142 MILITARY SCIENCES. 



machicolated battlements, and on the inside a raised breastwork ; the 

 towers had several stories, divided from each other by layers of beams and 

 connected by steps. The towers were so arranged also as to afford the 

 only access to the top of the wall. 



The walls of the ancient Falerii, in Etruria, which so long resisted the 

 Romans, and was first subjected 241 years before Christ, present the earliest 

 example of the true arch construction in the gates {pi. 42, Jig. 16), which 

 were flanked by two square towers. The key-stone of the arch is orna- 

 mented with a man's head. The wall itself is so entirely destroyed that 

 of the construction of the battlements, &c., not a trace remains. 



Far more perfect is the construction of the arch shown in the three 

 entrances of the Porta Veneris of Spello, in Umbria. This gate, of which 

 Jig. 10 is the plan andj^^. 11 the elevation, displays besides more architec- 

 tural decoration. 



Of great interest are the walls of Pompeii, as affording already an exam- 

 ple of a double and even a triple defence. PL 43, Jig. 10, gives a per- 

 spective view of part of these walls, as restored, for upon the exca- 

 vation of this city, which, as is well known, was buried during an eruption 

 of Vesuvius, 79 b. c, by a shower of ashes, they appeared as shown in fig. 

 13. Fig. 11 is a horizontal section of the whole structure just above the 

 surface of the earth ; fig. 12, a similar section through the upper story of a 

 tower; fig. 14, a vertical section through the wall; fig. 15, the same 

 through a flanking tower. The lower part of these walls belongs to the 

 most ancient constructions of this kind, and here for the first time water 

 conduits appear; these, however, as well as the second row of machicoles 

 above, and the terrace arrangements upon the towers, belong to a later 

 period, that of the wars between Caesar and Pompey. PL 42, fig. 18, is a 

 view of the gate of Pompeii which lies in the direction of the ancient Nola, 

 whence it took its name. This gate, which is restored in our repre- 

 sentation, was found completely destroyed in its upper part ; the arch con- 

 struction, however, was unmistakable. 



The walls of ancient Rome, dating from the age of Aurelian, form 

 still a part of the environment of Rome, and are remarkable for being 

 built of brick, whereas all the structures hitherto mentioned have been 

 of stone. PL 43, fig. 6, gives a view of the Capitoline hill with its 

 defences at the time of ancient Rome. Here also curtains of wall, 

 straight on the outer side, alternate with towers {fig. 7) ; on the inside, 

 however, the construction is different. Fig. 8 gives a perspective view of 

 the inside of the wall, and fi.g. 9 the horizontal cross-section, about seven 

 feet from the earth. From the views here given, and from the vertical 

 section through the wall {pL 42, fig. 19), it is seen that the rear part of the 

 same formed what was called a cavata, a vaulted passage, open on one 

 side, which was raised above the footway, and to which access was found 

 through the towers, while above this covered gallery the wall appears 

 terrace-formed. The towers, of which pL 42, fig. 20, shows the vertical 

 section, overtopped the walls considerably, and preserved by means of loop- 

 holes, a defence in line with the battlements upon these, while they had a 

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