Deák Antal András: A Duna fölfedezése

Tartalom - III.A DANUBIUS PANNONICO-MYSICUS, 1726

T II E DISCOVERY OF THE DANUBE did not show the actual place of the weight at the end of the cord. A reliable velocimeter was constructed only about 200 years later. Nevertheless, he conscientiously measured the speed of the water close to the surface, near the bottom of the riverbed and in the middle. He made such measurements at the Pétervárad bridge on the Danube, at Zsablya on the Tisza and at the bridge near Becse also on the Tisza. He tried to discover the connection between depth and speed from these measurement data. From the data measured at Pétervárad he concluded that the speed of the water was nearly three times faster near the bottom than on the surface (the quadrant displayed a value of 12 degrees on average on the surface, 26 degrees in the middle and 30 degrees near the bottom). He listed the measurement data in three charts. Marsigli also investigated the waters in the collection area of the Danube-, flowing waters, stagnant waters, the water in wells, mineral waters, waters coming from hail and rain and the water from thermal springs. He analysed their composition and arranged the data in 5 charts the size of a double folio, in which he also indicated the places where the analyses were made. In the following pages, he summed up and evaluated the results. He deduced that the water of the Tisza was the worst among the rivers he examined (he made the observations on the north bank at Szeged). As he said, it smelled very much of earth when he examined it in October, and found that it had a bad tang of swamp, its colour was dark and contained much silt and many insects. He judged the water of the Maros the best, which he examined on the 4

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h of October near Makó: it was clear, odourless and tasted very good. He evaluated the waters of the tributaries of the Danube and the waters described above from the collection area of the Danube using the same method. He collected information on the indigenous plants of the Danube region in a chart with four columns. The plants were named and classified according to the História Tabernamontana reformata a German language catalogue (the details were not given) in the first column and following Gasparus Bauhin in the second column. The provenance of the plants (on roadsides, hillsides, sandy slopes etc) was indicated in the third column, while the fourth column contained their actual occurrence (at Buda and at the mouth of the Drava, in the environs of Esztergom, at Baja etc.). He did not omit quadrupeds from the description of the fauna along the Danube, although he dealt in detail only with red deer antler. He made series of measurements with barometers and thermometers during an inquiry against him

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4 in Vienna between the 11

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h of December 1696 and the 30

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h of August 1697. In the short introduction to the chapter, which he probably wrote just before the manuscript went to press, he himself emphasised the pioneering quality of his work. Namely, he did not know of anybody who had made similar thematic measurements either on the seashore or in the middle of a continent. He believed that similar observations were regularly pursued in Europe only thirty years later on the initiatives of the English Royal Society.

295 He worked with two barometers and four thermometers. When necessary, he also used a microscope for the analysis of snow crystals, as he himself had used it for studying minerals and insects. A wind vane showed the direction of the wind and registered values to the exactitude of secondary cardinal points. He could not measure the force of the wind but he found it important to register relative strength: gently blowing, strongly blowing, no wind, the air is pleasant and calm... 29

4 He was accused ofmisdirecting funds but was acquitted of the charge. 2 1

5 Lajos Bartha: The first experimental Central European meteorological station was established 300 years giving a writen overview of Marsigli's meteorological work. He believes that Marsigli used a methodology followed by some English scientist such as Boyle, Halley, Hooke or Newton (Légkör, 42. évf. 3. sz. 1997). IMAGE No. 45 on page 82; The results of water speed measurements on the Danube and the Tisza IMAGE No. 46 on page 83:The table illustrates the changes of air quality in the winter 1696/97 154