Fejér László – Lászlóffy Woldemár: A hidrometria magyarországi fejlődése (1700-1945) (Vízügyi Történeti Füzetek 13. Budapest, 1986)

Idegen nyelvű összefoglalók

23. A page from the log of float measurements at Szeged. 24. Drawing of an Amsler-Laffon-made Woltman-type current meter from Ignác HORVÁTH's manuscript. In the majority of cases Ignác HORVÁTH himself used this type of instrument for his measurements on the Danube. 25. Drawing of an instrument lowering device designed by János CSONKA for the Tokaj river agency. József PÉCH, the organizátor and, until his death, leader of the Hydrographie Section. 26. Floating bridge of the Hydrographie Section. F = horizontal beam; T = lowering machine; R = closing device for the cable spanned over the crosssection; S = Hajós-type current meter. 27. Floating member for flow velocity measurements. 28. Example on the processing of results given by a flow velocity measurement. 29. Example on the comprehensive representation of discharge measurement results, on the basis of measurements at Szentes in 1887/1888. The numbers beside the line with inscription ,,mass discharge" indicate the direction and magnitude of changes in water stage during measurement, in mm/h. The line indicating the magnitude of crosssection area and mean velocity is an integral part of the presentation. Sámuel HAJOS, engineer, prominent designer of instruments. 30. Hajós-type current meter in its original case, with two vanes of different pitch. 31. Water cone formed before vanes, cut by a plan perpendicular to the direction of flow. 32. Current meter designed by the American HASKELL. 33. Fluctuation of flow velocity at different depths in the Szentes cross-section of the Tisza river, as found by the measurements performed on the 31 st August, 1887. Similar observations had been made by HARLACHER in his measurements performed in 1877 on the Elbe river at Tetschen (Decin). 34. Writing machine used initially for detailed measurements. A = driving wheel which follows the movement of the winch serving the lovering of the meter, transmitted by chain; C = cylinders for passing the tapes on; L = lever for passing the tape on during both lowering (position ij

, connection r

1

— r

4 ) and raising (position i

2 , connection r

l — r

3 — r

4 ) of the instrument. 35. Comparison of flow velocity measurements executed by different methods, on the basis of mean velocity curves. Results obtained in a detailed measurement during raising of the instrument are shown by the mean velocity curve composed of points, while the same at lowering is shown in thin solid line. The result of a point measurement is shown by the curve drawn in thick solid line. Results obtained in an integrating measurement during the raising of the instrument are shown in thin dotted line, while the curve of mean velocities obtained by an integrating measurement with a lowered instrument is shown in thick dotted line. 36. Precise gauge used by the Hydrographie Section for study measurements. The undulation of water surface is attenuated by a floating member; water could enter the tube driven down to the bed only through a tiny hole. Reading accuracy is 0.5 mm. 37. Course of water stages, surface slope and water level variation during study measurements performed in March 1898 at Tiszapüspöki. 38. Discharge rating curve given by the Tiszapüspöki measurements. The start of measurement is marked by an arrow; up to water stage 8.10 m permanently increasing discharges are obtained but here the discharges start to decrease, despite further rises in the water stage. Further decrease of discharges goes parallel to the drop of water stages. Discharges pertaining to the same water stage as measured during rise and drop, respectively, can be characterized by the fact, e.g., that at water stage 7.05 m their difference was —940 m

3

/s that is ~37%.