ON SEISMOLOGICAL INVESTIGATIONS. 65 
Those stations which are in or near to areas in which large earih- 
quakes radiate, as, for example, Batavia, Manila, and Osaka, should 
obtain more records than Toronto, Ottawa, and St. Louis, which are 
distant from sites of seismic activity. For this reason stations have 
been grouped according to their relative distances from seismic regions. 
The first group refers to stations in the British Isles, Central and 
Western Europe, the second group is in North America, and the 
third group is India, the Western side of the Pacific, Australia, and 
New Zealand. 
The average number of records obtained in these three districts 
is respectively 58, 29, and 41, but why the average for the first 
of these districts should exceed that for the last is contrary to expec- 
tations, and to explain it we must look for something more than 
nearness to or distance from epicentral regions. 
If we consider the average number of records given by different 
types of instruments in different districts, the results we arrive at are 
as follow :— 
In District 1 the average number of photographic records was 69 
3 1 - smoked-paper 3 55 
Pe 2 3 photographic 3 35 
a 2 ie smoked-paper a 13 
“ 3 of photographic . 39 
ae 3 = smoked-paper 33 45 
Districts 1 and 2, together with records from Cairo, Tiflis, and 
Reykjavick, indicate that with photographic recording apparatus more 
records can be obtained than with mechanical registration. The same 
is true if we take all the records, including those for District 3, en bloc, 
but for this latter district by itself the conclusion is reversed. 
If we next turn to the character of the foundations we find for 
Districts 1 and 3 that the average number of records obtained if this 
was rock was 52, but where it was alluvium it was 50. 
Other observations bearing upon this subject will be found in 
British Association Reports for 1901, pp. 43 and 51; 1902, p. 68; 
1903, p. 81; and 1904, p. 42. 
XIII. Seismic and Volcanic Activities. 
In the Report for 1912, p. 102, I pointed out the material in 
certain catalogues suggested that volcanic and seismic activities in 
the world increased and decreased independently of each other. From 
this it might be inferred that if there is any periodicity in volcanic 
activity it would not be the same as the one exhibited by the 
megaseisms. With the object of examining this question more closely 
I asked Mr. Leo Kelley, of Dublin, who has made an extensive 
collection of materials in connection with volcanoes, to furnish me 
with a list of eruptions which have taken place during the last 200 
years. This he kindly did, but unfortunately in many instances the 
authors from whom he has quoted only mention the year in which 
an eruption took place and omit the month and date. In the first 
1913. F 
