adjacent bones of the face and forehead, and com-
municate freely with them. In each cheek-bone,
for example, is a hollow of this kind, called the
cells of the cheeks, or the caves of Highmore, from
the person who first described them. These cells

are situated in the parts of the cheek-bones which
bulge out at some distance below the inner corners
of the eyes, extending nearly to the upper jaw.
Behind what is commonly called the root of the
nose, and between the inner corners of the
eyes, are
four or more cells, somewhat like a honey-comb,
which open into the upper part of the nostrils, by
many small tubes, placed one above another in a
transverse position. Two other similar cells are
formed in the bone which constitutes the eye-brows,
and communicate with the nostrils, by openings in
the bones. There is also a cell of the same kind
immediately over the roof of the mouth, and others
more inward in the bones of the skull.

All these cells open into the inner part of the nose; the lower and more outward channels of the nostrils having no communication, except with the eyes, in receiving the tears through a pipe on each side drilled in the bone. The surface of the nasal passages, and of course the space over which the sound of the voice travels, is much increased, also, by the spiral turns or folds of several shell-like bones, hollow, and spungy within, convex without,

and every where covered by a membrane similar to that in other parts of the nostrils. In hounds, and other acute-smelling animals, these are more numerous than in man, and are beautifully formed into spirals.

The nasal passages are separated from the mouth by a thick, fleshy, and glandular skin or membrane, which is partly stretched, and partly hangs down at the back part of the mouth. To this curtain is hung a little weight, which may be seen on opening the mouth pretty widely. It seems to be designed to guard the fauces, and make the curtain hang steady.

The whole of the nasal passages, with their cells and communicating hollows, are lined with a delicate skin or membrane-called the Schneiderian membrane, from Schneider, a German, who was the first to describe it accurately. It is a pulpy, soft substance, full of pores and small vessels, with which the nerves of smell are minutely interwoven. It adheres every where firmly to the bone, not being covered so thickly with skin as the mouth and other parts; and the blood-vessels being usually full of blood, and much exposed, it is very liable to be affected with cold, and to become swelled and inflamed.

M. Magendie is of opinion, that whenever the sound of the voice traverses those nasal passages,

the tone will be disagreeable, or, as it is commonly called, nasal and accordingly he says, that persons who think that the nasal cavities can augment the intensity of vocal sound, by resounding through them, deceive themselves, as this cavity can only produce the reverse effect; for whenever from any cause the sound is introduced into them, the voice becomes dull and nasal. Blumenbach seems to be of the same opinion; but, even at the hazard of opposing such high authorities, we beg to give our reasons for being of a contrary opinion. A simple experiment, we think, will settle the difference. If you attempt to speak while you stop your nostrils, the sound of the voice will have more of the character of what is called nasal, than if the nostrils were free; which proves, we think, beyond a doubt, that a portion of the sound of the voice usually traverses the nasal passages, and passes out at the nostrils. The clearer therefore these passages are, the more distinct and free will be the sound of the voice. When they are obstructed or closed by a cold, therefore, or from the bad habit of taking snuff, the clear tones of the voice are always impaired and deteriorated, as we shall see at greater length as we proceed.

THE MOUTH.

The arched form of the roof of the mouth is evidently adapted for increasing the sound of the voice, and accordingly we find, that when it is wanting, as it sometimes is at birth, the voice and speech are greatly injured. The volume, positions, and movements of the tongue, are no less worthy of our observation; for though it is chiefly useful in articulating, it has also a powerful influence on the sound, by contracting or enlarging the cavity of the mouth.

The teeth, from their very hard and sonorous substance, are also well adapted for increasing the volume of the sound; and nothing, therefore, tends more to hurt the voice than the loss of the teeth. In old age, when the teeth are all gone, and the jaw projects, the voice is by this means, as well as by changes in the larynx and vocal chords, very much enfeebled.

II.

MECHANISM OF THE VOICE.

SUCH different views have been taken of the mechanism of the human voice, that it is by no means easy to reconcile them. Galen, the famous Greek physician, compared it to a flute, supposing it to be wholly of the nature of a wind instrument; and in modern times Dodart has advocated the same opinion. Ferrein and others, on the contrary, have compared it to a violin, the vocal chords being in this instance supposed to perform the office of strings. Kratzenstein thought it was like a drum with its head divided; and Blumenbach compares it to an Eolian harp, -a stringed instrument played upon by the wind. M. Magendie refers us to those instruments whose sound is produced by a reed, such as the hautboy, pipe, and clarionet. It will be necessary, however, for M. Magendie's comparison, ingenious as it is, to observe that the various tones of the voice are produced, not by stopping the holes at different distances, as in those reed instruments, but in varying the width of the windpipe at its orifice or outgoing, where the prin