ng-fork Tests._--To differentiate between deafness due to a
lesion in the sound-conducting apparatus and that due to labyrinthine
causes, it is necessary to enter into a little more detail. The tone
produced by a vibrating tuning-fork is conducted to the nerve
terminations in the labyrinth both through the air column in the
external meatus (air-conduction), and through the cranial bones
(bone-conduction). When, in a deaf ear, the vibrations of a
tuning-fork placed in contact with the mastoid process are heard
better than when the fork is held opposite the meatus, the lesion is
in the sound-conducting apparatus. When, on the other hand, the
vibrations are heard better by air-conduction, the lesion is in the
sound-perceiving apparatus. In addition to these facts, we find also
that in obstructive deafness low tones tend to be lost first, while in
nerve deafness the higher notes are the first to go. This may be
investigated by tuning-forks of different pitch or with the aid of a
Galton's whistle. Again, in middle-ear deafness, hearing may be better
in a noisy place, and be improved by inflation of the tympanum; while
in labyrinthine deafness, hearing may be better in a quiet room, and
be rendered worse by inflation.

#Inspection of the Ear.#--This should be carried out by the aid of
reflected light, the ear to be examined being turned away from the
window, lamp, or other source of light that may be employed. A small
ear reflector, either held in the hand or attached to a forehead band,
and a set of aural specula are required. Before introducing the
speculum, the outer ear and adjacent parts should be examined, and the
presence of redness, swelling, sinuses or cicatrices over the mastoid,
displacement of the auricle, or any inflammatory condition of the
outer ear observed. To inspect the tympanic membrane, a medium-sized
speculum held between the thumb and index finger is insinuated into
the cartilaginous meatus, the auricle being at the same time pulled
upwards and backwards by the middle and ring fingers, so as to
straighten the canal. The tympanic membrane is then sought for and its
appearance noted.

The _normal membrane_ is concave as a whole on its meatal aspect; it
occupies a doubly oblique plane, being so placed that its superior and
posterior parts are nearer the eye of the examiner than the anterior
and inferior parts. While varying to some extent in colour, polish,
and transparency, it presents a bluish-grey app