Historical Seismograms - Evidence from the AD 2000 Izu Islands ...

History of the Seismological Observatories in the British Isles 487tals in April and the Galitzin vertical in September of that year. A short periodvertical instrument, having a free period of 1.5 seconds was installed in 1938. Thisinstrument was manufactured in the observatory workshops.The observatory ceased seismological recording in 1969 and the instruments weretransferred to the Science Museum, London.9.8. OzfordThis station was set up in 1918 to take over the work done by Milne at Shide untilhis death in 1913. The International Seismological Summary was also transferredto Oxford at this time. Both organizations were under the direction of ProfessorH. H. Turner. The first instrument, a Milne-Shaw seismograph, was set up in thebasement of the Clarendon Laboratory on October 8, 1918 as an E-W component.Milne’s library was also moved to Oxford in 1919, and most of it was housed in theStudent’s Observatory.A new vault was constructed, at the University Observatory in 1927; it wasnamed the “Crombie Basement”, after 3. E. Crombie who donated the two Milne-Shaw seismographs (nos. 1 and 4) with which it was equipped. These instrumentshad free periods of 12 seconds and a damping ratio of 20:l. After some initialproblems of settlement of the 8 x 4 feet pier, the two instruments were installed inOctober 1928.The seismographs and the Milne Library were transferred from Oxford to DowneHouse, Kent, on January 22, 1947.9.9. The Coats Observatory, PaisleyA description of the observatory is given in Anderson (1901). The first seismologicalinstruments installed in the observatory were a Ewing seismoscope and aMilne seismograph. The latter instrument (no. 18) was installed in July 1898. Theoriginal building is now demolished and an extension of the Paisley Art Gallery andMuseum covers the site including the piers on which the instruments stood.In 1912 an “improved Milne”, probably a Milne-Shaw seismograph, was installed.The observatory carried out continuous seismographic recording until at least June1918.3.10. RathfarnhamA Milne-Shaw seismograph was installed at Rathfarnham Castle, Dublin, in 1919.Prior to this, Fr. W. O’Leary constructed an inverted pendulum-type of seismographin 1916 to 1917. This instrument had a mass of 1,700 kg and recorded bothN-S and E W components of ground motion. The static magnification was 300 andthe free period was 18 seconds. The theoretical description of the instrument isgiven in Ingram and Timoney (1954).In 1950 a short period vertical instrument having a free period of 1.2 seconds wasinstalled. Recording ceased at Rathfarnham in 1964.