EARTHQUAKES. (SPECIAL TO "THE PRESS.")

Press, Volume LXI, Issue 11790, 13 January 1904, Page 8

EARTHQUAKES. (SPECIAL TO "THE PRESS.")

DUNEDJN, January iM. the section of Astronomy, Mathematics, Physics, and Mechanics, the reports of the Seismological and Magnetic Committee were received. In the eeismological report no reference was made to the work done in New Zealand from January Ist, 1902, to December 31st, 1903, but a few remarks wers made by Mr G. Hogben, who has charge of the Milne seismograph at Wellington. He said that the three most important earthquakes since the last meeting of tha Association were those at Cheviot in November, 1901, in South Adelaide in September, 1902, end at Warrnambool in April, 1903. The Cheviot earthquake was very similar in character to that which threw down the Christchurch Cathedral epire in 1888, and probably came from a parallel line of fault-. One interesting fact about it was that at Wellington there was a downthrow on the western side of the station amounting to 1J seconds of arc. That would mean, if it were general over 'New Zealand, though probably it was not, a rise of 6iu on the East Coast, and a fall of Bin on the West Coast. The South Australian earthquake would, it seemed to the speaker, give a great deal of food for thought, and it Was to be hoped that the time records would be more exact in future. The system of seismic origin in South Australia and Victoria, was well worth examination. Mr Hogben concluded by moving a series of recommendations, which were adopted. One of these was that it wa.i highly desirable that Milne seismographs should be installed at Sydney, Bris bane, Hobart, Adelaide, Norfolk Island, kod, if possible, Tonga. It was necessary to complete the Australasian system il Australasia was to contribute its quota to the earthquake knowledge of the world, and it was important, to have these observations together, because one of the problems to be solved was as to the path of the earthquake waves, and until we knew the path we could not safely draw conclusions as to the elasticity and density of the rocks. Taemaniana said that there were few earthquakes there, but as a matter of fact from the beginning of 1884 to 1887 there •were 2640 earthquakes in that island, or more than in all the rest of Australasia since records began, and one of these shocks threw down chimneys 360 miles away. Within twenty-five years there had been a rise of at least SO feet at the New Hebrides. Records were wanted to enable it to be seen if there was a general rising in the floor of the Western Pacific, and that could only be found by having a large number of stations. The principal of the committee's recommendations were in the direction of installing the Milne seismographs in South Australia and Tasmania. The Magnetic Committee's report,. for warded by Mr P. Baracchi, Government Astronomer at Melbourne, stated that the only magnetic work carried on since January Ist, 1902, had been (1) the work done at the magnetio observatory in Christchurch by or under the direction of Dr. Farr; (2) the continuation of the magnetic eurvey of New Zealand by Dr. farr; and (3) the work done at the Melbourne Observatory. The programme laid put by tfie International Geographical Congress oi Berlin in 1899, in connection with Antarctic exploration, had been fully carried out, and would terminate nexjt February. Considerable progress had been made in the measurement of the soence of magnetic traces obtained at the Observatory, and extending over a period of over thirty years. The total number of day curves fully meaeured from 1868 to 1893 was about 28,000. In 1898 the Council of the Association requested the Government of Victoria to supply means to enable Mr Baracchi to initiate the work of cataloguing magnetic disturbances, and it was necessary that such subsidy be continued for a further period of two years. The report was read by Dr. Coleridge Farr and adopted. Other papers were "Earthquakes at Gknelg," by Mr H. Tarlton Phillips; 'The Universal Datum of Measure," by Mr Thos. Banker, of the Government Survey, New South Wales; "On the Construction of Scales for the Graphic Solution of Astronomical Problems," by Mr C. W. Adams (IBlenheim); "The Sifting of the Sunbeam in its Passage Through the Atmosphere io the Earth," by Mr A. H. Chapman (Oamaru); "A Comparison of the Periods of the- Electrical Vibrations Connected with Simple Circuits," <md "A Comparison of the Magnetic Declinatdon in Sydney and Melbourne," by Professor J. A. Pollock, B.Sc. (Sydney). The last paper showed that the decimation in Sydney and Melbourne followed the same course of variation, this being shown on Dr. Farr's diagrams in 1892. Mr discussed in a lengrchy paper the question whether earthquake waves are propagated along arcs or chords of the earth. His exhaustive researches, which lie detailed, had failed to determine the question.