vergelee de St. Leu. 



At Havre, and generally in the embouchure of the Seine, the 

 calcareous stone of the Calvados are used. An examination of 

 them would lead us into too many details at present; but they have 

 become so interesting to us, from the extensive use made of them 

 in England, that it is much to be desired that a more elaborate 

 examination be made than we have at pi-esent. The notices con- 

 tained in T/ie Builder, notwithstanding their undoubted merit, 

 present questionable points. The chemical analysis, firstly, I am 

 convinced, is not correct; inasmuch as the Caen stone is stated 

 only to contain a trace of magnesia, whilst it is notorious that the 

 lime it yields is thin, without being hydraulic, which would not 

 occur unless there were present a verj*considerable quantity of 

 magnesia. The use of the franc banc is justly objected to, but the 

 use of the stone from the quarries of la Maladrerie is much more 

 dangerous, and this, I observe, is sent over to London in very 

 large quantities. It is, if not asserted, at least given to be under- 

 stood, that no inconvenience would arise from the use of Caen 

 stone placed the wrong way of the bed; whereas all the most ac- 

 curate and scientific observers who have made any researches into 

 the subject — -namely, Rondelet, Soufflot, Peyi-onnet, Ganthey, 

 Sganzin, Reibel, and Vicat, — all agree in asserting that the re- 

 sistance of stones is much greater when they are employed upon 

 their natural bed. As to the action of the sea water upon the 

 Caen stone, it is universally received amongst the French practical 

 masons that the sea water destroys it very rapidly; and chemistiy 

 teaches us that the nmriates and sulphates of magnesia, present 

 in the sea water, enter into energetic combination with the salts 

 contained in the limestones, and produce rapid disintegration. 



