Deák Antal András: A Duna fölfedezése

Tartalom - III.A DANUBIUS PANNONICO-MYSICUS, 1726

T II E DISCOVERY OF THE DANUBE relative altitudes of the mountains, valleys and rivers crossed by the lines: the Danube, the Olt, the Maros, the Szamos, the Tisza, the Boszna, the Drina, the Sava, the Temes, the Verbas, the Drava, the Ipoly, the Garam and the Vág rivers are illustrated in the four section drawings. The altitudes were measured with a barometer. Seventy years later, Miksa Hell and János Sajnovics measured the altitudes of the places using the same method on their journey to the island of Vardö to observe Venus as it passed in front of the Sun.

277 After having drawn the picture of the watershed area, Marsigli described one by one the rivers running into the Danube, naming their source region, their mouth and length and classified them into groups II, III and IV depending on their size. Then, he returned to the Danube and examined the structure and composition of its bed and its banks. Then cross-sections followed to provide a visual aid to the values hidden within the numbers. He then measured the width and the depth of the Danube river in 8 places, of the Sava in 2 places, at one place on the Tisza and also at a single place on the Maros river. He made the same measurements at Vienna, Pest and Komárom as well, but these cross-sections have been lost, he added, excusing himself. He published an interesting cross-section here, which depicts the Danube (at Dömsöd) on one side and the Tisza (at Szeged) on the other and the two areas spanned by the Danube-Tisza interfluve with an indication of soil quality.

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8 This picture reveals Marsigli's interest in the connection between rivers and swamps and rivers and lakes, and the underground connections between individual bodies of waters. According to popular belief, he said, both Lake Fertő and the Balaton were fed by the Danube. In another place: There is a whirlpool beneath Komárom, he wrote, near the village of Almás, from which people say the Balaton originates, lying as it does between the hills on this side of the Drava in Hungary. He was convinced about the existence of some kind of an underground connection between bodies of waters, even if not in this form. He noted a phenomenon in the Danube-Tisza interfluve that had not yet been explored although experts corroborated its existence. He described it in the chapter The underground connection between the swamps of the Danube and the Tisza. He probably intended to place the above-mentioned crosssection of the Danube-Tisza interfluve in this chapter. We also examined that part of the territory, he wrote, which isen closed by the lower reaches of the Danube and the Tisza at Backa and I supposed that there existed ramifying underground water courses that connected the swamps of the Danube and the Tisza. I deduced it from the supposition that the two rivers ran parallel to each other, that is, both have the same course, while the tilt of the Plain is slight. He observed a demonstration of this theory. In the summer of 1693, the water in the Tisza rose very high and the flood was long lasting. The water retreated very slowly because of the great bends (at that time the Tisza meandered along a path 453 km longer than at present) and the wide swamps. At the same time, Marsigli recounted, there was barely any water in the Danube and its swamps. Yet, the lowlying fields of the Danube-Tisza interfluve lay beneath water and the seepage of groundwater flooded the crops in the flood plain of the Danube at Backa. This meant that the water flowed from the east to the west in the Danube-Tisza interfluve, that is, from the direction of the Tisza towards the Danube. Specialists now think that underground water flows through the loose alluvial soil influencing the development of groundwater in the plains which seems to support Marsigli's observations and the hypothesis built on them. In the summer of 2000, when groundwater caused particularly many problems, water surfaced in places where its appearance would not normally be expected. In this respect, there is an increasingly accepted theory that there 27

7 Sajnovics's diary 1768-1769-1770. (translated by András Deák) Budapest, 1990. 27

8 DPM Tom. I. p. 75. 144