ME. E. D. OLDHAM OX A SEAS0^\1L YAEIATIOIS" [vol. Ixxvii^ 



which the most complete record was available in England ; and the 

 tabulation was confined to those earthquakes which originated 

 within the limits of Itah^ proper, excluding all those which 

 originated in the Alpine districts, or outside the limits, of Italian 

 territory. The number of earthquakes dealt with was 6607, and 

 an abstract tabulation by quarter days is appended to this paper. 



Taking the day and night halves of the solar and lunar day, the 

 number of shocks recorded in each, and the ratio of these numbers 

 to each other, come out as in the tabular statement below. 





SOLAB. 



LuiS'AE. 



ShocTcs 



Batio. 



SJwcks. . Ratio. 



1 

 Day. Night. 



Day. 



Night. 



Day. Night. Day. 



Night. 



Declination North 



Whole Record 



1440 1 2006 

 2733 3874 

 1293 ! 1868 



836 



827 

 818 



1164 

 1173 



1182 



1694 i 1667 1008 

 3269 3338 , 989 

 1575 1671 i 970 



992 

 1011 

 1030 



Declination South 



From these figures it appears that the same difference in tlie 

 ratio of cla}^ to night shocks, when the declination is north or 

 south, as compared with the general average ratio of the whole 

 period, is in the same direction in both solar and lunar tabulations, 

 and that the magnitude of the variation in the latter is about 

 double that found in the former, the actual ratio being 9 : 19 in 

 the solar and lunar tabulations respectively. As the ratio of magni- 

 tude of the corresponding gravitational stresses is about 9 : 21, 

 or practically the same as that of the variation in frequencv, 

 the figures may be taken as confirmatory of, and as giving a 

 considerable degree of probability to, the interpretation suggested 

 in the earlier communication. 



Distribution of Earthquakes in Italy, 1896-1914. 

 [Hour-angles are reckoned from the lower meridian passage.] 



Kour-Angles. 



0-6. 



6-12. 



12-18. 



18-24. 



Solar : 



Declination North 



1150 

 1032 

 2182 



790 



835 



1625 



710 



723 



1438 



824 



733 



1557 



730 



570 



1300 



870 



842 



1712 



856 



836 



1692 



877 



836 



1713 



Declination South 



Whole Record 



Lunar : 



Declination North 



Declination South 



Whole Record 





