ON SEISMOLOGICAL INVESriGATION. 



99 f. 



is photogi-npliic, and shows the movements of a pair of von Rebeur pen- 

 dulums. It has yet to be described. 



In the following few examples of records referring to period the fol- 

 lowing abbreviations are used : — 



Pt. = Preliminary tremors, the periods of which arc expressed in seconds. 



Lw. = Large waves, „ „ ., ,> 



P. = Simple pendulum, the length of which is given in metres. These 



pendulums have multiplying indices. 

 H.P. = Horizontal pendulums. 

 G.L.^Geodynamic level (see p. 263, also ' B.A. Eeport,' 1896, p. 227). 



The first name refers to the place at which a given earthquake 



originated. 



1895. 



Jan. 18. 

 July 8. 

 Aug. 9. 



189G. June 15. Japan. 



Aug. 31. Japan. 



Sept. 6. Iceland. 



Jap.Tn. At Rome P. 16m. gave for Lw. 16-4s. 



Caspian Sea. „ IschiaG.L. „ „ „ 22s. 



E. Italy. „ Rome P. 16m. „ „ „ 8-8s. and Pt. -IGs. 



Rocca di Papa P. 7m. gave for Lw. 7s. 

 Padua P. gave for Lw. 40s. 

 Ischia H.P. (with a natural period of lis) 

 gave Pt. 6s. to 12s., and Lw. 20s. to 50s. 

 „ Catania gave Pt. 3s., Lw. 15-5s. 

 „ Rome P. 8m. gave 21s.. P. 16m. 14s. to 20s. 

 1896. June 29. Cyprus. ,, Ischia H.P. gave Pts. 4s., Lw. 10s. 



„ Rocca di Papa P. gave Pt. 4s., Lw. 6s. 

 „ Aug. 26. Iceland. „ Rome P. ICm. gave liW. 10s., P. 8m. gave 



Lw. 10s. 

 „ Rocca di Papa P. 15m. gave Lw. 14s., P. 7m. 



gave Lw. 14s. 

 ,, Ischia H.P. gave Lw. 18s. 



Ischia H.P. gave Lw. 60s. down to 1 3s. 

 Rocca di Papa H.P. Lw. 30s. to 14s., P. m 



gave Lw. 14s., P. 15m. 30s. and 14s. 

 Rome P. 16m. 8s. to 13s. 

 Catania P. Lw. 48s. to 72s., Pt. 14s. to 2Ss. 

 Rome P. 16m. gave ll'Ss. 

 Catania Lw. 15s. to 18s. ; also 8s. to 16s. 

 Rocca di Papa P. 15m. gave 14s., H.P. gave 



16s., P. 7m. gave 16s. 

 Ischia H.P. 2 2s. to 17s. 

 Ischia H.P. gave Pt. 2-5s., Lw. 19s. 

 Rocca di Papa H.P. gave about 17s. 

 Rocca di Papa H.P. gave 18s. 

 Ischia H.P. 6s. to 25s. 



1897. Jan. 10. Persian Gulf. „ Padua P. gave 35s. to 16s., Ischia H.P. gave 



25s. to 12s. 



Catania P. 25m. gave 6s. to 18s. 

 Shide H.P. gave 15s. 



When reading the above records it must be remembered that they 

 refer to the shortest and longest periods which were observed, or to waves 

 with the smallest and largest amplitudes. Near to an origin, after a 

 shock, a disturbance dies out with an increasing period, but at a great 

 distance from an origin the maximum movements which probably corre- 

 spond to a shock or shocks are those which have the longest period. 



Also the fact must not be overlooked that the records refer to seismo- 

 grams obtained from different instruments, located at different stations, 

 and that it is not certain that comparisons are made between similar 

 phases of motion. The following table is therefore tentative, and when 



1898. Q 



