Journal of the Geodetic Society of Japan
Online ISSN : 2185-517X
Print ISSN : 0038-0830
ISSN-L : 0038-0830
Volume 5, Issue 2
Displaying 1-4 of 4 articles from this issue
  • Sigetugu TAKAGI, Genkichi MURAKAMI
    1959 Volume 5 Issue 2 Pages 37-41
    Published: February 28, 1959
    Released on J-STAGE: July 05, 2011
    JOURNAL FREE ACCESS
    The redetermination of the longitude of Mizusawa was pursued at Mizusawa Observatory since 1953 till 1955 for the purpose of the investigation of the longitude variation at Mizusawa. The final results are;
    9h24m31s.411 E
    For convenience the following value of the longitude is adopted as the official one;
    9e24m31s. 400 E
    In comparison with the former determination in 1902, it can be seen that there was no displacement of Mizusawa since 1902 till now, which is the negative answer to the discussion about the existence of the eastward flow of the Japan Island . Whereas recent results of time observations with PZT show us the apparent westward drift of Mizusawa longitude amounting about 8 ms a year.
    Download PDF (717K)
  • Tetsuro HAYASHI
    1959 Volume 5 Issue 2 Pages 42-48
    Published: February 28, 1959
    Released on J-STAGE: September 07, 2010
    JOURNAL FREE ACCESS
    In order to investigate the state of the seiche, a simultaneous observation of the secon dary undulation was carried out at six stations around and near Aburatsubo Bay, for the period from Feb. 11 to Mar. 27, 1958. In addition, atmospheric pressure and wind in the area were incessantly recorded throughout above mentioned period. The following conclusions were obtained by the investigations. (1) The observed periods of the seiche for both branched bays, Moroiso and Aburatsubo, are 13.515.5 min much the same for both bays, while their theoretical values are 12.8 min and 14.0 min respectively. The variation of the period seems to be due to the unsteadiness of the nodal line. (2) In winter, the seiche most frequently rises immediately after W- or WSW-wind that blows for 1020 hours, 58 (Beaufort) in force suddenly changes its direction or dec reases its force in short time. In view of above phenomenon, when the water at the end of the bay that was risen by the W- or WSW-wind-the upheaval amount of the sea level is about 12 mm per m/secin WSW-wind-returns to the normal state for sudden change of the wind, perhaps the moving of the water resonates to the proper period of the bay, then the seiche will be enforced.
    Download PDF (893K)
  • Yoko MIKUMO
    1959 Volume 5 Issue 2 Pages 49-52
    Published: February 28, 1959
    Released on J-STAGE: July 05, 2011
    JOURNAL FREE ACCESS
    In order to select the most suitable method of harmonic analysis for tidal variation of gravity, and to check the methodical difference in the tidal factor-G, the three methods of analysis, the Darwin's, Doodson's and Lecolazet's, were applied to the data obtained with the Askania gravimeter at two stations, Kyoto and Matsushiro.
    Comparing the results in three cases with each other, the obtained values of G show the maximum difference of 10 percent. From the present treatment, it is provisionally concluded that the Doodson's method is preferable in case of monotonous drift and the Lecolazet's is suitable for the case of irregular drift.
    Download PDF (534K)
  • Yoshimichi HARADA, Hiromiti SUZUKI, Shin-ichi OHASHI
    1959 Volume 5 Issue 2 Pages 53-60
    Published: February 28, 1959
    Released on J-STAGE: September 07, 2010
    JOURNAL FREE ACCESS
    Gravity values at Singapore, University of Malaya, and Cape Town, Trigonometrical Survey Office, were determined relative to Chiba, Geographical Survey Institute, by means of a G.S.I, pendulum apparatus. This work was an item of scientific observations carried out by the Second Japanese Antarctic Research Expedition in 1957-8. The differences in gravity values have been found to be as follows;g Singapore -g Chiba= -1709.3±0.45 milligal, g Cape Town -g Chiba = -142.8±0.45 milligal. In Singapore, a new gravity station for our pendulum observation was established at Geography Department, University of Malaya. Other gravity stations which have hitherto been established in Singapore, Raffles Museum, Kallang airport, etc. were re-occupied with a Worden gravimeter. The gravity value at the pendulum station was found to be 0.6 milligal greater than that at Raffles Museum and to be 0.1 milligal smaller than that at Kallang airport. The pendulum station of Cape Town is same as that occupied by A.L. HALES and D.I. GOUGH with a Cambridge pendulum apparatus for their measurement of gravity in South Africa in 1948 and also by W.E. BoNINI and G.P. WOOLLARD with a Gulf pendulum apparatus and two Worden gravimeters for their world gravity measurement. The difference in gravity values at Cape Town and Washington D.C., Coast and Geodetic Survey, g Cape Town -- .g Washington, which is calculated from results of two gravity ties, Cape TownTeddington tie and Teddington -Ottawa - Washington tie both with the Cambridge pendulum apparatus, is -471.8 milligals or -471.0 milligals; the former is original and the latter is adjusted value. On the other hand, another value of this difference obtained by combining the result of present tie with that of Washington -Chiba tie both by means of the G.S.I. pendulum apparatus is -472.6 milligals. A closure of 0.8 or 1.6 milligal has been yielded from the two values above mentioned. Unfortunately, we could not land "Syowa base", a Japanese Antarctic station, in our expedition. Gravity measurement, however, were carried out with the Worden gravimeter at nine stations on very closed pack-ice in Lutzow-Holm bay. Since observation was made on pack-ice, even though its thickness was over five meters, there was always observed a slight vertical movement. The effect of the movement on gravity value can be estimated to be ten milligals or less. The gravimeter used had stable and small drift which was comfirmed by continuous reading at Singapore and Cape Town. The drift rate adopted was + 0.20 milligal per day which was deduced from the closure at Cape Town after 88.1 days' voyage in Antarctica. Therefore, probable error due to inadequacy of the drift rate of the gravimeter also being taken into consideration, it is estimated that final accuracy of the measurement in this region might be ten milligals. The gravity value at all stations in Lutzow-Holm bay determined refering to Cape Town are larger than the normal value given be the international gravity formula, the magnitude of positive anomaly amounting to about +50 milligals in average . This amount of positive anomaly far exceeds the value of the estimated error in observation.
    Download PDF (936K)
feedback
Top