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HISTORY OF ENGINEERING.
Rook I.
enormous thickness ; the conical vault has disappeared, and the interior, when the writerwas at Rome , was fitted up with seats to form an amphitheatre, where hull-fights wereoccasionally exhibited. In the views given by Pietro Santi Bartoli , in his work on the se-pulchres of Rome , &c. the entrance and outer walls are shown.
The Tomb of the Scipios , discovered in 1780, in a garden to the left of the Appian Way ,near the gate of S. Sebastian, is one of the most ancient: it is cut out of tufa, and consistsof a series of dark chambers, in one of which is the sarcophagus of L. Scipio Barbatus, thegreat-grandfather of Scipio Africanus , who was buried, it is supposed, at Liternum, about565 years after the building of the city, according to Livy .
The Pyramid of Cuius Cestius, which stands near the gate of St. Paul, is partly withinand partly without the walls ; its height is 121 feet, its breadth at the base 96 ; it is con-structed of white marble, probably from the quarries at Luna. It contains a room about20 feet by 16, and 17 feet high, upon the walls of which are some paintings, representingtwo females sitting, two standing, with a victory between them ; there are also vases andcandelabra. Pliny , lib. xxxvi. cap. 13., tells us the tomb of Porsenna was of a pyramidal form,although the Greeks and Romans seldom used this figure.
From an inscription in the Museum Capitolinuin, found near the monument of C. Cestius,we learn that five persons were named heirs by his will, and that Pontius Claudius Melaand Pothos erected this pyramid.
Trajan's column was a monument to that emperor, or rather of his victories over theDacians . Apollodorus is supposed to have been the architect to whom its constructionwas entrusted, about the year 115 of the Christian era. Dion Cassius states that Trajanhimself erected it the year before he set out for Parthia ; but from the inscription on it,it would appear to have been raised by the senate and Roman people, when Trajan hadfor the seventeenth time the tribunitian power, which happened the year the emperor wasabsent from Rome . Trajan died at Seleucia; his ashes were brought home, and depositedin a golden ball, on the summit of the column, which was contrary to the usual customof allowing a burial within the walls. The pavement from which this splendid marblecolumn rises is 15 feet below the ordinary level of the streets, the ground having accu-mulated since its foundation on all sides.
Engineers at the present day are astonished at the simplicity of its construction, and thedimensions of the blocks of marble that compose it. Die column is nearly perfect; itspedestal consists only of seven blocks ; the cornice is a single piece 20 feet square, and 6feet 4.} inches thick. Die shaft of the column is composed of nineteen courses, each 5feet in height, and the entire diameter ; in the centre a newel is left, around which are cutthe stairs that conduct to the summit. Die capital, or last of the nineteen blocks of theshaft, is 14 feet square, ornamented with eggs, well sculptured, under which are indicationsof doric flutings. Die shaft is covered with spiral revolutions of sculpture, representing infull relief the various exploits of the emperor.
The height of the pedestal is 17 feet 11 inches ; that of the shaft, capital, and base, 97 feet9 inches, and the ancient part of the pedestal remaining above 9 feet 6 inches, making a totalheight of 125 feet 1 inch.
The lower diameter of the column is 12 feet 2 inches; the upper 10 feet 9 inches.One hundred and eightv-two steps conduct to the gallery formed above the abacus, onwhich rises the pedestal that supported the statue of the emperor, as some of his coins show.
Two thousand five hundred figures are sculptured on this beautiful monument, amongwhich the emperor is represented more than fifty times ; the figures are 2 feet in height atthe bottom of the shaft, and increase as they mount or get farther from view, being at thetop nearly 4 feet.
Antoninus Pius also had a similar column dedicated to him by Marcus Aurelius . Dieheight of its present pedestal is 26 feet: the column witli its capital and base consists of19 blocks of white marble. It is in height 97 feet 3 inches, with a pedestal above 6 feet inheight: the lower diameter is 13 feet 2 inches ; a similar staircase conducts to the summit,and a spiral decoration, like that of Trajan’s, winds round the outside ; but the subjects arenot so well sculptured.
Both these columns arc admirably executed, and interesting to the civil as well as mili-tary engineer for the attempts made by the sculptor to represent the various bridges, ports,ships, fortifications, implements used to destroy as well as protect; both have been ad-mirably engraved, from casts taken from the columns when scaffolding was erected aroundthem to hoist the present statues of St. Peter and St. Paul, which now terminate them ;the author also measured them, and their dimensions are more fully given in the “ Antiqui-ties of Rome.”
The Mausoleum of Adrian, on the other side of the Tiber , apparently was intended torival that of Augustus : it had three stories resting on a square basement. Procopius informs us that two stories were decorated with columns and statues, and at the top was thestatue of Adrian. “ The tomb," he says, “ of the emperor stands without the Porta Au-relia, at about a stone’s throw from the walls, and is well worth a visit, for it is built ofParian marble ; the stones with which the basement is constructed are joined alternately to