Everybody knows that it is not in the band for musical purposes. It is not a musical instrument. The man who could extract music from a trombone could get grapes out of a coal-mine.
No, its raison d'être is mostly critical and punitive. It is there to see that the orchestra does its job and to put the fear of a hectic hereafter into the man who is out of step with his fellow-conspirators.
The uninformed have a vague idea that the conductor should do that with his little stick. But I put it to you, what use would a little stick be against a man like the big drum? A meat-axe would have some point, but the difficulties of conducting with a meat-axe will be obvious to even the least musical.
When the French horn, in the throes of a liver attack, sees supplementary spots on the score and plays them with abandon, or when the clarionet (or clarinet), having inadvertently sucked down a fly which in an adventurous mood has strolled into one of those little holes in the instrument, coughs himself half out of his evening clothes, does the conductor forsake his air of austerity and use language unbefitting a solemn occasion? Does he pick up his music-stand and hurl it at the offender? He does not. It would be a breach of etiquette.
He simply signals to the trombone, who promptly turns the exit part of his instrument on the culprit and gives a bray that makes the unfortunate man's shirt-front crumple up like a concertina. That is discipline.
Then again the trombone is employed as a sort of brake when in a moment of excitement the rest of the orchestra has a tendency to overdo things.
For example, all will remember the throbbing moment at the end of the drama, where the hero and heroine, murmuring "At last!" fall into each other's arms and move slowly off the stage whilst the band starts up Mendelssohn's or Glückstein's "Wedding March." The effect on an orchestra is immediate and immense. Somewhere behind each of these stiff shirt-fronts beats a heart that thrills at every suggestion of romance. It is well known that, when at intervals during a performance they retire through the man-hole under the stage, it is to imbibe another chapter of Ethel M. Dell or of "Harried Hannah, the Bloomsbury Bride." And so the lingering embrace of the lovers sets them tingling and they tackle the "Wedding March" at the double. The clarionet (or clarinet) wipes the tears from his eyes and puts a sob in his rendering; the cornet unswallows his mouthpiece and, getting his under-jaw well jutted out, decides to put a jerk in it; the piccolo pickles with furious enthusiasm; the 'cello puts his instrument in top-gear with his left hand and saws away violently with the other; the triangle, who has fallen perhaps into a Euclidian dream, sits up and gets a move on; the stevedore—no, no, that is the next chapter—the oboe, the French horn, the kettledrum, the euphonium, the proscenium, the timbrel, the hautboy, the sackbut-and-ashes—all get a grip of the ground with both feet and let her go.
They try to depict golden lands of radiant sunshine, where beautiful couples stroll hand-in-hand for ever and the voice of the turtle replaces that of the raucous vendor of the racing edition.
If they were allowed to have their way the effect on the unmarried portion of the audience would be to send them rushing out of the theatres and dragging registrars out of a sick-bed in order to perform the marriage ceremony there and then.
But the trombone introduces the hard practical note, the necessary corrective. His monotonous grunt is used to remind the audience of marriage as it is lived in real life, of the girl at breakfast in unmarcelled hair, of the man dropping cigarette-ash on the best carpet, of double income-tax, of her family, of his, of her bills for frocks, of his wandering off to golf or the club, and a host of other incidentals.