The reason why : $b a careful collection of many hundreds of reasons for things which, though generally believed, are imperfectly understood. A book of condensed scientific knowledge for the million
John Stuart Mill · en
Because the electrical state of the atmosphere has the effect of making
them feel uneasy and irritable, and _they chase each other about to get
rid of the irritability_.
1123. _Why if birds of passage arrive early, may severe weather be
expected?_
Because it shows that the indications of unfavourable weather have set
in, in the latitudes from which the birds come, and that they have
_taken an early flight to escape it_.
1124. _Why if the webs of the gossamer spider fly about in the autumn,
may east winds be anticipated?_
Because an east wind is a dry and dense wind, and suitable to the
flight of the gossamer spider; the spider feeling instinctively the
dryness of the air, throws out its web, and finds it _more than usually
buoyant upon the dense air_.
The observation of the changing phenomena which attend the various
states of the weather is a very interesting study, though no
general rules can be laid down that can be relied upon, because
there are modifying circumstances which influence the weather in
various localities and climates. To observe weather indications
accurately, no phenomenon should be taken alone, but several
should be regarded together. The character and the duration of
the weather of the preceding days, the direction of the wind,
the forms of the clouds, the indications of the barometer, the
rise or fall of the thermometer, and the instinctive forewarnings
of birds, beasts, insects, and flowers, should all be taken
into account. Although no direct material advantages attend
such a study, it induces a habit of observation, and develops
the inductive faculty of the mind, which, when applied to more
significant things, may trace important effects to their greater
causes.
[Verse: "Go to the ant, thou sluggard; consider her ways, and be
wise."--PROV. VI.]
CHAPTER LVII.
1125. _Why can gossamer spiders float through the air?_
Because, having no wings, and being deficient in the active muscular
powers of other spiders, they have been endowed with the power of
spinning a web which is so light that it floats in the air, and bears
the body of the gossamer spider from place to place. Each web acts as a
balloon, and the spider attached thereto is a little _aeronaut_.
1126. _Why do crickets make a peculiar chirping sound?_
Because they have hard wing cases, by the friction of the edges of
which they cause their peculiar noise, _to make known to each other
where they are_, in the dark crevices in which they hide.
[Illustration: Fig. 74.--GLOW-WORM USING HIS BRUSH.]
1127. _Why has the glow-worm a brush attached to its tail?_
Because it is necessary to keep its back very clean, that _the light
which its body emits may not be dimmed_.
1128. _Why does the glow-worm emit a light?_