played,' the fact being that the bass part is an octave too low. In consequence of this misconception, no two scales as given in the ordinary instruction books agree with one another; many beginning at the 4-foot C, which stands second in the scale diagram given above. This is partially owing to the fact that the extreme low tones are difficult, if not impossible to produce, except with a larger mouthpiece. Indeed, 16-foot C can only be feebly touched with a trombone mouthpiece and by an experienced trombone player. The scale given above agrees with the harmonic series common to all modes of eliciting sound, and has therefore been preferred for illustration. The Horn is invariably written for in the G or treble clef (with the exception of the three or four lowest sounds described above), and in the key of C; the difference of pitch necessary for orchestral tonality being provided by the various crooks, of which eleven are used, supplemented by two intermediate; one of which lowers the pitch of any crook approximately a semitone, the other a whole tone. The whole diatonic scale is thus accessible, and even lower pitches than C are occasionally needed, as in the 'Stabat Mater' of Rossini, where a horn in A♭ basso is introduced. The upper C crook is rarely used, and the series commonly terminates with B♭ basso. In his 2nd Symphony, Brahms uses 2 horns in B♮ basso, and 2 in C basso. The following table shows the relation between the written notes and the actual sounds produced in the various Horns:—
| Written notes. | C Horn. | D Horn. |
 |
 |
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| E♭ Horn. | E Horn. | F Horn. |
 |
 |
 |
| G Horn. | A♭ Horn. | A Horn. |
 |
 |
 |
| B♭ alto Horn. | B♭ basso Horn. | B♮ bass Horn. |
 |
 |
 |
It will thus be seen that although the written symbol of the sound remains unchanged, the actual sounds produced, and the embouchure required for producing them, vary over a range of more than an octave. This constitutes the chief difficulty of the instrument; for as the various harmonics differ only in the altered tension of the lip-muscles, what is required to produce a high note on a low crook is clearly insufficient for one far lower on the more acute. It is thus often impossible to ascertain, without actual trial, which particular individual of the series may be first struck; the sound for instance which is fundamental on the B♭ alto being the first octave harmonic on the B♭ basso. It is always advisable in writing for an instrument singularly tender and treacherous, to give the player, in case of change, some opportunity of making this adjustment of the lip unperceived, and under the cover of more forcible instrumentation. This precaution is the more needful as the brass tubing of the Horn is very susceptible to changes of temperature, and a cold crook put on suddenly is in consequence liable to commence too flat.
The Horn is seldom played singly in the orchestra. A pair at least, and four, or two pairs, are most commonly employed. The Third is in the latter case regarded as a ripieno first, and the Second and Fourth as being correlative to one another.
Every great composer since Handel has written freely for the Horn. A characteristic specimen of this master occurs in his Allegro and Pensieroso, where the bass song 'Mirth, admit me of thy crew,' is embellished by a brilliant arpeggio accompaniment rising to the top C. This solo, though preserved among the orchestral parts, and occasionally played, is not to be found in the score of the German Handel Society, nor in Arnold's edition of the work; so that, though traditionally referred to Handel, it may be a subsequent addition. [App. p.679 "omit the sentence beginning This solo, though preserved, etc."]
Mozart, even where his score is otherwise limited, hardly ever dispenses with two horns. For these he writes with the most perfect tact and judgment; seldom introducing hand notes, except when their peculiar effect is required. Instances of this can easily be found in any of his symphonies, overtures, or operas. He has moreover written three concertos for orchestra with Horn obbligato, and a large quantity of concerted music such as that named under Clarinet for two horns and the reed instruments. All his compositions are eminently fitted for the hand-horn, of which he had thoroughly studied the capacities.
Beethoven has been especially lavish, though singularly cruel and exacting, in the use of the Horn, for besides the Sonata in F for Horn and Piano, the Sestet, for String quartet and two Horns obbligato which is so difficult as to be never played, and the Septet, which contains a trying passage in triplets for E♭ horn,—
he constantly gives it a prominent place in all his works. The most noticeable of these are the Second Horn solo in the overture to Fidelio, in E, which incidentally demonstrates the error in notation adverted to above.
