Trajan's Column Research Articles

Genesis and Mimesis: The Design of the Arch of Constantine in Rome

The Arch of Constantine in Rome marks the passing of the pre-Christian era in architectural terms, recapitulating imperial traditions while at the same time heralding a new consciousness. It pioneered modes of design that exploited recycled elements for the sake of effects and motives quite beyond purely pragmatic considerations. Long the subject of controversy, the monument is today the focus of a scholarly quarrel over the possibility that its superstructure once belonged to an earlier arch on the same site. This study refutes this hypothesis on the basis of considerations of technique and design, showing instead that its composition depended on the emulation of the nearby Arch of Septimius Severus. The connection between the two buildings is indeed as direct as that between Trajan's Column and its full-scale "copy," that of Marcus Aurelius, and it is possible to unravel the rationale behind the transformation of one arch into the other. Since the composition of Constantine's was in this way effectively resolved, the architect could concentrate on the adaptations necessary for accommodating the various sets of recycled components. And despite their heterogeneous character, the outcome was a project of singular coherence in terms of proportion and geometry. It was the product of a unitarian conception that promoted Constantine's ideological program in the realm of urban design, imperial iconography, and political and religious intent.

Juvenal, the Niphates, and Trajan's Column ("Satire 6.407-412")

Juvenal, the Niphates, and Trajan's Column ("Satire 6.407-412")

Building Trajan's Column

Building Trajan's Column

TRACES OF ANCIENT COLOURS ON TRAJAN'S COLUMN*

Recent restorations of Trajan's Column uncovered two marble fragments bearing traces of pigments, bright red (minium, hematite) in one case, and yellowish‐orange (minium, hematite, clay minerals) in the other. Both were applied to the marble surface on a plaster underlayer. The presence of an underlayer and of surfaces coloured according to subject tells us that the colours were applied deliberately. Although the use of minium plus hematite is confirmed by archaeological finds, there is only a good probability that the colours were applied on the column at the time of its completion.

The Politics of Perpetuation: Trajan's Column and the Art of Commemoration

The frieze on Trajan's Column has long been criticized for requiring the visitor to circumambulate the column to read it. By considering the Column within the context of Roman funerary monuments, I argue that the frieze's spiraling motion was designed to manipulate the viewer into a reenactment of ancient funerary ritual as it is described in literary sources. Furthermore, the Column functioned as a viewing station; the helical staircase inside its shaft cast the visitor into disorienting darkness, before thrusting him or her at the summit into dazzling sunlight, simultaneously presenting a dramatic vista that promoted Trajan as an accomplished general who restored Rome's self-esteem—and her coffers—through military victory. The Column's full and powerful impact, which extends well beyond the decorative frieze, can only be appreciated by understanding the ancient viewer's experience as he visited Trajan's tomb.

Transport Logistics Associated with the Building of Hadrian's Wall

The building of some 75 miles of massive curtain-wall, incorporating forts, milecastles, turrets and bridges, together with a further chain of forts, milefortlets, and turrets 32 miles long on the Cumbrian coast, represents an impressive civil-engineering undertaking by any standards. The fact that this was accomplished in a relatively short space of time on the remote northern fringe of the Roman Empire makes the achievement even more remarkable. Unfortunately, there is a lack of firm evidence for many aspects of the building of the Wall, so that it is impossible to assess precisely the scale of effort and organisational complexity involved in this operation. Many details of its original structure remain a matter for conjecture, since it has nowhere retained anything like its original height, and large sections of its length lie beneath buildings or roads, or have been destroyed by quarrying, cultivation, or the robbing of stone for construction. Alterations during the three centuries of Roman activity on the Wall have, in many cases, obliterated evidence of the earliest structural features. The actual source of much of the original building material is uncertain, so that transport routes and distances must remain a matter for debate. There is little archaeological record of Roman transport methods, and depictions of vehicles, such as those on Trajan's Column, owe more to artistic licence than to realistic detail, so that here again methods can only be conjectured. Literary record of happenings in Britain around A.D. 120 is sparse and precise dating of events, such as Hadrian's presumed visit to Britain, rests largely on a concensus of opinion based on circumstantial evidence.

Diurnal variation of solar radiation on differently orientated surfaces of monuments

In the Northern Hemisphere and, in particular, at 6 different latitudes (38°, 42°, 45°, 48°, 50°, 56°) the flux of solar radiation which hits the vertical surfaces orientated in the eight main directions (North, North-East, East, South-East, South, South-West, West, North-West) has been computed and compared with the horizontal plane, at the time of the summer and winter solstices and equinoxes. This study has been carried out with the aim of furnishing a useful basis to calculate the quantity of energy which hits a surface, as an integral to find out when the maximum energy hits it, and to determine the time interval, during the day, during which a work of art is directly exposed to solar radiation. All this information is useful, in that solar radiation is an important forcing agent, and necessary in the biological and physico-chemical processes which lead to the degradation of a work of art. Furthermore, it is also useful for the management of the rooms or the environment around the monument, to know whether it is situated inside or outside. Therefore, the amount of energy reaching the various vertical surfaces has been compared to the amount of the energy received by the horizontal planes and which are normally acquired at the various monitoring stations. Moreover, the efficiency of the model depends on the correct choice of the atmospheric transmission coefficient α. Finally, some examples of the partial results obtained when such a model was applied to the Scrovegni Chapel, the Sistine Chapel, the Cathedral at Orvieto, the Horses of St. Mark in Venice and the Trajan Column, will be given.

Ecological approach to the genesis of calcium oxalate patinas on stone monuments

The genesis of calcium oxalate patinas on stone monuments gives rise to controversial opinions. One of the proposed hypotheses links this phenomenon to the past presence of lichens on the exposed surfaces of monuments. However, the growth of a biological species cannot occur if environmental conditions are not compatible with its autoecology. Analysis of variations of the environmental factors that can act as «limiting factors» shows that in most monuments, the various exposures are not always compatible with biological growth. The environmental factor that seems to be the most limiting is the amount of surface water that is frequently below the range of tolerance of even the most xerophylous species. In the case of Trajan's column in Rome, the distribution of oxalate layers shows an opposite trend with respect to what we would expect for lichen colonization. Presently other kinds of biological colonization cannot be excluded.

Biogenic Weathering of Marble Monuments in Didim, Turkey and in Trajan's Column, Rome

The Temple of Apollo in Didim, Turkey, was built in 560-550 B.C. with marble. Mean annual rainfall there is 656 mm. Much of the marble surface is covered by a black crust of microorganisms. Weathering patterns, associated mainly with cyanobacteria, observed there were: 1. Exfoliation with pleurocapsalean cyanobacteria in fissures. 2. Gradual removal, by splashing rain drops, of marble crystals, the coherence of which is reduced as a result of microbial activity. 3. Pits formed by cyanobacteria living in circular patches. The mechanism described in No. 2, leads there to the creation of depressions where the lithobionts are situated. Trajan's column was erected in Rome 112 C.E. Mean annual rainfall there is ca. 700 mm. The column is almost devoid of microbial life at present, but until 1942 had many patches of microbial black crusts. From 1942 to 1948 it was covered by brick walls and sand as a way of protection against war hazards. The light-demanding microorganisms that populated the monument for hundreds of years disappeared after being covered for 6 years and have not returned yet. Pits resembling those in Didim damaged much of the artistic relief on parts of Trajan's column. The most affected parts are those facing south and southeast. These are the directions of the most common incident rainfall in Rome which bring water at high energy to the marble monument.

Microclimatic factors affecting the Trajan Column

Because of meteorological and microclimatic factors (e.g. solar radiation, gradients of temperature and moisture, air speed and turbulence) the Trajan Column is subject to deposition processes on a diurnal cycle, which alternatively increase and decrease the deposition rate of airborne pollutants. The diurnal trend of the pollutant concentration in Rome is bi-modal and the two maxima are associated with different deposition velocities, so that a simple correlation between stone deterioration and pollutant concentration averages appears to be meaningless. Field tests were carried out on the monument to investigate the diurnal and seasonal trend of factors that affect dry deposition in relation to the meteorological variables and pollution levels, i.e. phoretic forces due to temperature gradients (thermophoresis), condensation and evaporation (diffusiophoresis and Stefan flow), inertial impaction, electrostatic capture and gravitational settling. In particular, when the marble is warmer than the surrounding air, a layer of warm air rises continually along the warm part of the column, increases the upward drag of the falling particles and results in a net decrease of the gravitational settling of the coarse particles (i.e. with diameter d > 1 μm); when the marble is colder, the downward drag increases the sedimentation rate. The wind field around the monument was measured in order to investigate the diffusion potential. Turbulence generated by the shape of the column and its roughness clearly dominates the natural turbulence of the free flow. Rainwater has been recognized as being the cause of severe dissolution except in zones where whewellite is present. This is seen by comparing the deterioration pattern with the rainfall rose, and by following the run-off path which is determined by the geometry of the bas-reliefs. Dissolution is due to the chemical activity of the dry and wet depositions; it is also dependent on the physical regime of the run-off, i.e. laminar or turbulent. In the past, in addition to the physico-chemical weathering, biological deterioration occurred where meteoric water remained longer. Micrometeorological field test were carried out on the Trajan Column to investigate the diurnal and seasonal evolution of the main temperature and humidity parameters to know the microclimate of the column. Four seasonal tests have been made, each of 6 days under different weather conditions. The measurements have been made on horizontal and vertical profiles at different distances from the surface to study the heat and moisture exchanges between marble and atmosphere. The wind loads and their effects on the mechanical structure resulted in being negligible.

One hundred feet and a spiral stair: the problem of designing Trajan's Column

One hundred feet and a spiral stair: the problem of designing Trajan's Column

Modelling daily thermal cycles in the Trajan Column

The propagation of the thermal wave caused by solar radiation in the first 20 cm from the surface of the Trajan Column has been analysed. There is good agreement between the model and the experimental data taken on the surface. This would lead to the simulation of the propagation of the thermal wave in the internal layers. An analysis of the sides of the column most subjected to physical stress has been made.

Reconstructing the climate and the air pollution of Rome during the life of the Trajan Column

The climate of Rome has been reconstructed on the basis of geophysical factors, documentation taken from latin literature and recent instrumental observations. The daily meteorological statistics, based on their own experience, by Roman writers, gives a clear picture of the climate when the Trajan Column was constructed. Other series that may be related to climatic events, such as the floods of the Tiber, furnish a general overview of the rainy periods in past centuries. Unbroken instrumental records of air temperature, rainfall and wind, taken at the nearby Collegio Romano provide good information on the meteorological situation over the last two centuries. Freeze-thaw cycles are not as frequent today as in the past, and reached a maximum frequency in the mid 19th century. Air pollution in Rome in the past may be considered from the size of the population, the presence of few industrial factories and the occurrence of volcanic eruptions, mainly from nearby Vesuvius, Etna, Stromboli and Vulcano. The surface of the column is covered with an oxalate patina, called ‘scialbatura’, with multiple layering. Two main hypotheses have been proposed for the natural transformation of the marble into oxalate: the biological deterioration due to lichen activity (responsible also for pitting) and chemical reaction of oxalic acid and oxalates present in the atmosphere. Past changes and fluctuations of climate and pollution have been here considered to interpret under a new light these hypotheses, and the critical number of inhabitants for making a lichen-toxic atmosphere and inhibiting the epilithic activity has been deduced. The scialbatura is less soluble (and more resistant) than the original marble; its colour is gray-pink while the Carrara marble is white. The question arises of whether the transformation of the marble into oxalate should be better considered damage (i.e. different colour and chemical composition) or a natural means of conservation. Field observation shows that deterioration of monuments can be reduced by lowering the pollutant concentration to a threshold limit; however, below this limit, lichens can live and chemical weathering (e.g. dissolution, sulphation) may be overwhelmed by biological weathering (e.g. transformation of marble in oxalate, pitting) in a rather uncontrolled way.

Trajan's Column and the Dacian Wars

Trajan's Column and the Dacian Wars

Trajan's Column: Lichens don't live here any more

The conservation of stonework exposed to the weather is a matter of growing concern worldwide. A common cause of decay is chemical pollution of the atmosphere, but investigation of deterioration in Trajan's Column, one of the world's most famous monuments, indicates that a biological factor is also involved — colonization by lichens. Paradoxically, this kind of erosion has now stopped as lichens have long ceased to grow in Rome's polluted atmosphere. It must, however, be recognised as a potential threat to marble and limestone structuring in clean areas elsewhere.

Trajan's Parthian War and the Fourth-Century Perspective

No contemporary account of Trajan's Parthian War survives, nor were any monuments set up to commemorate his exploits in the East in the same way that Trajan's Column in Rome and the trophy at Tropaeum Traiani (Adamclisi) do his Dacian Wars. We rely almost entirely on the excerpts of Dio Cassius' History preserved by Xiphilinus, together with a few fragments of Arrian's Parthica, in order to reconstruct the causes, objectives and strategy of the war. Because of the scant nature of the sources, all three aspects remain the subject of much scholarly discussion and dispute. Here, however, an attempt is made to address the problems raised by Trajan's eastern campaigns from a different perspective. References in fourth-century sources shed light not only on the purpose and execution of the war itself, but also on the way Trajan was perceived in late antiquity as a valuable paradigm for contemporary events and figures.

Propagande expression roi, image idole oracle

Paul Veyne, Propaganda Expression King, Image Idol Oracle. ? The author, a native from the group of antiquarian scholars, shows : that images are not a language, and iconology is not a whole, for what counts is the decorative ; that monarchic pomp and imagery are not propaganda but expression ; that the decor of churches has never been a bible for the illiterate ; that Greek statues are idols but three other things too ; that we hardly look at works of art, the ? ideal spectator ? being both the rule and the exception ; and that poli tical images do not symbolize power but express a self-evident legitimacy ; for there is legiti macy whenever one can manipulate it while believing that one is submitting to it, as is also done with oracles. For colleagues on antiquity, it should be added that much thought is given to the fact that the sculptures on Trajan's column were not visible ; and a stylistic interpretation is proposed of late decorations on Constantine's Arch.

La Colonne Trajane : invention, composition, disposition

Trois raisons au moins font qu'aujourd'hui il est nécessaire de repenser la colonne Trajane. La première et la plus évidente tient au douloureux problème de la conservation du monument, sur lequel les travaux entrepris par la Surintendance ont attiré l'attention générale. La seconde raison vient du fait que les échafaudages, dressés maintenant autour de la colonne à titre de protection provisoire et pour les études et les interventions de restauration et conservation, offrent une occasion unique d'observation minutieuse et directe des reliefs (dont il n'existe pas d'édition photographique complète et adéquate).

Trajan's Army on Trajan's Column.

Trajan's Army on Trajan's Column.

I. A. Richmond: Trajan's Army on Trajan's Column. Pp. x + 56; 24 plates, 2 text-figures. London: The British School at Rome, 1982. Paper, £6.50 (U.K.), £8.50 (overseas).

I. A. Richmond: Trajan's Army on Trajan's Column. Pp. x + 56; 24 plates, 2 text-figures. London: The British School at Rome, 1982. Paper, £6.50 (U.K.), £8.50 (overseas).