SEISMOLOGICAL INVESTIGATIONS 267 



has been called by Mr. J. F. Brennan, the Government Meteorologist, to 

 the remarkable character of the minor earthquakes in that island. The 

 following table, showing month by month, (a) the average number of earth- 

 quakes, and (b) the average rainfall, has been derived from his statistics. 

 The earthquake observations cover the period 1908 to 1934, the rainfall 

 records a period of 60 years. 



No. of Earthquakes. 

 Rainfall. In. 



No. of Earthquakes 

 Rainfall. In. 



It will be seen that the earthquakes are most frequent in the dry months 

 of the year. Brennan's explanation is that the shocks are due to rockfalls in 

 the underground watercourses, the geological formation of three-quarters 

 of the island being limestone. These minor earthquakes have been growing 

 less numerous in recent years as the great earthquake of 1907 has become 

 more distant. In view of an apparent association with that catastrophe 

 it is clear that closer study of the minor earthquakes is desirable. 



Work at the University Observatory, Oxford. 



Since the last report, the sections of the International Seismological Sum- 

 mary for the quarters ending 1931 September and December, also 1932 

 March, have been completed and distributed. April and May are printed, 

 and the MS. for June, July, August and September are ready for press. 

 The Summary for the whole year 1931 was sent as a bound volume to 

 recipients preferring that form to separate quarterly sections. 



A set of ' Tables for the near Earthquake Pulses,' completed by Dr. 

 Jeffreys, to supplement the Jeffreys-Bullen Tables which are the basis of 

 the Summary and are to be found in the 1930 volume, has been printed and 

 distributed as a pamphlet. 



A new list of ' Constants of Seismological Observatories ' has been pre- 

 pared and will be issued shortly. This includes 116 new stations to be 

 added to the list published by K. E. BuUen in 1933. A geographical index 

 has been added at the end. 



An Index Catalogue of Epicentres for 1913-1930, prepared by Miss E. F. 

 Bellamy, was issued in the autumn of 1936. This catalogue incorporates 

 and extends to 1930 the list published by Prof. H. H. Turner in 1920. All 

 the epicentres given in subsequent volumes of the International Seismolo- 

 gical Summary are included. The catalogue is divided into four parts, 

 the first part containing epicentres north of the equator and east of Greenwich, 

 and the other parts including the N.W., S.E. and S.W. quadrants of the 

 globe. In each part the epicentres are listed with all those in the same 

 latitude together. The total number of shocks for which epicentres were 

 determined in the 18 years was 6,738. Of these 4,007 were in the N.E. 

 quadrant, 1,106 in the N.W., 957 in the S.E. and 668 in the S.W. There 

 were 38 in the far north in latitudes as high as 70° N. but only 3 between 

 70° S. and the South Pole. The positions of the epicentres are shown on a 

 chart on the MoUweide. Equal Area Projection and the positions of seismo- 

 logical stations are shown on a similar chart. The Index Catalogue should 



