Sir Alfred Ewing and Seismometry

Abstract

DR. C. DAVISON writes: “During the five years (1878-83) that Ewing spent in Japan, like other English teachers in Tokyo he was infected by the enthusiasm of Prof. John Milne, and became one of the first members, and afterwards a vice-president, of the Seismological Society of Japan founded by Milne in 1880. At one of the early meetings of the Society in that year, Ewing described his seismograph for horizontal motion, in which he preceded Rebeur-Paschwitz in devising a horizontal pendulum with two fixed supports. In 1881, he followed with an account of a seismometer for vertical motion, this, with the preceding, forming the well-known instrument made by the Cambridge Instrument Co., Ltd. In the following year, he devised his duplex pendulum seismometer. The horizontal pendulum was erected in the Engineering Laboratory of the University of Tokyo in November 1880, and, at several later meetings of the Seismological Society, he exhibited the diagrams obtained with it. The interest aroused by these early accurate records of the movements of the ground during an earthquake can be readily imagined. Shortly before he left Japan, Ewing wrote his great memoir on ‘Earthquake Measurement’, in which he described the various forms of known seismographs and their underlying principles (Tokyo Univ. Sci. Dept. Mems., No. 9; 1883). Soon after this, his active interest in seismometry seems to have ceased, for, after his return to Great Britain, he made only one new contribution, that on seismometric measurements of the vibrations of the Tay Bridge during the passing of railway trains (Roy. Soc. Proc., 44, 394-402; 1888). In these experiments made with a duplex pendulum seismometer, he showed that the greatest lateral and longitudinal movements of the bridge were about iv in. and A in. respectively.”