著者

高橋 幸紀 杉山 滋郎

出版者

日本科学史学会

雑誌

科学史研究 (ISSN:21887535)

巻号頁・発行日

vol.43, no.231, pp.138-149, 2004 (Released:2021-08-12)

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This paper deals with a string of gravity measurements conducted by TANAKADATE Aikitu(1856-1952), one of the first graduates from the College of Science, University of Tokyo. These measurements were conducted with no substantial help from the Western scholars in the 1880s, when approximately only a decade had elapsed since the beginning of full introduction of Western sciences into Japan, and only a couple of years had passed since Tanakadate's graduation from the college. The aim of the measurements, the hypothesis considered prior to each measurement, and the manner of dealing with the data acquired are clarified to the maximum possible extent by careful examination of the existing documents. Some common features are found in their studies when compared with those conducted by the Western researchers at the same period. Tanakadate and other Japanese scientists, who worked with him, aimed at confirming their hypothesis that the gravity anomaly around the Japan islands should be positive. The gravity anomaly at Bonin island, in particular, was known to be the largest in the world and a geodesic or geophysical explanation for this was expected. When Tanakadate became aware of the anomaly, he considered that it could be caused by 'some failure in measurements', which led him to attempt a second measurement of the gravity at the same point. On the other hand, scholars in Europe had already acknowledged that gravity anomalies on isolated islands were generally larger than those observed on the continents and along the coasts, and no longer raised any doubt regarding the reliability of the data provided on isolated islands. They subsequently tried to determine the geophysical cause of the large anomalies and attempted to invent a suitable method for reducing the data, while Tanakadate and other Japanese researchers never applied the necessary reduction techniques to the data they had obtained.