Chersiphron & Son Engineers

"A marshy soil was selected for its site, in order that it might not suffer from earthquakes, or the chasms which they produce. On the other hand, again, that the foundations of so vast a pile might not have to rest upon a loose and shifting bed, layers of trodden charcoal were placed beneath, with fleeces covered with wool upon the top of them. The entire length of the temple is four hundred and twentyfive feet, and the breadth two hundred and twenty-five."

Pliny seems to ignore that the site of the temple was more ancient and that the architects were rebuilding on it, therefore he guessed that a marshy soil was chosen for taking precaution against earthquakes. Unfortunately, this is not true, as the 1985 Mexico City earthquake had demonstrated. The epicenter was near Lázaro Cárdenas, 350 km away, but “in the marshy soil underlying the (Mexico) city centre, the destructive force of the earthquake matched that at the epicenter.” [5] Another problem of marshy lands can be the phenomenon of soil liquefaction. The soil, saturated by water, loses its strength during the earthquake shaking and behaves like a liquid [6]. The Latin naturalist describes that the architects obtained the consolidation of soil, necessary to have a proper basement for the temple, using some trodden charcoal. It would be interesting to check the mechanical properties of such a substrate, with respect to the seismic waves and soil liquefaction. Pliny is also telling that a layer of fleeces was used to cover the substrate of charcoal. We can try to guess a reason for the use of these fleeces: probably, the architects ordered to prepare this layer to have a sort of seismic isolation of the temple from the ground, allowing it to float on the soil during the earthquakes as a boat on water. This is, more or less, the same behavior of a modern anti-seismic building. The anti-seismic technology consists of installation of some isolators, which decouple the buildings from the ground [7]. Such isolators are cylinders consisting of alternate layers of rubber and steel bonded together, with a central lead core. The rubber layers allow the isolator to displace sideways, because they are very soft. However, the structure is very stiff vertically, because the layers of rubber reinforced by steel. These two characteristics allow the isolator to move laterally, and, at the same time, they can carry significant axial load. The lead core acts as a damper of oscillations. Pliny continues his description “Ctesiphon was the architect who presided over the work. The great marvel in this building is, how such ponderous architraves (epistylia) could possibly have been raised to so great a height. This, however, the architect effected by means of bags filled with sand, which he piled up upon an inclined plane until they reached beyond the capitals of the columns; then, as he gradually emptied the lower bags, the architraves insensibly settled in the places assigned them.”

In building the temple, people used the inclined planes to enable an easy work against gravity of huge masses. It is remarkable the use of bags filled with sand to set the huge stones. It is highly probable that ancient Egyptians had developed several techniques based on the use of sand to put stones and obelisks in their proper positions and that this technology had migrated within the Mediterranean region. The temple built by Chersiphron and Metagenes was destroyed by fire on 356 BC. The Ephesians rebuilt it, starting from 323 BC, larger and with more than 127 columns. The temple was so beautiful (we can imagine it as in Figure 2), that Antipater of Sidon, a poet who lived in the 2nd century BC, when compiled his list of the Seven Wonders, told [8]:

“I have set eyes on the wall of lofty Babylon on which is a road for chariots, and the statue of Zeus by the Alpheus, and the hanging gardens, and the colossus of the Sun, and the huge labour of the high pyramids, and the vast tomb of Mausolus; but when I saw the house of Artemis that mounted to the clouds, those other marvels lost their brilliancy, and I said, “Lo, apart from Olympus, the Sun never looked on aught so grand.”

Chersiphron then was co-author of the building of the marble temple with his son Metagenes. Besides the use of inclined planes and sand to set the elements of the temple, these engineers devised two interesting methods to move columns and architraves. Vitruvius in his “De Architecture” explains “the ingenious contrivance of Ctesiphon” to move the columns [9].

“When he removed from the quarry the shafts of the columns, … not thinking it prudent to trust them on carriages, lest their weight should sink the wheels in the soft roads over which they would have to pass, he devised the following scheme. He made a frame of four pieces of timber, two of which were equal in length to the shafts of the columns, and were held together by the two transverse. In each end of the shaft he inserted iron pivots, whose ends were dovetailed

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