ON THE FACTS OF EARTHQUAKE PHENOMENA. 65 
searches however seems to be, that with respect to this relation of earth- 
quakes also, no law can be laid down. We must consider it as an 
established fact, that both earthquakes and volcanic eruptions may occur at 
any time of the day or year, since experience has shown this with respect to 
almost every time. The only question which remains on the subject is, 
whether we can ascribe to any one or other season or time, a greater ten- 
dency to produce or favour the production of such phenomena. A mere 
collection of facts, even though embracing a long period of time, would of 
itself hardly supply an answer to this question ; since, in order to draw to- 
lerably accurate conclusions from such a collection, many other circum- 
stances would have to be taken into consideration. We ought not to content 
ourselves with collecting and arranging a mere successive list of these phe- 
nomena, but on the contrary, we should compare with one another only the 
most considerable, and those which occurred in the same climate, with other 
precautions of a similar nature. That, however, the motions (Bewegungen) 
which are always going on, in the inner portions of the earth, are at certain 
times much more energetic and more continuous than at others, numerous 
examples testify. There have been periods of many years in which these 
motions remained continuously violent and widely spread, as from 1666 to 
1694, 1749 to 1768, &c.; and others in which for several years they seldom 
manifested themselves. On the whole, however, if it be probable that the 
idea of any influence exercised by the atmosphere upon the volcanic process 
should be considered as overturned, the opinion of the influence of the time 
of day or year upon the occurrence of earthquakes, &c. will retain but little 
probability.” (Von Hoff, Gesch. Verand. Erdober, Th. iv.) 
Seneca, ‘ Quest. Nat.’ vi. c.1; a writer in the ‘ Annal. de Chim.’ vol. xlii. 
p- 416 ; Cotte, in ‘ Journ. de Phys.’ for 1807, p. 161; and Hoffman, ‘ Hin- 
terlassene Werke,’ Theil 11, have discussed the question as to whether earth- 
quakes are more frequent at one season than at another. Kant, in his ‘ Phys. 
Geogr.,’ vol. ii. p. 199, thinks they occur chiefly in the spring and fall of the 
year. Smith, in his ‘Memoirs of Sicily,’ p. 6, states, that thirteen earthquakes 
occurred there betwixt the 10th of January and the 28th of the succeeding 
March. Shaw, in his ‘ Travels in Barbary,’ p. 152, comes to the conclusion 
that they are most frequent there at the end of summer and iu autumn. All 
these however are observations on far too narrow a basis. 
' Hoffman, ‘ Hinterlassene Werke,’ xi. 357, and Kries, ‘ Ursachen des Erd- 
_ beben,’ p. 8, have givena large catalogue of earthquakes during the Christian 
epoch. Arago, in ‘ Annal. de Chim.’ xlii. p. 409, has discussed the earth- 
_ quakes of forty years at Palermo. Pouqueville has given a list of sixty-three 
earthquakes at Joannina from 1807 to 1825. Cotte gives a list of 338 
earthquakes in the ‘Journ. de Phys. for 1807. Hoffman has compared 
_ these with the forty years’ earthquakes of Palermo (Poggen. Annal. xxiv. 52, 
and xxxiv. 104), and Von Hoff (whose great ‘Chronik der Erdbeben’ has 
never yet been fully discussed) has compared all these with those for the 
years 1821 to 1830, occurring in the northern hemisphere. And Merian 
_ (Uber die in Basil Wahrgenommenen Erdbeben’) has given a list of those oc- 
_ curring at Basil. All these the author of the able article Erdbeben (L. F. 
|  Ka&amtz) in the ‘ Allgemeine Encyklopadie der Wissenschaften und Kunste,’ 
~ von Ersch und Gruber, Theil 36, has arranged in the following table by 
| months, adding the sum in another column :— 
: 
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| 
