ON SEISMOLOGICAL INVESTIGATIONS. 93 
winter (October 81 to March 31) to those noted in summer in these 
three districts were respectively 1 to 0°55, 1 to 1:08, and 1 to 1:20. 
In the following tables these comparisons are continued from the 
year 1906 to the year 1910 :— 
< . . s “3 b o ib ~~ a 3 : 
Districts a 2 a ee s Z a 2 3 & Zz 3 Total 
ABC) 1906.) 3) Wy) oBlo Selo Vl Pl wl eo} Ol eo OF} 013 
ROWE | OapsiGusck | oO Gi OF Ta, Br O.),.0 6 
1908:| 0, 1b 0.1 0.) Bae 0} 0) OF}. 0). 1+) 1 10 4 
EGO Gn | eOL Gat |) 2101-2) FiO; rl oO 7 
ROTO tO!) Pe Pelayo OT Te on oneal’ t9 
Hatala ede Sy lew4 iG |wiSulb Ae heyAeleed: (dd | 4h. 7 | 1]. 42 
Bees eo | 3] 6 6.2) 4) PP os) 5 | Sl 61 Ol) 49 
NGO ores del tss) SQN igs ett pel pel Be Feces) tag 
HOOS esse oS Sule 2! 1) Ph ye.3) ae wo ise 
WOOOL estes) lotta TT Lect lO: 2 Gall aSe\| 2 ssa gul 6s 
TSTON ee eS | ON eres 11 (e287 43 | Mel |) a aes 
Total | 20 | 13 | 21 | 25 | 31 | 27 | 13 | 17| 20 | 19 | 14 | 27 | 257 
Pee mies! 1 | pilol| op} ato! 3) xl. alae 
TOO Ta lela Onl le | toh Onl -Oe). Oe | 3h Gat 16 
LOOS eae POS) |) CBee el ae PAs leer). | age) e Oulvegh| ag 
EOOB | US fe Sol ee ts Bets Ble AG che le ie cholic Balethe| 201 3 
AOLOO | We ety ee On sk esa & (ae ad |) 85) |, ok) 233 
Total | 6| 7 | 8 | Sr ere do 19 |G | 14s |e on red 
Earthquakes Earthquakes 
in Winter in Summer Ratio 
Districts A, B,C. . : : é Sea 17 / 25 1 to 1°47 
me Be oe . 124 133 1 to 1:07 
District K. ‘ ‘ ‘ a . PeAD 59 1 to 1:31 
These results suggest that the greater number of large earthquakes, 
whether they originate beneath an ocean or beneath a continent, occur 
in summer, and a similar result is arrived at if we assume that summer 
commences on May 1 rather than on April 1. 
It must, however, be noted that for A, B, C between 1899 and 1905 
the greater frequency was found in the winter months. With this 
exception the results here given accord with those obtained previously. 
If we combine these three districts for the twelve years ending 1910 
we find that 365 earthquakes have taken place in the summer and 349 
in winter, the winter to the summer ratio therefore being 1 to 1:04. 
This close correspondence between winter and summer frequency 
suggests that megaseismic frequency is but little influenced by epigenic 
phenomena which follow the six-monthly changes in climate. The 
observation that between 1899 and 1905 the greater frequency was in 
winter, while subsequently it was in summer, also suggests that mega- 
seismic frequency is not related to our seasons, and if there is a 
seismic periodicity it must be sought for outside seasonal recurrences. 
Frequency in the World, 1899 to 1909.—In eleven years, or 4,018 
