84 REPORT—1850. 
“« But since it is manifest that exhalations must arise both from moist and dry 
places, when this is the case, earthquakes must necessarily occur. For the earth itself 
is by nature dry, but receiving much moisture on account of rain, when it is heated 
both by the sun and also by the fire which burns within itself, a great quantity of 
vapour must be produced both inside and outside of itself, and sometimes the 
whole of this flows uniformly inwards, sometimes outwards, and sometimes it is 
divided. 
“ΠῚ this then be necessarily so, the next point to consider is, what kind of bodies 
is most easily moved. But it is inevitable that what can go the greatest distance 
and what is most vehement should be specially of this nature. Therefore the most 
vehement is of necessity that which is borne along most rapidly, for it strikes with 
greatest violence on account of its velocity. For that naturally moves over the 
greatest space which can most easily move through everything, and such is the pro- 
perty of that which is most subtle. Wherefore since this is the nature of wind, it 
of all bodies is the most mobile. For fire, when it occurs along with wind, causes 
flame, and is rapidly borne along. Therefore neither water nor earth is the cause of 
earthquakes, but the exhalation of wind, when having flowed inwardly it has 
chanced to be exhaled outwardly. 
“Therefore the greater number of earthquakes and the most violent ones have 
taken place during calms ; for the exhalation being uniform, follows for the most part 
the impetus of its commencement, wherefore either all flows inwards together or all 
outwards. But that some earthquakes should take place during a wind is nothing un- 
reasonable, since we sometimes see several winds blowing at the same time, of which, 
if one be borne into the earth, there will be an earthquake while the wind is still 
blowing. But these are of less magnitude, since their origin and cause are divided. 
“* But earthquakes are also more numerous and greater in the night, and, of those 
in the day, about the middle of the day. For the middle of the day is in general 
the calmest part of it. [For when the sun has most power it keeps the exhalations 
bound in the earth, and it has most power in the middle of the day.] And the 
nights are even calmer than the days, on account of the absence of the sun, so that 
then the flow of wind is again inward, as if a regurgitation in an opposite direction 
to that in which the effusion took place ; and this especially towards dawn, when 
the winds usually begin to blow. If therefore the origin (or direction?) of them 
shall be changed within, as at Euripus, on account of their great mass the earth- 
quake will be the more violent. 
““ Karthquakes also seem to have been most violent about such places as are loose 
and full of cavities, and where the sea has many tides. Such are the places about 
the Hellespont, and Achaia, and Sicilia, and Eubcea, for about these places the sea 
seems to flow beneath the earth on account of the narrowness of the passage. For 
the same reason the hot baths near CEdipus were formed. 
“* Near all these places which we have mentioned the earthquakes are very violent 
on account of the narrowness ; for the wind being rendered violent on account of 
the great mass of the sea, which is borne to the land in great quantity, is repelled 
again back upon the earth, though naturally it should blow out from the earth. 
And thus those countries, the earth below which is spongy and therefore capable 
of containing much vapour, are more violently shaken. 
“In spring and autumn also the greatest earthquakes take place, both during 
drought and rain; but the winter and summer, the one by its cold, and the other 
by its droughts, produce immobility, for the one is too cold, and the other too dry. 
But even in droughts the air contains vapour (πνευματώδης ἐστὶ), for this is a drought 
when more dry than moist exhalations are produced. But during rain the wind 
causes a greater amount of exhalation within, and by this kind of secretion (ἀπό- 
kptovy) being intercepted in narrower places, and the same mass being driven into a 
smaller space, the hollow places of the earth being full of water; when it begins to 
have power, on account of a great mass being forced into a small space, the wind 
moving and striking produces violent motion. 
“For it is necessary to be understood, that as in our bodies the force of the wind 
which is intercepted is the cause of tremors and throbbings, so also the wind pro- 
duces similar effects in the earth, and one earthquake appears like a tremor and 
another like a throb, And as it often happens after a discharge of water (for then a 
τι  ——— 
