The reader will find that in scores the clarinet part is usually written in some other key than that of the composition. This is because three kinds of clarinet are employed, clarinets in A, B flat, and C. A clarinet in B flat means one whose pitch is a whole tone below the standard, so that when one plays the scale of C natural on it he gets the sounds of the scale of B flat, just as he would from a piano tuned a whole tone too low. A clarinet in A is a tone and a half below pitch in the scale of C. One in C produces the scale of C when played in C. The reason for using different kinds of clarinets is that it is difficult to play the instrument in remote keys. By using an A clarinet for keys having sharps and a B flat clarinet for keys having flats, much of the difficulty is obviated. A clarinet in A is producing the sounds of the key of three sharps when it is playing in C. To get the sounds of the key of six sharps, it is necessary only to write for the A clarinet in three sharps. Similarly, to get the sounds of the key of five flats one needs only to write in three flats for a clarinet in B flat. The kind of clarinet to be used is designated in the score. Instruments treated in this manner are called transposing instruments. ([See Chapter V].)
THE BASS CLARINET
The bass clarinet is a clarinet whose compass extends an octave below that of the B flat clarinet. It is a long instrument with a curved bell at the lower end, so that it looks like an old-fashioned Dutch pipe. Bass clarinets in B flat and A are employed, and the music is usually written on the treble clef, thus transposing an octave below. Wagner uses the bass clef, which is more convenient for the student of his scores than for the performer. The tone of the lower register of the bass clarinet is sonorous and rich, and affords a fine bass for wood-wind passages.
As a solo instrument the bass clarinet is admirable in its dignity. The instrument is used singly, not in pairs. As a fine example of the effect of the bass clarinet, the music of Elizabeth’s final exit in Act III. of “Tannhäuser” may be commended.
III
Wind-Instruments of Brass
THE HORN
The brass choir is composed of horns, trumpets, and trombones, with the addition in most modern scores of a contra-bass tuba. Wagner has used also bass trumpets and tenor tubas to enrich the color of this part of his orchestra. The horn, or French horn, as it is often called, is the old hunting horn adapted to orchestral purposes. It is an extremely valuable instrument, because it has a most noble and expressive tone, which makes it very interesting as a solo voice, and equally because it blends admirably with either strings or wood, as well as with brass. In the older compositions the reader will find that two horns were used, but it is customary with modern composers to employ four, thus making a full four-part harmony possible. Wagner generally doubles his horn parts, requiring eight instruments.
It was impossible in earlier times to play in all keys on any one horn, and so horns in various keys had to be used. The reader will find that many scores call for horns in D, in E flat, in B flat, etc. Players now use almost exclusively the horn in F, with valves, upon which it is possible to play in all keys. It is customary with many composers, however, to write horn parts in various keys, and the players have to transpose them. As no opera is more familiar than “Faust,” the reader may readily identify the horn as a solo instrument in the first act when Mephistopheles shows Faust the vision of Marguerite.