Vol. 52.] SEISMIC PHENOMENA IN THE BRITISH EMPIRE. 651 



38. Seismic Phenomena in the British Empire. By M. F. de 

 Montessus de Ballore, Officer commanding the Garrison 

 Artillery at Nantes. (Translated by L. L. Belinfante, B.Sc, 

 B. es L. Communicated by Sir Archibald Geikie, F.R.S. 

 Bead June 10th, 1896.) 



[Abridged.] 



[Plates XXX.-XXXIII.] 



I. Introductory. 



Without pretending to have discovered the primary cause of earth- 

 quakes, the author is firmly convinced that the plan which he has 

 been elaborating for some years will reduce the present chaos of 

 seismological study to some sort of order, and will enable others to 

 go farther than he has done. This plan is made up of four parts, 

 and the present paper, which deals with the British Empire, is a 

 section of the third part now approaching completion. These four 

 parts, three of which will be briefly outlined in the following 

 pages, are : — 



(1) Formation of an Earthquake Catalogue. 



(2) Refutation of the empirical laws previously enunciated. 



(3) Description of the globe from the seismic point of view. 



(4) Study of seismic phenomena in the United Kingdom and the 

 British Colonies. 



II. Formation of an Earthquake Catalogue. 



More than 100,000 observations of earthquakes have been brought 

 together, 6175 of which have been made use of in the present work. 



These observations vary much in value ; when they are the result 

 of isolated narratives, gathered from documents of all kinds (but the 

 object of none of which is the special study of earthquakes), we get 

 so-called ' historical series,' generally of little account. If, on the 

 other hand, scientific men have especially busied themselves with 

 these phenomena in auy particular country, and have taken careful 

 note of the earthquakes felt by them or reported to them, we get 

 so-called ' seismological series ' whose value is the greater the 

 larger the number of years covered by them. Then too some countries 

 are equipped with special observatories containing self-registering 

 .seismographs ; these furnish so-called ' seismographical series ' of 

 very considerable value. It has, however, been shown that these 

 series are not absolutely reliable, because the apparatus being too 

 sensitive and being placed too near great centres of population is apt 

 to register all sorts of vibrations, some of which are due to the 

 passage of heavy railway-trains, or to operations connected with the 

 laying of roads, of gas- and water-mains, etc., and have, of course, 

 nothing to do with true seismic movements. 



Q. J. G. S. No. 208. 2 r 



