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Wall Heating Systems in the Roman Period Lycian Baths - The Examples from Patara and Tlos-
F. Fatih GÜLŞEN*
The scope of the present study is to explore in detail the applied to the wall heating systems of Lycian bathhouses and to identify the inter-regional relations through their architectural features based on new evidence from surface remains and excavation results obtained from the bathhouses in Patara and Tlos.

The employment of wall heating systems in bathhouses aimed at optimising the use of heat produced by carrying it to the walls, thus increasing the temperature in the baths. Wall heating systems first used tegulae hamatae / tegula-mammatae. This technique employed large square terracotta plaques with small feet in the corners through which metal pins could pass (tegulae mammatae). The plaques were mounted on the wall surface using T-shaped clamps, pins or rarely terracotta pins. The hot air from the hypocaust was thus circulated in the gap between the wall and these plaques.

Another one of the most important and common material used for wall heating systems is the tubuli. Perforated bricks (water pipes) were generally called tubuli in ancient literature. There are various types of perforated bricks. Tubuli were the most common technique employed in Roman Imperial period bathhouses. However in Lycia, the most common wall heating system element used are terracotta pins. Although most have not been excavated yet, holes for terracotta nails have been attested in 14 bathhouses in 10 Lycian towns to date; however, it should be noted that not all the Lycian bathhouses have the wall heating system.

There exists no fixed Roman dimension for the plaques covering the wall heating system elements; however, in Lycia, they can be square or rectangular in shape, sometimes with a ratio of 1:2, 2:3 or 4:5 between their widths and lengths; they can be placed horizontally or vertically.

In the caldarium and tepidarium of the Palaestra Baths in Tlos are holes for terracotta pins in the arched or flat niches. Each niche is connected to the hypocaust individually forming a panel; this is a unique feature of the Palaestra Baths of Tlos in Lycia. It is possible to see the traces of the terracotta plaques covering over the terracotta nails in all the niches and the surviving terracotta pipes in the chimneys.

The chimneys of the in-wall heating systems are seen above the projecting cornices of numerous Lycian bathhouses such as at the Nero-Vespasian, Hurmalık and Small Baths in Patara, at the Palaestra and Large Baths in Tlos, at the Antoninus Pius Baths in Kyaneai and at the Limyra Baths. The bottom sides of the projecting cornices of the Nero-Vespasian, Hurmalık and Small Baths at Patara are carved in a concave form, forming a semicircular route to facilitate the movement of the hot air to the chimneys. The cornices of the Large Baths in Tlos project, but their bottom sides are flat, while those of the Palaestra Baths are flat at the bottom and are angled at the top. The cornices originally bearing the weight of the vaulted superstructure became an outlet suitable for the chimney sockets of the wall heating systems.

At the Stabian Baths in Pompeii, tegulae mammatae are found in the caldarium while tubuli are found in the tepidarium. However, no example is known to date where the tubuli and terracotta pin methods were employed together. Vertical recesses in the walls functioning as chimney canals have been attested at the Large Baths in Tlos, Nero-Vespasian, Hurmalık and Central Baths at Patara as well as at the MI 1 baths at Oinoanda, and the Sidyma and Nisa Baths. On the other hand, round chimney holes have been attested at the Small Baths at Patara. Apart from the Nisa example, the terracotta pins and chimney canals were employed together in the same rooms. However, it is not known whether these were in use at the same time or during different periods, that can only be clarified after excavations. At the Palaestra Baths at Tlos only terracotta pins were used while at the Large Baths probably there was no wall heating system employed, or if used, then it should have been tubuli. In case tubuli is attested at the Large Baths in Tlos, then this will be the only known example in Lycia.

Although for the time being, there is no known example where the tegulae mammatae and terracota pins were employed together, taking into consideration the parallels between them it will not be surprising in the future to discover Lycian baths employing both elements together. Thus, the transition from the tegulae mammatae – the earliest wall heating system element widely used in central and provincial Roman Imperials baths – to the terracotta pins – Lycia’s peculiar wall heating system element – will be clarified with regard to where, how and when as well as its stages of employment.

Despite the differing advantages of wall heating system elements, in Lycia, the terracotta pin system must have been preferred due to factors such as: traditions, climate, durability, cost, technical availabilities, practices, maintenance, the employment of local masters, with the heating productivity in a bathhouse not exceeding a surface area of 1,000 sqm.; thus, it found widespread practice in Lycia and entire Mediterranean basin outside central Rome.

In Central Rome, there is not one bathhouse that is known to have employed terracotta pin system, this system is commonly found, outside Italy, in Pergamum, Kourion (Cyprus), Knossos, Maktaris (Tunisia), Gortyn, Cherchel, Tehouda, Timgad as well as in northwest Europe and the Levant (Palestine and Syria) during the Roman Imperial period. Among the Roman Imperial provinces in Anatolia, except Lycia, although there are examples known from outside Lycia, tubuli were used more widely than the terracotta pins. For example, although the Pamphylian bathhouses were influenced by the Lycian examples regarding their overall design and planning, curiously enough, tubuli were preferred in Pamphylia instead of the terracotta pins.

It is not known exactly when and where the terracotta pin technique first emerged, but the terracotta pins are thought to have been a primitive type of tegulae mammata. In spite of the similarities between these two systems, the structure of the plaques and mounting techniques employed are different. It does not seem plausible that Rome exported the terracotta pin technique, which it did not use in its centre, out to Lycia and other provinces. The sites where this terracotta pin system is attested have different types, profiles and fitting holes for the terracotta pins from those employed in Lycia. In addition, in the Roman Imperial period, the baths with a terracotta pin system are mostly dated to the 2nd century A.D., some are even from the late 2nd – early 3rd centuries. On the other hand, the earliest bathhouse in Lycia is the Nero-Vespasian Baths in Patara – named as the Vespasian Baths until recently when it was understood to have been built in the reign of Nero together with the water supply system – which date earlier than the abovementioned examples employing this system. Although there is no known example of Lycian baths dating earlier than the reign of Nero, it will not be surprising to expect baths dating earlier at Patara with its special geographic location and political position with the fact of being a port city. In the light of this evidence, the supposition that there existed no baths predating the Flavians period is no longer valid. The Vespasian Baths in Kadyanda and the Kandyba Baths can also be cited among the earliest baths of Lycia; the baths employing this system in other regions are all dated much later than the Lycian examples. Thus, it would not be a mistake to claim that this wall heating element was peculiar to Lycia, the terracotta pin technique established as a model, with its early date, for the other examples observed in Anatolia and in the other provinces of the Empire.

With the emergence of this wall heating technique, the architecture and heating systems of the baths improved greatly and it became easier to cover wide spans with windows and to warm up the large caldaria and tepidaria. Consequently, the layouts of the baths were also influenced and new bathhouse plans with apses and wide panoramic windows appeared, creating decorative and articulated bathhouse façades. Heat and damp could be easily regulated with advancements made in tegulae mammatae, tubuli and terracotta nail techniques, and thus the hot and dry air provided the bathers with comfort in Roman Imperial period baths.

*F. Fatih Gülşen
Akdeniz Üniversitesi, Fen-Edebiyat Fakültesi, Arkeoloji Bölümü, Likya Araştırma Merkezi, Kampüs 07040 Antalya.
E-mail: fgulsen@akdeniz.edu.tr

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