a gradual increase in diameter to the bell.  The slide used for the trumpet appears for four centuries, and probably longer, in the well known construction of the trombone.  In this instrument it consists of two cylindrical tubes parallel with each other, upon which two other tubes communicating by a pipe at their lower ends curved in a half circle glide without loss of air.  The mouthpiece is fitted to an upper end, and a bell to a lower end of the slide.  When the slide is closed, the instrument is at its highest pitch, and as the column of air is lengthened by drawing the slide out, the pitch is lowered.  By this contrivance a complete chromatic scale can be obtained, and as the determination of the notes it produces is by ear, we have in it the only wind instrument that can compare in accuracy with stringed instruments.  The player holds a cross bar between the two lengths of the instrument, which enables him to lengthen or shorten the slide at pleasure, and in the bass trombone, as the stretch would be too great for the length of a man’s arm, a jointed handle is attached to the cross bar.  The player has seven positions, each a semitone apart for elongation, and each note has its own system of harmonics, but in practice he only occasionally goes beyond the fifth.  The present trombones are the alto in E flat descending to A in the seventh position; the tenor in B flat descending to E; the bass in F descending to B, and a higher bass in G descending to C sharp.  Wagner, who has made several important innovations in writing for bass brass instruments, requires an octave bass trombone in B flat; an octave lower than the tenor one, in the “Nibelungen.”  The fundamental tones of the trombone are called “pedal” notes.  They are difficult to get and less valuable than harmonics because, in all wind instruments, notes produced by overblowing are richer than the fundamental notes in tone quality.  Valve trombones do not, however, find favor, the defects of intonation being more prominent than in shorter instruments.  But playing with wide bore tubas and their kindred is not advantageous to this noble instrument.

The serpent has been already mentioned as the bass of the obsolete zinken or wooden cornets, straight or curved, with cupped mouthpiece.  It gained its serpentine form from the facility given thereby to the player to cover the six holes with his fingers.  In course of time keys were added to it, and when changed into a bassoon shape its name changed to the Russian bass horn or basson Russe.  A Parisian instrument maker, Halary, in 1817, made this a complete instrument, after the manner of the keyed bugle of Halliday, and producing it in brass called it the ophicleide, from two Greek words meaning serpent and keys—­keyed serpent—­although it was more like a keyed bass bugle.  The wooden serpent has gone out of use in military bands within recollection, the ophicleide from orchestras only recently.  It has been superseded by the development of the valved