he superintendence of Albrecht Durer.

(b) CORNET A PISTONS, CORNET, CORNOPAEAN (Fr. _cornet a pistons_; Ger.
_Cornett_; Ital. _cornetto_), are the names of a modern brass wind
instrument of the same pitch as the trumpet. Being a transformation of
the old post-horn, the cornet should have a conical bore of wide
diameter in proportion to the length of tube, but in practice usually
only a small portion of the tube is conical, i.e. from the mouthpiece to
the slide of the first valve and from the slide of the third valve to
the bell. The tube of the cornet is doubled round upon itself. The
cup-shaped mouthpiece is larger than that of the trumpet; the shape of
the cup in conjunction with the length of the tube and the proportions
of the bore determines the timbre of the instrument. The outline of the
bottom of the cup, where it communicates with the bore, is of the
greatest importance.[17] If, as in the trumpet, it presents angles
against which the column of air breaks, it produces a brilliant tone
quality. In the cornet mouthpiece there are no angles at the bottom of
the cup, which curves into the bore; hence the cornet's loose, coarse
quality of tone. The sound is produced by stretching the lips across the
mouthpiece, and making them act as double reeds, set in vibration by the
breath. There are no fixed notes on the cornet as in instruments with
lateral holes, or with keys; the musical scale is obtained by means of
the power the performer possesses--once he has learned how to use it--of
producing the notes of the harmonic series by overblowing, i.e. by
varying the tension of the lips and the pressure of breath. In the
cornet this series is short, comprising only the harmonics from the 2nd
to the 8th:

[Illustration: Harmonic series of the B[flat] cornet--the 7th is
slightly flat, a defect which the performer corrects, if he uses the
note at all.]

The intermediate notes completing the chromatic scale are obtained by
means of three pistons which, on being depressed, open valves leading
into supplementary wind-ways, which lengthen the original tube. The
pitch of the instrument is thus lowered respectively one tone, half a
tone, and one tone and a half. The action of the piston temporarily
changes the key of the instrument and with it the notes of the harmonic
series. Before a performer, therefore, can play a note he must know in
which harmonic series it is best obtained and use the proper piston in
conjunction with the r