at significance of resonance is also
beginning to be recognized, the mystery disappears. The same may be
said of the other sinuses--_ethmoidal_, _sphenoidal_, and _maxillary_,
and their interconnection.

[Footnote 2: Dr. Fillebrown's paper, _A Study of the Relation of the
Frontal Sinus to the Antrum_, was read before the American Dental
Association, at Saratoga, August 5, 1895. His investigation showed
that the funnel-shaped passage known as the _infundibulum_ extends
from the _frontal sinus_ directly into the antrum or _maxillary
sinus_. This was afterwards confirmed by Dr. W.H. Cryer and others.]

INFLUENCE OF THE RESONANCE CAVITIES ON THE PITCH OF THE TONE

In instruments changes in the length and form of the resonance
chambers affect the pitch as well as the quality of the tone. This is
demonstrated in the trombone, French horn, and other wind instruments.
The lengthening of the tube of the trombone lowers the pitch of the
tone, and the projection of the hand of the performer into the bell of
the French horn has the effect of raising the pitch of the sound. If
the variation in length or form is only slight, the result is sharp or
flat, and the instrument is out of tune. In the human instrument all
the organs act together as a unit; so the fact that the cavities alone
may affect the pitch is practically of no great significance.

THE TONGUE

The tongue and the lips are the articulating organs, and the former
has an important part to play in altering through its movements the
shape of the mouth cavity.

The tip of the tongue should habitually rest against the under front
teeth. The tip of the tongue, however, must frequently touch the roof
of the mouth near the upper front teeth, as when pronouncing the
consonants _c_, _d_, _g_ or _j_, _l_, _n_, _s_, and _t_. The back part
of the tongue must rise a little to close against the soft palate when
pronouncing _g_ hard, and _k_, and hard _c_, _q_, and _x_. The soft
palate comes down so far to meet the tongue that the elevation of the
latter need be but very slight.

When speaking, the demand is not so imperative, but when singing, the
body of the tongue should lie as flat as possible, so as to enlarge
the mouth, especially when giving the vowel sounds.

If the tongue is sometimes disposed to be unruly, it is the result of
rigidity or misplaced effort in the surrounding parts. This tendency
will only be aggravated by artificial restraint of any kind. The true
w