ON SEISMOLOGICAL INVESTIGATION. 59 



Seismologieal Investigations. — Fifth Report of the Committee, coii- 

 sisting of Professor J. W. Judd (Ghairman)^ Mr. John Milne 

 (Secretary), Lord Kelvin, Professor W. G. Adams, Professor T. G. 

 BoNNEY, Sir F. J. Beamwell, Mr. 0. V. Boys, Professor G. H, 

 Darwin, Mr. Horace Daravin, Major L. Darwin, Professor J. H. 

 EwiNG, Professor C. G. Knott, Professor E. Meldola, Mr. R. D. 

 Oldham, Professor J. Perry, Mr. W. E. Plummer, Professor J. H. 

 PoYNTiNG, Mr. Clement Reid, Mr. Nelson Richardson, the 

 late Mr. G. J. Symons, and Professor H. H. Turner. 



[PLATES II. AND III.] 

 Contents. 



I'AUE 



I. On Seismolof/loal Stations abroad and in Great JBritidn . . , ,59 

 II. Analyses vf JUarthqualies recorded in 1899. By J. MiLNE. 



1. Nature and Ohjcots of these Analyses 60 



2. Velocities of Eartliqualte Waves ........ 61 



3. Errors affecting such Determinations 62 



4. Velocities for Preliminary Tremors or P. T.'s 63 



5. Velocities for Large Waves or L. TF.'s 64 



6. Intervals between P. T.'s and L.W.'s 65 



7. Earihquahe Recurrences 66 



K. Am,2}litude in relation to Continental and Sub-oceanic Paths . . 69 



9. Arcual Velocity in relation to Surface Confignration . . . .70 



10. Earthquake Echoes 71 



11. The Nature of Large Waves 73 



12. Criticisms and Analyses by Br. C. G. Knott 74 



13. Betermination of Origins 78 



By comj)arisons between time intervals 79 



By method of circles 79 



By time intervals between P. T.'s and L.W.'s . . , . .79 

 By seismic recurrences ......... 80 



14. The Origins for the Earthqualtes o/"1899 80 



15. Illustrations of Seismograms 87 



III. Earthquakes and Timekeepers at Observatories. By J. Milne . . . 103 



IV. Earthquakes and Rain. By J. Milne 106 



V. Earthquakes and Changes in Latitude. By J. MiLXE .... 107 



VI. Selection of a Fault — Locality suitable for Observations on, Etrth-move- 



vients. By Clement Eeid 108 



VII. On the Relative Movement of Strata at the Ridgeway Fault. By Horace 



Darwin 119 



I. On Seism,ological Stations abroad and in Great Britain. 



In addition to the twenty-three stations referred to in the Report for 

 1899 instruments have been ordered for the Observatory, Melbourne, 

 the Observatory, Sydney, N.S.W., for Ceylon, for the Johns Hopkins 

 University, Baltimore, the Liverpool Observatory, Bidston, and the 

 Royal Observatory, Edinburgh. The total number of similar installa- 

 tions which may be expected to be in working order before the end of 

 the current year will therefore be twenty-nine. The positions of these 

 are shown on the map (Plate II.). 



Registers ending December 31, 1899, referring to Shide, Kew, Cal- 



