O (It-)- Or.— Violino oflauto, violin or flute.
Obbligato (It.). Lit., "obliged, bound." Indispensable. Gene-rally speaking every independent part is obbligato. The ex-pression organ obbligato, for instance, indicates that the organ is not simply a reinforcement of the other parts, but has some-thing of its own to say. —The obbligato instrumental part fre-quently to be met with in the arias of older operas, oratorios, &c., vied, concerted, with the vocal part. Titles such as these were very common : Aria con violino obbligato, or Jlauto obbligato.
Obbliquo (It.), ObliqUUS (Lat.). Oblique (q.v.).
Ober (Ger.). Above, over, upper.—Oberdominante, the dominant— i.e., the dominant above the tonic; Obernianual, the upper manual; Oberstimme, the highest port; Obertbne, overtones, upper partial tones ; Obenuerk, upper manual.
Obligat (Ger.l. Obligato (It.), Oblige (Fr.). The same as obbligato.
Oblique. The motion of two parts is called oblique when one of them remains stationary and the other moves, (v. Motion.)
Oboe. (') A wood wind instrument with a mouthpiece consisting of a double reed. Its extreme compass extends from b7 or bti to /"'. Music for the oboe is written in the G clef, and written as it sounds. This is the oboe of our orchestras. In military bands are also sometimes to be met with oboes in 1! flat and a soprano oboe in E flat, which are of course transposing in-struments. (2) There are likewise organ stops of the name of oboe, of 8-feet, and more rarely of 4-feet pitch. (3) For other kinds of oboe, oboes now obsolete, see the following articles.*
Oboe basso (It.). This obsolete instrument stood a minor third lower than the ordinary oboe.
Oboe da caccia (It.). A small bassoon a fifth or fourth higher than the ordinary bassoon. It .stood in F or in E flat. Others say that it was like the cor anglais, and that the latter is but an improved oboe da caccia.
Oboe d'amore (It.). This instrument stood, like the oboe basso, a minor third lower than the ordinary oboe, but differed from it and other oboes in the form of its bell and the quality of its tone, which was mellower.
OBOE LUNGO—ONDEGGIANTE.
o83

Oboe lungO (It.). The same as oboe if amort. Oboe piccolo (It.). The ordinary oboe. Oboista (It.). An oboist, an oboe player. Occhiali (It.). The same as Brillcnbasse. Octâvchen (Ger.). v. Ottavina.
Octave. (1) The interval of an eighth. (2) An octave, an organ
slop of 4-feet pitch. Octave flute. A piccolo, a small flute whose pitch is an octave
higher than that of the ordinary flute. Octavflbte (Ger.). (1) An octave flute. (2) An octave, an organ
slop of 4-feet pitch. Octavfolgen (Ger.). Consecutive octaves.
Octaviana, Octavina, Octavine. v. Ottavina. Octavino. v. Ottavino.
Octet. A composition for eight voices or instruments. Octett (Ger.). An octet.
Octobasse (Fr.). A monster double bass twelve feet high, invented
by Vuillaume. It is managed by means of keys and pedals. Octochord. An instrument with eight strings. Octuor (Fr. ). An octet.
Octuplet. A group of notes which divides a bar or part of a liar into eight instead of six equal parts.
Ode. A song. A poem lyrical in matter and dignified in treatment. A musical setting of such a poem.
Odeon (Gk.), Odeum (Lat.). A public building for musical per-formances.
Œuvre (Fr.). A work, a composition.—Chef-d'œuvre, a master-piece. Œuvre posthume, a posthumous work. Offert (Ger.). Open. A term applied to organ pipes.
Gffenbare Octaven, Offenbare Quinten (Ger.). Lit.,
" manifest octaves, manifest fifths." Consecutive octaves and fifths which are not hidden.
Offertoire (Fr.), Offertorio (It.), Offertorium (Lat.). The
offertory or the music sung or played during the offertory, which is the part of the mass between the Credo and Sanctus, when the priest prepares the elements and offers them upon the altar. Oflcleide (It.). Ophicleide.
Obne (Ger.). Without.—Ohne Begleitung, without accompaniment. Ohne Dàmpfer, without the mute, without mutes ; in pianoforte music, without dampers—i.e., with the so-called loud pedal.
Olivettes (Fr.). A dance in use among the Provencals after the olive harvest.
Omnes (Lat.). All. The same as tutti.
Omnitonique (Fr. ). Having all tones.—Cor omnitonique, a chro-matic horn.
Once-accented octave, v. Introduction, p. 5. Ondeggiamento (It.). Undulation, waving. OndePgiante (It.). Undulating, waving.

ONDULATION—OPHICLEIDE.

Ondulation ( Fr. ). Undulation, waving.
Ondulé (Fr.), Undulated, waved.
Ong"arese. v. Ungarese.
Onzième (Fr.). The interval of an eleventh.





Open diapason, v. Diapason and Open stops.
Open notes, (i) On stringed instruments, those notes which are produced without stopping, that is, without placing the ringers on the strings for the purpose of shortening their sounding length and thus changing their pitch. (2) On wind instru-ments, the natural notes, those produced without any artificial or mechanical means (stopping or valves), simply by the manage-ment of the breath, (v. Horn. )
Open pipes. Organ pipes the upper ends of which are open, not closed as those of stopped pipes.
Open stops. Stops—i.e., sets of pipes, consisting oiopenpipes (a.v.).
Oper (Ger. ). Opera.
Opera (It.). A musical drama. This at any rate the opera pre-tends to be ; it is, however, often merely a stage concert with some sort of dramatic action for pretext. The chief constituents of the opera, apart from the overture, are the recitative, aria, chorus, and the various kinds of ensemble—duet, trio, quartet, quintet, sestet, &c.—of which the finale is the most important. The finale is generally of a complex form ; duets, trios, &c, are mostly, and choruses sometimes, modelled on the aria form, or rather forms, {v. Aria, Recitative, and Finale.) Opera came into existence about 1600, and since then has undergone many changes. Its latest reformer was Richard Wagner, who, on the one hand, paid special regard to the dramatic and poetic aspect of the opera, and, on the other hand, abandoned independent, self-contained forms, and to some extent levelled, as it were, recitative and aria. In the following articles some of the various kinds of opera are mentioned.
Opéra bouffe (Fr.). A comic opera, but one of a much lighter character than an opéra comique.
Opera bufia (It. ). A comic opera.
Opéra comique (Fr.). (1) A comic opera. An opera with spoken dialogue, as distinguished from the grand opera, which has no spoken dialogue. (2) Name of the second opera-house in Paris. There operas with spoken dialogues are performed.
Opéra lyrique (Fr.). A lyric opera.
Opera seria (It.). A "serious opera," the counterpart of an opera buffa, just as a tragedy is the counterpart of a comedy.
Operetta (It.), Opérette (Ger.). A short or a light opera, some-times an opera both light and short. Latterly the word has become almost synonymous with opéra bouffe.
Opnicleide. A keyed wind instrument now generally made wholly of brass. The ophicleide in C has a compass from B, to c". This is the most common one, but ophicleides of higher and
OPUS—ORDINARIO.
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lower pitch occur also—alto ophicleides in E flat and F, a bass ophicleide (like the one in C) in _ flat, and contra-bass ophi-cleides in E flat and F.
Opus (Lat. )o A work. Op. is an abbreviation of this word. F01 instance: Op. I, first work.
OpUSCUlum (Lat.). A little work.
Oratorio. An extensive composition for solo voices, chorus, and orchestra, the underlying text of which is usually derived from or based on Scripture. It would be possible to take for an opera and for an oratorio one and the same subject—indeed, it has been done—but it could only be done by treating il differently. In the opera, action must be pre-eminent; in the oratorio, contemplation. The peculiar form of the oratorio is a mixture of the dramatic, lyric, and epic, three elements which of course are differently proportioned in different works, and one or the other of which may at times be entirely absent. If we except the chorus, which assumes supreme importance, there are no distinctive musical forms in the oratorio : it consists, like the opera, of recitatives, arias, duets, trios, quartets, &c, an elaborate chorus taking generally the place of the finale. The style, on the other hand, ought to be distinctive. Chasteness, dignity, end grandeur are the qualities of style which the oratorio first of all demands. Hence the contrapuntal texture of the best works of the kind, and their sublimely massive choral fugues. Like the opera, the oratorio came into existence about 1600, and passed through various stages of development. No wonder, then, if the above-given definition does not exactly fit all stages and every individual instance. This has especially to be remembered in connection with the earliest and some of the latest oratorios.
Orchester (Ger.). Orchestra.
Orchestra. (I) In the ancient Greek theatre, the place between the stage and the audience where the chorus was stationed and its dances performed. (2) In modern theatres, the place between the stage and audience where the band of instrumentalists is placed. (3) The place set apart in a concert-hall for the instrumental band and the chorus. (4) A body of instrumentalists performing at a theatre or in a concert-room. Not every body of instrumentalists is called an orchestra. The expression could not be used in speaking of a military band, or any other kind of brass or wind band. (5) The instruments collectively which constitute a band.
Orchestration. The setting, instrumentation, of music for the body of instrumentalists called an orchestra.
Orchestrion. A barrel-organ which aims at the effects of an instrumental band, the several instruments of which it more 01 less happily imitates.
Ordinario (It.). Ordinary, usual, common.—Tempo ordinario, _ (C)time.





ORGAN.

Organ. A keyboard instrument with a more or less great numbei of pipes which are made to sound by means of compressed ail provided by bellows. The pipes—of which it contains several if not many sets (ranks), several or many pipes to each key —stand on a sound-board above the wind-chest, whither the air is conveyed from the bellows through a wind-trunk. Two obstacles have to be removed before the air in the wind-chest can reach the pipes. Pallets closing grooves have to be pulled down and slides below the mouths of the pipes have to be shifted. Each key is, by a complex mechanism (sticker, roller, tracker, &c.), in communication with a pallet. As soon as a key is pressed down the corresponding pallet gives the air access to a groove, above which are placed all the pipes belonging to the key. Still, no sound is produced, as the air is intercepted by the slides, each of which runs below the mouths of a whole rank of pipes (a complete rank of pipes being equal in number to the keys of the keyboard). Now, by pulling out a stop, one of the slides—which are laths with holes in them—is shifted in such a way as to bring the holes just below the mouths of the pipes. On drawing out one stop you can by playing on the keyboard make one of the ranks of pipes speak; on drawing out two stops, two ranks of pipes ; and so on. Pipes are made of wood and of metal. The most important distinction, however, is that of Jlue-pipcs and reed-pipes. In flue-pipes the wind rushes against a sharp edge, in reed-pipes against a metal tongue. Another important distinction is that of open and stopped pipes; a stopped pipe of the same length as an open pipe being an octave lower in pitch. Stops and pipes are said to be of 8, 4, 2, 16, 32, &c, feet pitch. With an 8-feet stop you get on pressing down a key a sound corresponding to the note indicating that key; with a 4-feet stop a sound an octave higher, with a 2-feet stop a sound two octaves higher, with a 16-feet stop a sound an octave lower, &c. Very small organs have only one keyboard, or manual; very large organs have as many as four or even five. They are respectively called : the great, choir, swell, and solo organ. Moreover, there are pedals—i.e., a key-board for the feet. By couplers several keyboards may be combined, so that in playing on one of them you act also on the other. The different ranks of pipes, or stops, differ in quality of tone, which depends upon the material they are made cf, and especially on their form and scale (relative proportion of length and width). The variety of stops and their names is very great. Here are a few: open diapason, stopped diapason, double diapason, principal, fifteenth, flute, dulciana, gamba, bassoon. Mixture, sesquiáltera, and some others are stops consisting of several ranks of pipes, sounding the fifth, third, &c., of the fundamental note in a higher octave. The organ came into use among the people of Western Europe in the middle ages. The compass of the principal manual keyboards is now usually about
ORGANETTO—OVERTURE.
87

four octaves and a half (from C to/"' or g'"), that of the pedal keyboard about two octaves and a half (from C to /'). The actual compass (the sound-compass) of organs with stops of different pitch, that is of all but the smallest organs, is of course greater than that of their keyboards.
Organetto (It.). A small organ.
Organista (Lat. and It.). An organist.
Organistrum (Lat.). A hurdy-gurdy.
Organo (It.). Organ.—Organopieno, full organ.
Organo portabile (It.). A portable organ.
Organum (Lat.). (1) Aninstrument; an organ. (2) The name of the first attempts at harmonic combination (about 900) that have come down to us. Its most primitive form consisted in sue cessions of fifths and fourths.
Orgel (Ger.). An organ.
Orgelpunkt (Ger.). A pedal-point, pedal-note, or "organ-point."
Orgelregister (Ger.). An organ stop.
Orgue (Fr.). An organ.
Orgue expressif (Fr.). A harmonium.
Ornamenti (It.). Ornaments, grace notes.
Ornatamente (It.). With embellishments, gracefully.
Ornato(It.). Adorned.
Omements (Fr.). Embellishments, grace notes.
Orpheon (Fr.). The name of choral societies of men in France.
Osservanza (It.). Attention, observance.—Con osservanza, with observance of what pertains to a proper rendering.
Ossia (It.). Or.—This word is found where two readings are given and the player or singer may choose the one which suits him best.
Ostinato (It.). Obstinate.—Basso oslinato: (1) aground bass ; (2) a bass that adheres obstinately to one rhythm.
Ottava (It.). An octave.—Ottava alta, the high octave, or an octave higher; ottava bassa, the low octave, or an octave lower.
Ottavina (It.). (1) A small spinet an octave higher in pitch than the largest kind of spinet. (2) A register, found in harpsichords and other keyboard stringed instruments, consisting of a set of strings tuned an octave higher than the other strings, which it reinforces. Sometimes this register could be brought into and out of action by a stop. (3) Ottavina has also been used in the sense of " superoctave."
Ottavino (It.). (1) An octave flute (a.v.). (2) A =mn!I spinet. (v. Ottavina.)
Ottemole (Ger.). Anoctuplet.
Ottetto (It.). An octet.
Ottone (It.). Brass.—Stromento d'ottone, a brass instrument. Ouverture (Fr.). An overture.
Overture. The name of the opening orchestral piece of an opera, oratorio, cantata, or other large vocal work. Formerly this term was sometimes applied to the first number of series of

ieces for one or several instruments, such as Suites and artitas ; now frequently to independent orchestral compositions, the so-called concert-overtures.
The modern overture—in place of which one finds often in operas, oratorios, &c, a prelude or introduction—presents itself generally in one of the following forms :—
(i) In the sonata form, or to be more explicit, in the first-movement form of a sonata. Nearly all concert-overtures and a great number of overtures to vocal works are in this form. (2) In the sonatina form, that is, in the first-movement form of the sonata without the middle division—the development, or working-out section—instead of which a few intervening bars or passages are introduced. (3) In a form not classifiable under any of the generally accepted patterns, and based in part or wholly on motives derived from the work to which it is prefixed. (4) In the form of a pot-pourri of operatic airs.
Of the older overture are especially notable these two species:—
(1) The French, or Lully's, overture, which always begins with a slow, stately movement, followed by a quicker move-ment in the fugal style, and often, but not always, concludes with another slow movement, a modification of the first. (2) The Italian, or Scarlatti's, overture, which consists of one slow and two quick movements, the former being placed between these latter.