Chapter II: Preface: Page

Contrast between human (moral) philosophy and divine (natural,
physical). The sublime character of the latter which lifts
us above the contemplation of the littlenesses of the earth
and earthly life to the knowledge of God and His nature.
Compared with astronomical conceptions and dimensions the
world of man is but as a threshing-floor, the haunt of ants.
The mind of man attains its true height in contemplation and
investigation of these sublime facts. Some of the problems
thus raised 3

CHAP.

I. Meteoric fires--_she-goat_, _kid_, etc. Occasions of their
appearance; connection of portent with event. Explanation
of the phenomena. They may be due to pressure of the
atmosphere. Aristotle attributes them to the effect of
terrestrial evaporation: difference of density causes
various outbursts of this kind. They are analogous to
lightning, but less violent 8

II. _Halos._ Produced by the light of a heavenly body striking
the surrounding air and forming a circle as a stone does
when thrown into a pond. Formed far away from the heavenly
body and comparatively near the earth in the region of the
wind. Require a particular state of the atmosphere neither
too dense nor too thin. More frequent at night than day for
this reason: by day the sun rarefies the air too much by
its heat. Method of dissipation gives indication of wind or
rain. Calmness a condition of formation, as in the analogous
case of water 12

III. _Rainbows._ Generally by day, produced by inequalities
of surface and density in clouds. Another species seen in
a burst pipe or a fuller at work. Various explanations.
Light and shade will not explain the varied colours. Some
explain the rainbow as a confused reflection of the sun
from individual drops of rain: every bounded surface, large
or small, thus reflects--fish-pond and dew-drop equally.
Aristotle attributes the confusion of colours to weakness of
human sight; parallels may be found in persons whose sight
is abnormally weak. As the innumerable drops, apparently
without intervals, fall, human vision fails to distinguish
severally the reflections of the sun, which thus become
blended and confused. Vision is similarly deceived in the
case of an oar in water, apples in a glass globe, etc., even
in the size and movements of the sun himself. At any rate
the rainbow requires both sun and cloud, and these opposite
to each other. These two in operation produce the varieties
of colour 16

IV. That the rainbow is an image is shown by the relation of
sun to cloud in position, by the rapidity of formation and
dispersion. Artemidorus’ explanation of the shape of the
cloud (concave), and the consequent position of the red in
the rainbow 22

V. Arguments to show that the cloud is coloured by the sun,
like a dove’s neck or a peacock’s tail, and that the rainbow
is not a _reflection_ of the sun. The position (opposite)
would be equally necessary in this case. Answer to this
contention by Posidonius. The colour effects. Author agrees
with Posidonius’ position but not his arguments. The only
_proof_ is the geometrical one 23

VI. Arguments from the size--never more than a semicircle--and
shape of the bow. As the colour, whether real or reflected,
is derived from the sun, so must also the shape be. The size
is accounted for by the magnifying power of water, glass,
etc. The sun as he appears in the rainbow is seen through
moisture 28

VII. The arguments from the dispersion of the sun’s rays through
glass (prism). Contention that they confirm author’s view 30

VIII. The form once more; why it is never larger than a
semicircle. A wrong explanation refuted. Explanation of
Aristotle’s remark as to the seasons of rainbows, in summer
only in the morning or evening, in autumn at any time 31

IX. _Streaks_ or _weather-galls_. Merely abortive or imperfect
rainbows 33

X. Relations and differences of _halos_, _bows_, and
_weather-galls_ 34

XI. _Mock suns._ Their appearance and position in relation to
the sun. They are a reflection of the sun in a suitable
medium 34

XII. The formation of a mock sun may be compared to the image
of the sun in eclipse as seen reflected in a dish of oil or
pitch: the medium must be adapted to give the impression.
The mock sun requires a certain consistency of cloud,
failing which, a different effect is produced--obscuration,
dissipation, etc. 35

XIII. There may be two mock suns simultaneously. Some think
the one is a reflection of the other, the clouds acting as
mirrors set opposite to one another. Mock suns, especially
in the South, are a sign of rain 36

XIV. Other celestial fires. “_Cave meteors_,” “_Barrel
meteors_,” “_Chasms_,” with a brief description of each. The
rapidity of their flight, just as of lightning, deceives the
sight. Their origin and cause. They indicate wind 37

XV. _Gleams_ (_flashes_, σέλα). Their production and motions,
varieties of them. Some do damage. Some are analogous to
comets. “_Bearded_,” “_torches_,” “_cypress_” are different
kinds. “_Beams_” and “_barrels_” may be of the same class.
A curious case where such an appearance raised an alarm of
fire. They are real fires. On the contrary, rainbows and
halos are mere reflections. Mirrors have this wonderful
power of false presentation 39

XVI. The “mirrored den” of Hostius Quadra 41

XVII. The philosophy of the looking-glass. The evolution of
mirrors. Mirrors of full length are now used. They cost a
fortune greater than the Senate gave Scipio’s daughters.
A harmless necessary device has become an instrument of
luxury, the adornment of women, the burden of men, nay, part
of the kit of the soldier 44