Chapter VI: Book V: Treating of Winds and Movement of the Atmosphere

I. Definition of _wind_--air flowing in one direction. The
air, like the sea, is always moving, even when it is
thought to be still; hence the necessity of the additional
qualification--in one direction 193

II. Democritus says wind arises from a multitude of atoms in a
small space striving to get free, just like a crowd jostling
each other 194

III. But wind does not thus depend on density; cloudy or misty
weather does not necessarily produce wind, while wind is
produced when the morning sun dissipates the air. Democritus
is, therefore, wrong 195

IV. Wind arises in two ways--from the interior of the earth by
emission--like wind on the stomach!--and from evaporation 196

V. The air has inherent power of movement, which is the chief
cause of wind, evaporation being a less powerful one. Water
has the power of moving and of imparting life to animals and
plants 197

VI. Fire even, the destroyer, sometimes generates life. Air in
like manner has a peculiar power of its own 197

VII. _Breezes before dawn_ arise from rivers, etc. Do not last
long 198

VIII. _The “gulf” wind_ (ἐγκολπίας): its origin and duration 198

IX. Connection of winds with seasons of the year and with the
heat and light of the sun. The sun does not directly cause
the winds 200

X. Some cite the Etesian Winds as proof that he does. They blow
in summer when the snows melt and the moisture is carried
South 201

XI. But as to the effect of the sun, there is no analogy between
the Etesian Winds, which do not spring up till late in the
day, and the winds which rise at dawn and fall as the day
advances 202

XII. _Cloud squalls_ (ἐκνεφίας). Their formation and
combinations 203

XIII. The breaking up of clouds produces wind. Air, in an effort
to get free, or heat, may produce this. Interruption of free
passage may produce a whirlwind, just as an obstacle in a
river a whirlpool. _Violent whirlwinds_ take fire (πρηστήρ).
Some winds produce different ones. An analogy holds between
air and drops of moisture. A union of forces in air or in
dew is necessary to give impulse and produce a current. Air
and wind are merely a matter of degree 204

XIV. Mode in which the subterranean winds are generated and make
their escape 205

XV. Ancient miners of Philip’s saw rivers and vast underground
reservoirs. It is some consolation to read such a story,
which shows greed is no new vice: the older generations were
as reckless as we are in their quest for treasure better hid 207

XVI. The four _cardinal winds_. The full list includes twelve.
Their names and directions 208

XVII. The great circles of the earth which give twelve
divisions, and therefore prescribe the possible number of
the winds 210

XVIII. The uses of wind and the illustration afforded of the
wisdom of Providence. The crops are dependent on it. So
is commerce. But we make the sea a highway to war and
not to peace. We go to seek for death, as if it were not
always near. Xerxes, Alexander, Crassus are warnings of the
mischievous use of power to cross the sea. Better, perhaps,
the winds had never been given at all. But the value of a
natural gift must not be estimated by the depraved use of
it. Every gift, even sight and speech, man has perverted in
the same way 212