56... REPORT—1858. 
ledge, both of seismic and volcanic phenomena, leads to the conclusion of 
foci very much nearer the existing surface; and the diagram may be re- 
garded as conclusive evidence that these presumed coincident earthquakes 
at very distant points, even if proved simultaneous, are unconnected, and 
have different origins. 
In the most singular case on record, that of Ochotzk and Quito, places 
nearly antipodal, the common origin would actually be in, or not remote 
from, the earth’s centre ; and it is not conceivable that the shock, which, if 
sufficiently powerful, must in such cases be felt nearly simultaneously over 
the whole globe, should have been confined to the two extremities of a single 
diameter. 
In recapitulation, it may be convenient to give in numbers, for occasional 
reference, a few of the salient results of the distribution in time, already 
i discussed :-— 
so No. of No. of 
Earthquakes. Years. 
Total number of recorded earthquakes up to A.D..... 58 1700 
Total number from A.D. to end of the ninth century.. 197 900 
Total number from the beginning of the tenth to the 
end of the fifteenth century .................. 532 600 
Total number from the beginning of the sixteenth to 
the end of the eighteenth century.............. 2804 300 
Total number from beginning of nineteenth century to 
the end ‘of the yedr Wa rae ig cs wien cleo = 3240 50 
Total Catalozue.. . <ssis0darnns tobe oe. els vileveewan GboL 
The number of great earthquakes (7.e. those, as already defined, in which 
whole cities and towns have been reduced to rubbish, many lives lost, &c.) 
have been but imperfectly exhibited graphically, and not at all for the later 
centuries, from their too frequent recurrence making their notation difficult 
or confused ; they are here given numerically. 
Number of great earthquakes from third century B.c. to beginning of 
DUNG) old We ROME. 3 Sead ode Se SO eee Panioo oe 6 0s, os /sfeleioua oleate 
Number of same from .p. to the end of the ninth century ........ 15 
Number from beginning of the tenth century to the end of the fifteenth 
CONUITY ios ole eiek see tee SE Ada Been eeoe 25% - Biotic: oo, Ak 
Number from beginning of the sixteenth century to the end of th 
ele hteenth Century. '2 © - sexy ee es les, obs stein Sen erence ae oa sieratnace, eid 100 
Number from beginning of the nineteenth century to 1850 ........ 53 
Total c ssnoit dari ce 
If we double the last number but one, to embrace the entire 100 years, the 
correspondence between the results for the two last periods is remarkably 
close, viz. 100 and 106,—and although the series is still an expanding one, 
yet as the numbers for the 16th and 17th centuries are not large; it is 
probable that for the last 150 years at least, our news of all great earthquakes 
have been complete, and the cataloguing of them perfect, showing that at 
present we may calculate upon 1:37—say 1*4, or nearly 14 recurrences of 
great and disastrous earthquakes every year, at some one or more places on 
the earth’s surface, or one great earthquake disaster every eight months. 
