266 REPORTS ON THE STATE OF SCIENCE, ETC. 



The Belgian Earthquake of June ii, 1938. 



During the 12-month period the most important earthquakes originating 

 beneath the British Isles were those of Walsall, Horsham and South-East 

 Edinburgh. These were insignificant, however, in comparison with the 

 earthquake that was centered below Belgium and shook more than 20,000 

 square miles of country in twenty-nine English counties on June 11, 1938. 



As a result of appeals for information through the daily press, three 

 wireless broadcasts and the distribution of numerous questionnaires, 

 856 reports have been gathered about this tremor from 278 towns in England, 

 the Channel Islands, France, and Belgium. Eight reports have been 

 obtained from seismological observatories in Britain and North-west 

 Europe. 



The tremor was noticed mainly by people at rest indoors. Positions in 

 the upper stories of high buildings were especially favourable. Particularly 

 in the east of the disturbed area at least two phases were distinguished, and 

 the motion was described as being a succession of smooth undulations in an 

 approximately east-west direction, conspicuously free from jerks. The 

 numerous accounts of apparent giddiness may be related to the smooth 

 wave-motion experienced. 



The only damage on this side of the Channel appears to have been a 

 single fall of a few tiles at Heme Bay, Kent. Appropriately-oriented pendu- 

 lum clocks were stopped in some cases, and in others, liquids were agitated 

 or spilled. Dogs, cats, and birds showed signs of alarm, and two reports 

 suggest that bees in open out-apiaries were so disturbed by the shock as to 

 have been unmanageable for a time. 



The area over which a sound was heard is ill defined, but does not seem 

 to extend far west of the longitude of London. Generally it was likened to 

 a rumble such as might be produced by the passage of a heavily-laden 

 lorry or train. 



After-shocks of the Belgian earthquake were recorded at Kew Observatory 

 on the same day at 12.10 and 13.9, and a much larger one on the next day, 

 June 12, at 13.26. Only the last of these was felt in England. It was 

 reported by nine observers. Mutually inconsistent reports of supposed 

 foreshocks and aftershocks were received from about a score of corre- 

 spondents. It is understood that Belgian seismologists place the epicentre 

 of the main shock near Ghent. The best precedent for tremors affecting 

 approximately the same area is the earthquake of April 6, 1580, which 

 caused considerable damage in Kent. The epicentre of that earthquake 

 is thought by R. E. Ockendon, the editor of the recent reprint of Thomas 

 Twyne's Discourse on the Earthquake, to have been near the Straits of Dover. 



Seismology at Kew Observatory. 



During the year the installation of the seismographs in a new under- 

 ground house was completed. The three Galitzin seismographs record on 

 one electrically driven clock drum, the two Wood- Anderson instruments on 

 another. A description of the installation is being published in a Memoir 

 written by Dr. A. W. Lee. It is satisfactory to be able to note that the 

 disturbances which affected so seriously the utility of the Galitzin seismo- 

 grams in windy weather, and which were attributed to the rocking of the 

 observatory, have no counterparts in the records obtained in the new 

 seismological building which is mostly below ground level. A number of 

 technical points with regard to Galitzin seismographs had to be investigated 



