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.