1166 
MR. C. DAVISON ON THE ANNUAL 
84. It will be seen, on examining the above tables, that the amplitude of the 
annual period is small in several countries which are g’enerally regarded as earth¬ 
quake countries. In some cases, this is no doubt due to the definition of the unit 
earthquake. Again, when the area is a wide one, the amplitude may be small, 
owing to the maximum ej)Och for different districts occurring at different dates. 
Partly to this, perhaps, is due the apparently small amplitude in the Northern 
Hemisphere (Mallet), Italy (Fuchs), and New Zealand (Hector and Hogben). 
Lastly, the amplitude is small in some insular districts, for example, Japan (’08) and 
New Zealand (’05 or ’06). 
85. Semi-Annual Period .—Of the 62 records examined, only three fail to show a 
fairly well-marked semi-annual period, namely, France (Fuchs), Spain and Portugal 
(Perrey), and Chili (Fuchs) ; these failures also being probably due to incomplete¬ 
ness in the seismic record. Different records for the same district do not always 
agree in giving the same epoch for the maximum of the semi-annual period; for 
example, those of the Northern and Southern Hemis23heres, Europe and the West 
Indies, As a rule, however, the agreement is fairly close. And this is also especially 
true in the case of districts adjoining and overlapping one another; for example, 
Austria, Hungary, and Switzerland and the Tyrol (Fuchs) ; South-east Europe 
(Perrey, Schmidt) and the Balkan Peninsula (Fuchs) ; CalifoiTiia, San Francisco, 
and San Jose and Santa Clara (Holden); India (Oldham) and the Malay Archi¬ 
pelago (Fuchs) ; the different districts of New Zealand (Hector) ; and also Tokio 
(Milne) and Yokohama (Streets), for the short period 1878-1881. Excluding 
doubtful cases, the distribution in time of the maximum epochs is given in the 
following table:— 
Northern 
hemisphere. 
Equatorial 
countries. 
Southern 
hemisphere. 
January, a, and July, a .. . 
4 
1 
1 
Januaiy, h, and July, h . . . 
0 
0 
0 
February, a, and August, a . 
4 
LI 
-i 
February, b, and August b . 
d 
0 
0 
March, a, and September, a . 
.5 
1 1 / 
3 
March, h, and September, h . 
0 
0 
April, a, and October, a .. . 
5 
0 
0 
April, h, and October, b . . . 
2 
0 
0 
May, a, and November, a .. . 
0 
0 
1 
May, b, and November, b . 
0 
0 
0 
June, a, and December, a 
8 
0 
1 
June, b, and December b . . . 
o 
w 
0 
0 
In New Zealand and the south-east of Australia, the maximum epoch falls most 
frequently in February or March, and August or September ; in Noi'th America it 
usually occurs in March or April and September or October. I have not been able 
