1S47.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



103 



the materials. Various descriptions of stones were used, — the tufa 

 of a reddish liue, and of a volcanic jiroduclioti, niucli used for the in- 

 terior of walls, and[in reticulated and rubble walls; — pepperino, anotlier 

 stone much used, also of volcanic production, but harder, and resisting 

 the action of fire and the weather better tli;ai the tufa; — and tlie traver- 

 tine, a stone much used in public edifices, calcareous, hard, and of a 

 yellow tint. The most ancient edifices of Rome were constructed of 

 Albano stone, put together in squared blocks and united by metal 

 cramps; it was also used in conjunction with the travertine stone, 

 which from its greater hardness was used in those parts of an edifice 

 most liable to injury, as arches, architraves, cornices, &c. Marble of 

 various countries was also largely introduced in the public edifices of 

 Rome. The Romans devoted much attention to pavements, which — 



" When used for floors, were highly decorated, much attention being required 

 to prepare the soil to receive them, and to select the material of which they 

 were formed. When on the ground, it was carefully examined, and rendered 

 solid throughout, after which it was spread over with some dry material. 

 When laid upon a timber floor, walls were not buUt under it, but a space 

 left between it and the floor, that the drying and settling should be equal 

 throughout. Holm timber was preferred to oak, being less likely to split 

 and warp, and thus cause cracks. After the joists were laid, thin boards 

 were fastened down to them by two nails, driven through the edges of each, 

 which prevented their rising. Fern or straw was then spread over the whole, 

 to prevent the lime coming in contact with the timber, which would have 

 immediately caused it to decay. Over this was a layer of rubbish, the stones 

 of which were as large as would lie in a man's hand : on this layer the 

 pavement was afterwards laid. New rubbish required that every three por- 

 tions should be mixed with one of lime; and old, five parts to two of lime. 

 Wooden beaters were employed, which by repeated blows reduced it to the 

 thickness of nine inches. An upper layer, composed of three parts of pots- 

 herds and one of lime, was spread over this to a depth of six inches, on 

 which was laid the slabs of marble, stone, or tessera;, care being taken that 

 the whole should lie in a proper inclination : it was then rubbed otT, and the 

 joints or edges of the ovals, triangles, squares, hexagons, or other figures, 

 made perfectly smooth. After rubbing and polishing, marble dust was 

 strewed over ; then lime and sand run into the joints. 



Pavements in the open air had over the first flooring another layer of 

 hoards crossing them, properly secured by nails, so that the joists were 

 doubly covered. The pavement first laid was composed of two parts of 

 fresh rubbish, one of potsherds, and two of lime. After the first layer, a 

 composition was spread over it, pounded into a mass, not less than twelve 

 inches thick. The upper layer being spread, the pavement, consisting of 

 tesserEE, each about two inches thick, was laid on, with an inclination of two 

 inches to ten feet, to prevent the frost from injuring it at the joints : before 

 the winter it was saturated with dregs of oil. When great care was required, 

 the pavement was covered with tiles two feet square, properly jointed, having 

 small channels an inch in depth cut in the edge on each side. These, filled 

 with lime, tempered with oil, had the edges rubbed in and pressed together. 

 The lime in the grooves or channels growing hard, neither water nor any- 

 thing else would pass through. After this precaution, the upper layer was 

 spread and beaten with sticks ; over which, either large tesserse or "angular 

 tiles were laid with the proper incUnation." 



Mr. Cresy has given us some architectural descriptions of the pub- 

 lic buildings of Rome. Although they do not strictly belong to en- 

 gineering, the examples afford data for construction; — we have en- 

 gravings of the Basilica at Fano, lie Amphitheatres of Castreuse 

 and the Coliseum, 



For the purpose of covering in the arena of these amphitheatres, 

 and to protect the spectators from the rain or sun, a velarium or co- 

 vering was used: — 



" Lampridins (in Com. a Militibus, Classiariis) informs us that the ma- 

 nagement of the vela was left entirely to saUors, as they were more expert 

 in going aloft amidst ropes, and understood the tackle which regulated the 



spreading of it better than others. There can be no doubt that it required 

 considerable dexterity on the part of the engineer to keep steady an awning 

 containing 113,345 superficial feet, which would be required for the amphi- 

 theatre at Nismes, and for the magnificent Coliseum nearly 250,000 superfi- 

 cial feet, or more than double; the weight of which, at only one pound per 

 foot, comprising the ropes and tackle, would amount to 112 tons or there- 

 abouts. So vast a weight disposed and uphtld by tension alone creates our 

 wonder and admiration. 



At the level of the attic story are 120 projecting consoles, each having a 

 circular hole about 10 inches in diameter, corresponding with a circular mor- 

 tice of the same size, and 6 inches in depth, made in the projection of the 

 cornice of the second order. The upper opening of the hole in each con- 

 sole has externally a groove 2 inches in height, destined for an iron collar, 

 to which was attached a tie, which secured it to the wall of the attic at the 

 level of the top of the console : the holes which contained these have some 

 portions of the iron run with lead remaining. 



The whole of each console received a round mast, which, passing through 

 it rested in a hole sunk in the cornice below, the iron collar preventing it 

 from acting against the sides of the console and fracturing it. The masts 

 alone would not be sufficient to support the weight of the vela, extending 

 over an elliptical area, the axis of which, in one direction, was 436 feet, and 

 in the other, 331. To aid in the support, other posts were introduced through 

 mortices about 10 inches in length, placed opposite each console, at the pro- 

 jecting part of the moulding which crowns the interior of the attic; on 

 each side, 4 or 5 inches from the edge of the attic, are holes still containing 

 the lead which secuied the iron ties that held these latter posts in their 

 places. Under the mortice holes are others, 8 inches square, and 2 feet in 

 depth, made in the upper step of the attic to receive the second posts. The 

 two posts were afterwards securely braced. 



Over the centre of the arena was an oval covering, permanently fixed, 

 which in the Coliseum was ornamented with an immense golden eagle. 

 Round the edge of this oval covering was attached a large cable. 120 pair 

 of cords, of equal length, stretched from the masts on the exterior to this 

 cable, were worked by pulleys; thus forming as many compartments. Each 

 pair of cords was furnished with rings, to which the covering was attached, 

 so that it could he drawn backwards and forwards at pleasure. The whole 

 of these nere called the vela or velaria, and each single compartment vela- 

 rium. The distance between the ropes on which the velarium ran was 

 greater towards the attic than at the centre; consequently, to make the 

 velarium run freely on its rings, it was necessary that it should be of an 

 equal width throughout : when spread, towards the attic it was stretched, 

 whilst towards the centre it sagged, and formed as it were a fold. To pre- 

 vent the sun passing through the opening thus made by the sagging, an in- 

 ternal hanging was attached around the fixed permanent oval." 



The Romans devoted great attention to the construction of baths 

 which were generidly used by all classes of citizens. At one time, 

 there were more than 800 baths in Rome ; the most complete con- 

 tained six principal apartments, — 1st. TXe ^ji-oiy^triKm, for undress- 

 ing; 2nd. The Frigidarium, cr cold bath; 3rd. The Ttpidariitm, used 

 to prevent, by the temperate air which it contained, the dangerous 

 effects of too sudden a transition from the extreme of cold to that of 

 heat ; 4th. The Laconium, an apartment warmed by a stove, to send 

 forth a dry heat ; 6th. T/ie i?a/««««, or warm bath ; 6tb. The Eltotht- 

 sium, or Onctuarium, where the oils and perfumes used by the bathers 

 were kept. 



We now come to that portion of the work which may be strictly 

 considered as connected with engineering — harbours and buildings in 

 water. It will be seen by the construction of these works that the 

 Romans devoted vast talent to their formation and construction. 

 In our Journal for January last, we gave a highly interesting paper on 

 the Harbour of Ostia near Rome, by Sir John Rennie, together with a 

 plan of the harbour. We are now, through the labours of Mr. Cresy, 

 enabled to give engravings showing a section through Claudius' 

 Port, and the elaborate Pharos. 



SECTION TRBOUGH CLAUDIUS' PORT, OSTIA. 



