The Ljubljanica River is a site where one of the first modern research projects of underwater archaeology in Europe took place. The rich finds of Roman bronze vessels and iron weapons found by chance in the Ljubljanica at Vrhnika, the ancient Nauportus, have led the director of the Provincial Museum in Ljubljana, Karel Dežman, to devise a large scale plan for an underwater survey of the riverbed. The plan was executed in the second half of September 1884 with the help provided by the divers from the Austro - Hungarian naval base in Pula.

Introduction

In September 1884 there was un unusual bustle to be detected on the banks of the Ljubljanica at Vrhnika, then known as Oberleibach in Carniola. It had become known that two military divers were searching the riverbed wearing unusual suits and prowling around for precious antiquities. The Ljubljanica riverbed was known as an archaeological site for some time then as numerous objects had been pulled out from the riverbed during net-fishing and regular cleaning of the riverbed with a dredge. During low water level, occuring mainly in the winter and summer months, the locals could simply pick up the objects which were easy to reach. The finds reflect the significance of the Roman Nauportus, an important military and trading post on the site of today's Vrhnika (Horvat 1990). There are some finds from the river which are of special interest, for example the numerous pieces of bronze vessels and iron weapons, but also tools, Roman amforae, and clay vessels.

With the intervention of the mayor of Vrhnika Jelovšek and other citizens, the majority of the finds was acquiered by the Provincial Museum of Carniola in Ljubljana. There they attracted the attention of the curator, Karel Dežman, a broadly educated natural scientist, archaeologist, and former deputy of state. Moreover, the location of the precious finds at Vrhnika was rendered interesting also due to the new museum building under construction at the time.

Dežman was very much interested in the site and ordered, as early as the spring of 1884, a systematic research of the entire section of the riverbed between the bridge towards Verd and the former brewery. This undertaking, despite the high financial input if compared to the previous finds by the locals, did not yield the expected results. Moreover, the finds were limited in providing information. Dežman was thereby led to seek a more efficient way of riverbed research since dredge and net research only produced large objects, with small ones missing from the assemblage altogether. Clearly well informed about the existing technology, Dežman conceived the idea of surveying the riverbed with the aid of divers, which he later successfully realized. He turned to the Austro-Hungarian Navy for the needs of this operation, since specialized military units were the only source of skilled personnel and adequate equipment and had, on many previous occasions, offered logistic support to various scientific expeditions. The request for this aid was addressed to the War Ministry in Vienna and was granted. This fact was probably aided also by the connections that Dežman had in the arsenal of the main base of the imperial and royal navy in Pula, with which he had been in contact already in the 1870s as a deputy of state.

Underwater research

A detailed research plan can be discerned from the correspondence between Dežman and the arsenal command post in Pula (Arsenalcommando) on the one side and the 2nd Group of the War Ministry's Naval Section in Vienna, responsible for technical matters (II. Geschäftsgruppe der Marinesektion des k. u. k. Kriegsministeriums) on the other.

In a letter dated August 13th, 1884, Dežman presented his project and requested an experienced diver with equipment, stressing that the museum would cover all the expenses including the compensation for destroyed or lost pieces of equipment. Work, according to his project, should commence preferably already in the autumn of the same year. The War Ministry granted his request in a matter of only a week, as Manfroni, the commander of the arsenal in Pula, gave Dežman two divers with all the necessary equipment at his disposal.

On September 17th, Davide Giraldi, a 1st class sailor, and his assistant Jože Bartonja, a 2nd class sailor, arrived by train to the station in Borovnica, then named Franzdorf. There they were met by the authorized head of research Ferdinad Schulz, a lab technician in the Museum.

Diving equipment and circumstances of underwater work

While writing the article we were hoping to discover photographs of the research taking place at Vrhnika. Local amateur photographers, however, were less likely to take an interest in the operation due to the fact that underwater reseach at the time was regarded as military secret. Taking photographs of the divers and submarines was subject to extremely strict provisions and even official military documentation officers and reporters were obliged to obtain permission from the proper authory for each picture taken.

With the direct closed-circuit system, which was the most widely used system in "civil" operations of the time, the tender on the surface supplied the air into the suit by a two-cylinder lever pump, which was operated manually. The air went from the pump through a rubber hose first into the tank on the diver’s back. The hose leading from the regulator on the tank to the helmet then ended in a mouthpiece through which the diver could inhale the air. The regulator served to control the air pressure which changed with the depth of the dive. This equipment enabled a safe dive of up to 40 metres in depth. A record breaking dive by the Austro-Hungarian Navy was carried out in 1914 in the vicinity of a small island of Porer on the west coast of Istria, where 62 metres in depth was reached (Aichelburg 1982: 35).

When air was supplied directly from the surface, the working area was limited by the length of the hose. The use of the tank, on the other hand, enabled the diver completely free movement. The Rouquayrol-Denayrouze invention also had an advantage in the case of emergency, a faulty air pump or a damaged hose that supplied the air, for example. In these cases, the diver could use the additional supply of air from the tank and safely come out of the water.

It is possible to suppose that the divers in the Ljubljanica used the diving suit only, without the tank and the regulator, unless this would have been against the rigid security regulations of the Navy. Underwater work in lower depths - in October this section of the Ljubljanica does not exceed 5 metres in depth - was relatively safe and did not require the combined autonomous diving. The diver would certainly have been more agile in the standard heavy equipment than wearing special equipment with a tank and a regulator on his back. The equipment without the tank and the regulator would have been much lighter since it weighs only 85 kilos on the surface, while with the two pieces added, the weight increases to 106 kilos. This difference is of a great importance when diving in the Ljubljanica since a diver normally had to tackle poor visibility, cool water, water current, and other obstacles such as dense vegetation, fallen tree trunks, and branches.

The equipment of the divers would also include woolen underwear, boots with lead soles weighing 10 kilos, and a signaling cord. During the work in the Ljubljanica they also used a spade and a mesh bag for finds that were lifted to the surface by a dredge. Beside the latter there was also an air pump which required the constant presence of a second member of the crew. The dredge and the pump were placed on a boat otherwise used to transport bricks from Vrhnika to Ljubljana.

Results

The research took place between September 18th and 27th in the section of the riverbed along Dolge njive. This is the precise location where the central part of Nauportus had been situated in the Early Roman period and where Dežman hoped to obtain best results. The objective of the operation was also to research the foundations of the Roman port represented by a mass of wooden piles densely driven into the riverbed along the right bank, which are still visible today.

The report, written by the divers after the research was concluded, tells us that the underwater work lasted altogether 44 hours and 15 minutes which means that they spent on average 4 and a half hours under water every day. Gathering from the agreed rate of a florin for a diver's hour, and from precise specifications on the charge for shortened dives, a single diving research would have lasted approximately 15 minutes.

After having cleaned, dried, and packed it, the equipment was ascertained to be in good condition. All pieces of equipment were later additionally checked by the commission in the arsenal in Pula. The cost of hiring the divers and the compensation for the wear and tear was determined by the Ministry. In addition to these expenses, the Museum also covered for the transport of the equipment, for food and lodging in the total sum of 156 florins and 91 kreutzers.

The operation was conducted in an exemplary manner but in spite of this, Dežman's expectations were not fulfilled. There are 33 objects on Schulz's list, with Roman and Middle Age material prevailing. Among others, there were 5 bronze vessels found, two entirely preserved iron parts of pila, an iron helmet, a sword, two spearheads, and a human skull (Dežman 1887: 42; Horvat 1990: 58).

Dežman gave recognition to both divers in a special certificate and emphasized "the exceptional usefulness of diving research for scientific purposes". This statement must, of course, be considered according to the degree of development of archaeology as a scientific discipline at the time, since the operation at Vrhnika was primarily a salvage operation whose aim was to acquire new exhibits. The absence of any kind of documentation as regards the position of the finds shows that the divers merely researched the riverbed without in any way documenting spatial relationships among the finds and their contexts, and the role of the lab technician Schulz was limited solely on producing the inventory of the objects. Nevertheless, Dežman's decision for employing this sort of riverbed researched could be judged as very advanced for his time since it is probably one of the first cases of the helmet-diving system being employed for research rather than commercial purposes. The operation at Vrhnika can therefore be considered as one of the early achievements of underwater archaeology. It stands alongside feats such as the lift of artefacts from the Antikythera wreck in 1900 and the research of the Chiché n Itzá sacred well (Cenote) in 1909. In connection with this we should also mention the reconnaissance of the site of Roman sarcophagi on the seabed near Vranjic not far from the ancient Salona in Dalmatia, an operation practically unknown to the professional public. The reconnaissance was ordered by the director of the Archaeological Museum in Split Frane Bulić in 1898 and executed by the divers of the Governo Centrale Marittimo from Trieste (Bulić 1899).

Conclusion

At the time when the diving research at Vrhnika took place, the Provincial Museum already held numerous finds from the riverbed at Ljubljana, acquired during the regulation work on the river in the city centre between the years 1821 and 1877. Not many people could imagine, however, what a treasure-trove the riverbed in its 19 km stretch across the Ljubljanica Moor would turn out to be. According to analyses conducted so far, the site yielded over 15,000 pieces of cultural heritage up to the present moment spanning from the Neolithic to the Late Middle Age (Bitenc, Knific 1997). The site remained untouched all until the 1970s when amateurs with SCUBA gear began to search the riverbed. From 1980 onwards, organized professional interventions are taking place, lately in the form of systematic research conducted by the Group for Underwater Archaeology.

Acknowledgements

We would like to thank Sergio Gobbo, who provided us with the photo of the military divers from Pula. The correspondence between Dežman and the War Ministry that has been used in writing the article is kept in the War Archive of the Austrian State Archives and in the National Museum of Slovenia.

Bibliography

Aichelburg, W., 1982, K.u.K. Dampfschiffe: Kriegs, Handels und Passagierschiffe in alten Photographien. Wien.

Bitenc, P., Knific, T. 1997, The Ljubljanica as an archaeological site (Summary), Argo 40/2, 19-32. Ljubljana.

Bulić, F., 1899, Tre sarcofaghi romani nel villaggio di Vranjic (Urania) sotto il livello del mare, Bullettino di archeologia e storia dalmata 22, 105-111.

Dežman, K., 1887, Ueber Funde von gallischen Mü nzen und anderer Gegenstä nde bei Ober-Laibach, Mittheilungen der k. k. Central-Commission zur Erforschung und Erhaltung der Kunst- und historischen Denkmale 13, 142-145. Wien.

Horvat, J., 1990, Nauportus (Vrhnika), Dela 1. razreda SAZU 33. Ljubljana.

Many thanks to Andrej Gaspari and Žarko Sajic for their fantastic help with this article!

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• this page was last edited on February 12th 2006