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 _sensitiveness_ of the nerves of the ear becomes deadened.
They do not convey to the brain such intense impulses when they are
frequently acted upon by loud sounds.
991. _Why do persons engaged in battle often lose their hearing?_
Because the vibrations caused by the sounds of artillery are so violent
that they overpower the mechanism of the ear, and frequently _rupture
the connection of the fine nervous filaments_ with the textures through
which they spread.
The violent concussions of the air produced by volleys of cannon,
or by loud peals of thunder, have an overpowering effect upon
persons nervously constituted, and upon the organ of hearing,
which is more especially affected. As persons have been struck
blind by intense light, so others have been deafened by intense
sounds. In 1697 a butcher's dog was killed by the noise of the
firing to celebrate the proclamation of peace. Two troops of
horse were dismounted, and drawn up in a line to fire volleys. At
the moment of the first volley a large and courageous mastiff,
belonging to a butcher, was lying asleep before the fire. At
the noise of the first volley the dog started up, and ran into
another room, where it hid itself behind a bed; on the firing of
the second volley, it ran several times bout the room, trembling
violently; and when the third volley was fired it ran around once
or twice with great violence, and then dropped down dead, with
blood flowing from its mouth and nose. Persons who are painfully
affected by loud noises should put a little wool in their ears
when such noises are occurring; they will thereby save themselves
from temporary inconvenience, and probably preserve the sense of
hearing from permanent injury.
992. _Why do we smell?_
Because minute particles of matter, diffused in the air, come in
contact with the filaments of the _olfactory nerve_, which are
spread out upon the walls of the nostrils, and those nerves transmit
impressions to the brain, constituting what we call the _odour of
substances_.
[Verse: "And the Lord God formed man of the dust of the ground, and
breathed into his nostrils the breath of life; and man became a living
soul."--GENESIS II.]
[Illustration: Fig. 66.--SHOWING THE DISTRIBUTION OF THE NERVOUS
FILAMENTS UPON SENSITIVE MEMBRANES.]
A. The _olfactory nerve_, distributed in minute branches upon the
membrane of the nostril.
B. The _bulb_ of the _olfactory_ nerve.
C. The _roots_ from which the olfactory nerve originates.
D E. _Nerves of the palate_, showing the manner in which they are
passed through the bones of the roof of the mouth.
993. _Why do hairs grow across the passages of the nostrils?_
Because they form a _defence_ against the admission of dust and
insects, which would otherwise frequently irritate the nervous
structure of the nose.
994. _Why are the nostrils directed downwards?_