Petercsák Tivadar – Váradi Adél szerk.: A népvándorláskor kutatóinak kilencedik konferenciája : Eger, 1998. szeptember 18-20. / Heves megyei régészeti közlemények 2. (Eger, 2000)

Finger-Print of the Fisherman's Hut

416 SZENTGYÖRGYI VIKTOR - MEZEI ISTVÁN - BÚZÁS MIKLÓS FINGER-PRINT OF THE FISHERMAN'S HUT Viktor Szentgyörgyi - István Mezei - Miklós Búzás Between 1996 and 1999 two houses were reconstructed írom the Árpádian period (Figs 1-2) in the experimental archaeological settlement at Ópusztaszer, which bears János Ormándy the founder's name, who died young. The second building, the „sunken dwelling house" from Kardoskút (Fig. 2) was covered with a sod roof with regard to István Méri archaeologist's observations. Two rafters broke in the small hut covered with a sod roof during the winter following its construction. We understood only later that some accidentally made observations in consequence of the unlucky(?) event led to solving of a problem that archaeology had thought insoluble. The problem is that the roofs of these early building were built of purely perishable materials most probably without applying conservation techniques. The overground parts of the buildings, including the entire roof, perished practically without trace and thus cannot be the object of an archaeological study. The real measurements of the houses cannot be told from the phenomena observed by archaeological excavations. Up to now we could not find any phenomenon that would certainly prove to what distance from the edge of the dwelling pit the rafters leaned to the ground. We cannot tell what size was the surface the totally perished roof covered outside the dwelling pit. We similarly do not know the height of the roof, its angle, the length of the rafters, the type of the timber-work etc. We had to admit that the one-time roofs covering the sunken dwelling houses will forever stay unknown... The replacement of the rafters in the dwelling house of the Árpádian period covered with sod roof could be solved with contemporary equipment only in a single way. This method necessitated the creation of a ditch, a „peduncle" starting from the earthen wall of the pit of then house. The experiments were followed by archaeological data collection: we found the characteristic ditches attached to the pits of the houses in the medieval archaeological legacy. The experiments leading to the solving of the function of the „peduncles" and the archaeological observations regarding the „peduncled dwelling pits" are published separately in a paper titled „The „peduncle" of Árpádian period houses". Two very important conclusions can be drawn from the function of the characteristic canallike ditches attached to the earthen wall of the dwelling pit as its organic element. The first is that the „peduncle" in itself proves the presence of a platform, an area outside the dwelling pit but under the roof, since it bridges it. The other one is that the „peduncle" clearly indicates the size (projection) of the platform above it in the plane of the rafter built in with its help: it ends right under the roof, that is the lower end of the rafter in its ultimate position is placed in the rounded terminal of the ditch. A third conclusion can also be drawn in knowledge of the function of the characteristic ditches beside the above two consequences, which are valuable in themselves: the „peduncles" bear information also about elements of the perishing elements of the house! Starting from the remained traces traces, the „peduncles", the totally perished trussing of the several thousand years old roof can exactly be reconstructed in accurate dimensions using mathematical methods. If no serious damage is caused to the „peduncled dwelling pit" as an archaeological find, at least six measurements can be calculated with a mathematical model concerning the measurements of the roof above it: the height of the purlin from the contemporary floor level, the interior height of the building, the length and lower diameter of the rafter built in with the help of the „peduncle", the angle between the roof and the contemporary exterior floor level above the „peduncle", and the size (projection) of the area outside the dwelling pit and under the roof (platform) under the rafter built in with the help of the „peduncle". The purpose of the present study is to describe the ideas and the mathematical model that connect the phenomena observed at excavations with the perished roof and to explain them to the readers who are not used to a mathematical train of thought. As it is common, the argumentation started with the establishment of a zero hypothesis (step 1). In our case the zero hypothesis states that the ,,peduncle"of the Árpádian period houses was used for the replacement of the rafters in the way we ourselves made it. The zero hypothesis cannot be either rejected or accepted without a good reason so some of the examinations were carried out to prove it. It is a very interesting question how such a complex zero hypothesis can be proved with mathematical methods. The related arguments (step 6) are based on the „principle of small targets". Using the characteristic geometric consequences of the validity of the zero hypothesis, the different measurements of the entirely perished roof can exactly be calculated. First of all the „peduncled dwelling pits" had to be classified from the respect of the mathematical elaboration (step 2.). Inevitably eight groups were separated by the classification (A-H), the differentiation of which was certainly justified. Although these eight groups must certainly be differentiated from the point of view of the mathematical analysis at the calculation of the measurements of the roof and during all the following steps of the mathematical argumentation, an identical logic was used in all eight groups. So the chain of thought that led to the reconstruction of the perished roof is sufficient to be demonstrated in one of the groups. The detailed mathematical argumentation will be