[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 requisite lip tension. By means of the pistons the compass of the cornet is thus extended from [graphic] to [graphic].
[Illustration: Real sounds for the cornet in C.
(The minims indicate the practical compass but the extension shown by the crotchets is possible to all good players.)]
The treble clef is used in notation, and in England the music for the cornet is usually written as sounded, but most French and German composers score for it as for a transposing instrument; for example, the music for the B[flat] cornet is written in a key one tone higher than that of the composition.
The _timbre_ of the cornet lies somewhere between that of the horn and the trumpet, having the blaring, penetrating quality of the latter without its brilliant noble sonorousness. The great favour with which the cornet meets is due to the facility with which it speaks, to the little fatigue it causes, and to the simplicity of its mechanism. We must, however, regret from the point of view of art that its success has been so great, and that it has ended in usurping in brass bands the place of the bugles, the tone colour of which is infinitely preferable as a foundation for an ensemble composed entirely of brass instruments. Even the symphonic orchestra has not been secure from its intrusion, and the growing tendency in some orchestras, notably in France, to allow the cornet to supersede the trumpet, to the great detriment of tone colour, is to be deplored. The cornet used in a rich orchestral harmony is of value for completing the chords of trumpets, or to undertake diatonic and chromatic passages which on account of their rapidity cannot easily be fingered by trombones or horns. The technical possibilities of the instrument are very great, almost unrivalled in the brass wind:--notes sustained, crescendo or diminuendo; diatonic and chromatic scale and arpeggio passages; leaps, shakes, and in fact all kinds of musical figures in any key, can be played with great facility on the three-valved cornet. Double tonguing is also practicable, the articulation with the tongue of the syllables _ti-ke_ for double, and of _ti-ke-ti_ for triple time producing a striking staccato effect.