Technikatörténeti szemle 13. (1982)

TANULMÁNYOK - Fejér László: Fejezetek a folyami vízsebességmérés történetéből

turns of the paddle wheels driven by the water were counted by a gear engaged to it. This equipment enables engineers of the 19th century to carry out measurements of water velocity indispensable to the completion of river regulation plans. Really serious hydrometric works was started in Hungary in 1820 with the mapping of the Danube. The head of these works — Mátyás Huszár — tried to solve the problems of water velocity measurements as well. He improved the equipments used at that time by several ideas. His successor Pál Vásárhelyi determined in 1838 in the Budapest section of the Danube water discharge by spot measurements of which there was no precedent at that time. On the basis of his measurements he has first came to the conclusion that the distribution of velocity ratio measured vertically in the channel gives a parabola. One of the first graphic representations of the discharge curve can be found in his study published in 1845. The original equipment of Woltman went through several alterations in the second half of the last century. The most decisive change was to find solution for electric tachometry. The equipment designed by Rudolph Harlacher made superfluous rising the instrument from water after each measurement and promoted the horisontal and vertical integral measurements used by Gyula Revy and Georg Treviranus. Reknown Hungarian pioneers helped the development of the equipment as well. The measurement of Ignác Horváth, professor of the Pest Technical University, on the Danube in 1876 were carried out with caution and accuracy surpassing such work before. Revolutions of the wing were registered by a Morse-system typewriter on a paper strip. At the same time the velocity of the wind and the scabridity of the bed were measured as well. In his study published in 1877 Jenő Kvassay analysed the relation between the revolution number of the wing and the velocity, gave the mathematical relation of sizing the wing paddles. Samuel Hajos used for his équipement helix formed paddles with pointed ends wich were imediately attached to the shaft of the current meter. This equipment was introduced by the Hungarian hydrographic service in 1892 and had been used with larger or smaller alterations for half a century.