Vol. 62.] OF THE INTERIOR OF THE EARTH. 459 



II. The Data. 



In dealing with the data, it is necessary to make some selection 

 from the large amount of material which has been collected, and to 

 confine our attention to those records in which accuracy \$ prima- 

 facie probable ; this limits us to those earthquakes the place and time 

 of origin of which can be determined with accuracy, and which were 

 also of sufficient magnitude to give complete records on distant seis- 

 mographs. This last reservation is necessary, for many earthquakes 

 of great local severity are only imperfectly recorded at a distance 

 of even a quarter of the circumference of the globe, and the portion 

 lost is always that of the preliminary tremors. 



These limitations leave only fourteen disturbances for consideration, 

 some of which consisted of two or three distinct earthquakes, starting 

 from the same origin at short intervals from each other. Of these, 

 details have been published in a collected form in some cases only, 

 in the others they are still in manuscript ; but those that have been 

 published will serve to show the manner in which scattered details 

 are grouped and dealt with. The earthquakes utilized in this 

 paper are : — 



1. Japan, March 22nd, 1894 ; 10 h 22"5 m , 43 Ol K, 146°'0 E. Phil. Trans. Eoy. 

 Soc. ser. A, vol. cxciv (1900) pp. 139-40, quoting Peterm, Mitth. vol. xli (1895) 

 pp. 14-21. 



2. Argentine, Oct. 27th, 1894; 20 h 55'5™ 28°"5 S., 69 o> W. Ibid. pp. 140-142. 



3. Japan, June 15th, 1895 ; three shocks, 10 h 3rO m , 19 h 3-2 m , 22 h 58'0 m , 

 39 0, 5 N., 144°"5 E. Ibid. pp. 142-145, with some further details from Beitrage 

 zur Geophysik, vol. vi (1903-1904) p. 408. 



4. Japaii, Aug. 31st, 1896 ; 8 h 7'l m , 39°"7 K, 140°-8 E. Ibid. pp. 145-47. 



5. India, June 12th, 1897 ; ll h 5'0 m , 26° ST., 91°'0 E. I'nd. pp. 147-49. 



6. Japan, Aug. 5th, 1897 ; h 9-4 m , 39°'5 N., 144°-5 E. Ibid. pp. 149-51. 



7. Turkestan, September 17th, 1897 ; two shocks, 15 h 28"0 m , 17 h 36-0 m , 

 39°-0 N., 68°-0 E. Ibid. pp. 151-55. 



8. Japan, April 22nd, 1898 ; 23 h 34-2 m , 39° -5 N., 143°-0 E. MS. 



9. Japan. August 9th, 1901 ; two shocks, 9 h 23'5 m and 18 h 33-5 m , 40°-5 N., 

 141° 5 E. MS. 



10. Philippines, Dec 14th, 1901 ; 22 h 57'5 m , 13°5 N., 12P25 E. MS. 



11. Guatemala, April 19th, 1902 ; 2 h 22"0 m , 14°'5 N.. 91°-25 W. Proc. Eoy. 

 Soc. ser. A, vol. lxxvi (1905) pp. 102-111. 



12. Kashgar, August 22nd, 1902 ; 3 h TO" 1 , 39°-5 N., 75°'9 E. MS. 



To which may be added two earthquakes the time of origin of 

 which is only known by inference from distant records, as men- 

 tioned lower down : — 



13. Alaska, September 4th, 1899, h 20\o m ; September 10th, 17 h P5 m and 

 21 h 39-5 m ; about 59°-5 N., 140°-0 W. MS. 



14. Ceram, September 29th, 1899, 17 h 3'0 m , 3°-5 S, 128°-5 E. MS. 



In dealing with the records, it is necessary to bear in mind that 

 they are liable to certain errors. In the first place, many earth- 

 quakes consist, not of a single impulse only, but of two or more, 

 separated from each other by intervals of some minutes ; and it is 

 not uncommon for the disturbance due to the first impulse to be 

 overlooked, either because it fails to overcome the inertia of the 

 instrument, or because the disturbance is too small to be recognized. 



