1S47.J 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



81 



ance had reached its utmost limits, and, if any improvement was to be 

 obtained, it was requisite to obtain it from a difl'erent source. In the race 

 of improvement, the stage coaches were not behind the mails ; and we 

 have only to mention the Brighton, Oxford, Cambridge, Southampton, 

 Shrewsbury, and other coaches, to prove that the system was carried to 

 the highest degree of perfection of which it was capable.* In 1821 there 

 were 24,581 miles of turnpike roads in England and Scotland, and 8,000 

 miles in Ireland ; and since 'hat time they have much increased. 



Paving. — When the turnpike-road system was introduced, the pavement 

 of the metropolis was improved by tlie substitution of square blocks of 

 granite, in place of the rounded boulders, or large irregular pebbles, which 

 had been previously used. Blocks of granite of various dimensions, have, by 

 way of experiment, been laid on concrete, with the joints grouted with lime 

 and sand, in order to insure the greatest stability amongst the blocks. 

 M'Adam's system was introduced in some streets where the traffic was light, 

 but it did not equal the granite paving. Wood blocks in different forms, 

 hexagonal prisms, or cubes, or rhomboids, with the grain placed vertically, 

 or nearly so, have been introduced for paving, the blocks being either con- 

 nected by wooden pegs, or merely laid upon a bed of concrete. This system 

 was borrowed from Russia, and patents have been taken out Ijy Stead, in 

 1839, and many others, for different forms of the blocks ; it has the advan- 

 lage of diminished ncise and friction, but its great defect is that of being 

 dangerously slippery in particular states of damp weather, and it appears in 

 consequence likely to be abandoned. Asphalte, a natural brittle, bituminous 

 substance, found in volcanic districts, was introduced from France for foot 

 pavements, in 1S36 ; it is brought to a semi-liquid state by heat, then mixed 

 with sand and gravel, and spread over a bed of concrete, and wheu cold, 

 forms a compact and durable pavement. Flats, or flat gritstone paving- 

 blocks have been used in larger blocks, and better laid, so that paving has 

 been improved; the great difBculty, however, in keeping it in order in Lon- 

 don and great towns, is occasioned by its being constantly broken up, to lay 

 and repair the numerous gas and water-pipes ; and it is desirable that sepa- 

 rate tunnels or subways should be employed for receiving them, as was sug- 

 gested by Williams and others, a few years since. 



* The transport of goods was equally defective as to speed, and was comparatively as 

 costly as that of passengers; at times, goods were Horn four to five weekd, aud seldom 

 less than thirty-six hours in going from Liverpool lo Manchester, at a cost of forty shiU 

 lini?s per ton ; whereas at present they are conveyed in three or four hours, for three 

 shillings per tou. 



CTo l/e contimied.J 



PROCESSINGS OP S3SENTIPIC SOCIETIES. 



SOCIETY OF ARTS, LONDON. 

 February 3.— W. F. CooKi;, Esq., V.P., in the Chair. 

 Mr. DiGBY Wyatt read an Essay " On the Art of Mosaic, Ancient and 

 Hodeni." — The author commenced by stating that the most cursory glance 

 at the subject must convince that this art, taking the form of either pave- 

 ment or mural decoration, has been connected with most of the noblest efforts 

 of architectural genius at all ages ; and as it is the wish of many at the present 

 lime to effect the revival of this art, he would endeavour to convey as clear 

 an idea as possible of the nature, history, and condition of this graceful 

 handmaid to the science of decoration. — The first positive notice of the ex- 

 istence of such an art occurs in the 6th verse of the first Chapter of the Book 

 of Esther, wherein an account of the riches and luxury of the Palace of 

 Ahasuerus is mentioned, and that passage clearly establishes the fact that 

 the Persians were acquainted with the art, and it is supposed communicated 

 it^ to the Greeks, from whom the Romans obtained their first specimens. 

 Ciampini divides the art into four principal varieties, called tesselatum, sec- 

 tile, figlinum, and vermiculatum. The first, the opus tesselatum, probably 

 the most ancient ; this kind of mosaic consisted of small cubes of marble, 

 seldom averaging more than J of an inch square ; the best specimens of this 

 description of tessela occur at Pompeii, in the Vatican. The second division 

 of the art, the opus sectile, was also applied to pavements, and it is in this 

 description of mosaic that the simple yet magnificent pavement of the Pan- 

 theon at Rome is executed. This variety of mosaic was formed of thin 

 slices of different coloured marbles, cut into slabs of a given form. The opus 

 figlinum was more generally employed in mural decoration, and according 

 to Pliny, was first used in the decoration of the baths of Agrippa, behind the 

 Pantheon ; it consisted of figures, fruits, ornaments, &c., by means of small 

 cubes of vitreous composition, composed of allumine and some metallic oxide 

 to colour it. No specimen of this description of mosaic has ever been dis- 

 covered in England. The fourth description of mosaic, or opus vermiculum, 

 is subdivided by Ciampini into three varieties. The opus major generally 

 employed in large pavements or ceilings, to represent the figures of gods, cen- 

 taurs, &c. The opus medium was a much finer kind of work, and was gene- 

 rally applicable to walls. The third division, opus minor or opus vermicula- 

 tim, was the finest and most elaborate of all the ancient Roman mosaics, and I 

 consisted of the most delicate patterns, formed entirely by mosaic pieces of 

 marble and fictile work, many of the stripes being only the 20th of an inch ■ 



across. The most beautiful specimen that has been presented to us is the 

 one usually known by the name of Pliny's doves (a copy of which in mosaics 

 was exhibited). There is one kind of mosaic which the author has observed 

 in Pompeii, and which he considers may not be inaptly termed the opus un- 

 certain of mosaics, composed of all sorts and kinds of marbles put together in 

 singular shapes, and when united into a mass with cement and laid on the 

 floor prepared to receive it, it is reduced to a polished face by friction. In 

 completing the sketch of this art under the Romans, the author stated that 

 the preparation ordinarily made by them for the reception of the mosaics, 

 consisted in their first placing a layer of large stones or flints, but with very 

 little cement, on the ground; upon this was placed acourseof concrete com- 

 posed of smaller stones and lime beaten and rammed with great care ; upon 

 this a third layer of cement was placed, the lessara; or mosaic were then 

 placed, and over the whole was poured liquid cement, to perfectly fill 

 up the interstices between the cubes. — During the reigns of the twelve Ca:sars 

 this art rose to an unexampled popularity ; during the reign of Hadrian, 

 (a.d. 138) to that ofCaraculla, the arts appears to have lost in quality ; after 

 the year 220 it became obscured by the clouds which swept the Roman em- 

 pire. 



From the time of Constantine three varieties arose, which obtained univer- 

 sally in Italy from the 4th to the Hth century, and during nearly 1000 years 

 changed but little either in principle or design. Tlie Emperor Alexander 

 Severus (a.d. 222 to 235) brought with him from Alexandria great quanti- 

 ties of porphiry and sepentine, which he caused to be worked into small 

 squares and triangles, and variously combined, thereby laying the foundation 

 of this art which formed the pavement of all the rich Italian churches. We 

 have an interesting specimen in Westminster Abbey referred to the vear 

 1260. 



The author, after tracing the history to its decline, and giving some 

 account of the encaustic tiles, proceeded to state the circumstances which 

 had of late years led to its partial revival ; he also gave a detailed description 

 of the processes of manufacture employed by Messrs. Singer and Pether, 

 and Messrs. Minton and Co., and concluded by urging on architects and the 

 public generally the applicability of the manufacture to the purposes of de- 

 coration. 



The meeting adjourned after passing a unanimous vote of thanks to Mr. 

 Wyatt for his communication. — The rooms were filled with beautiful speci- 

 mens of ancient and modern works of art in mosaic. There were some fint; 

 Florentine mosaics contributed by Mr. Brown ; modern glass mosaics of ex- 

 quisite workmanship executed by Mr. Pether and Mr. Singer; encaustic tiles 

 by Mr. Blashfield ; mosaic tesserfe by Messrs. Minton ; and a large collection 

 of elaborate coloured drawings contributed by Mr. Blashfield, Mr. Wyatt, 

 and Mr. Owen Jones. 



ROYAL SCOTTISH SOCIETY OF ART.S. 



Jan. 25.— David Maclagan, M.D., F.R.S.E., President, in the 

 Chair. 

 The following communications were made : — 



" Description uf Pottery made by the Ojibbeimy Indians, with an < 

 of a Chemical Analysis of fragments of it." By John Macadam, Esi 



account 

 Esq. 



The Pottery exhibited before the Society, and referred to in Mr. Maca- 

 dam's paper, was obtained from the neighbourhood of Peterborough, Cana- 

 da West. It is of a brownish black colour, the outer surface being reddish 

 It is exceedingly hard and difficult to fracture. The vessel is ornamented 

 around the edges with a design evidently copied from nature, and some- 

 wliat resembliug a pinnate leaf, besides which the surface is almost totally 

 covered with a scratched-like net-work ; indeed, the design as a whole re- 

 sembles much that which exists on the pottery occasionally found in the 

 Druidical tumuli of our own country. There are small crystal-like parti- 

 cles distributed throughout its mass, which vary in size from one-fiftieth to 

 one-twentielh of an inch in diameter. These particles are pure silica, and 

 were probably obtained by pulverising quartz or some other natural variety 

 of silicic acid. The pottery also contains organic matter to a considerable 

 extent, which is of vegetable origin, and was added, no doubt, to this with 

 the same intention as straw was added to the Babylonian and Egyptian 

 varieties of sun-burnt pottery, viz., lor the purpose of increasing tlie adhe- 

 siveness of the panicles. A portion of the pottery submitted to chemical 

 analysis gave the following results : — 



Water .. .. .. 1S5 



Organic matter . . . . 5 92 



Silicic acid .. .. ,. 64-80 



Sesqui. oxide of iron . . . . 14';i0 



Alumina .. .. .. 9-95 



Lime .. .. .. 4 39 



Magnesia .. .. .. 1*43 



Potash and Soda . . . . traces. 



The amount of oxide of iron stated is rather high, as the iron present 

 though calculated as the sesqui-oxide, does not exist as such in the pottery 

 but is there, almost totally, as the protoxide, except in those parts of the 

 pottery which possesses a red colour. 



From the resultsof the investigation made on this interesting piece of manu- 

 facture, some conclusions were drawn to the following eflTect : First, that 



the poltery had probably not been made by the use of any one material 

 found native, but was manufactured from a mixture of pulverised silica, 

 ferruginous clay, and organic matter ; secondly, that the heat employed for 

 baking the pottery, when made, was one of no high temperature, as, had it 



12 



