Organ

An enclosed Choir Organ frequently houses the independent mutation stops, which are found to answer best in the shape of gedeckt pipes. Mutations commonly used are: nazard or twelfth (24ft.), tierce or seventeenth (IVO, larigot or nineteenth (I lft.), septierne or flat twenty-first (z+ft.) and if it may be termed a mutation, the octavin or twenty-second (ift.). With these or an even fuller muster to hand immense colouristic possibilities lie in front of the organist. Like a chemist in a laboratory he has only to mix one or two mutations with a 4ft. or 2ft. stop or even with another mutation to create new tonal compounds of rare and surprising piquancy. An excellent "orchestral oboe" can be made from this recipe—viole 8ft., nazard 24ft. and tierce lft.

Reeds are neither few nor insignificant on the French Positif, , but in England the Choir is more often than not limited to a clarinet or cor anglais 8ft.

Solo Organ.—The Solo (or Orchestral) Organ differs from the three foregoing sections in one practical respect. Hitherto we have been dealing with units which were designed with the aim of building up a harmonious whole.

It is not perhaps overstating the case to say that the English Solo Organ is considered successful in proportion as it is anom alous in relation to the rest of the instrument. Being largely imitative of orchestral instruments, its stops, both reed and flue, represent extremes of scaling and voicing; and so have a poor blending capacity.

The Orchestral Organ may be regarded as a modern off-shoot of the Solo, which it sometimes includes on the fourth manual.

So many solo stops are intended to resemble orchestral instru ments, so many "orchestral" or imitative stops are distinctive enough to take a solo melody or melodic part, that the two names must largely overlap. Some builders, however, prefer to assign the Solo and Bombarde to a fifth manual, while retaining the fourth for an Orchestral pure and simple. Or, if there are only four manuals all told, the Choir and Orchestral are made to share the third, Solo and Bombarde the fourth.

Among the most prominent features of the Solo-Orchestral section is a pungent viol family. This may be more or less fully developed from the i6ft. contra-viol or violone, through the unison viol d'orchestre or violoncello to a viol mixture of 3 or more ranks, according to the size of the section.

In complete contrast stand the powerful orchestral flutes, which are invariably harmonic and appear at 8ft., 4ft. and 2ft. pitches.

One name for the 4ft. rank is flauto traverso, the 2ft. nearly always being termed piccolo. Of gedeckts a large-scale tibia clausa is at once the most effective and the most vulgar.

Bassoon or fagotto i6ft., clarinet 8ft. (and sometimes i6ft.), orchestral oboe 8ft., orchestral trumpet 8ft., French horn 8ft., English horn Oft. and 8ft., are all imitative reeds which find an appropriate home in this section. Though probably more valuable as a "timbre-creator" than an imitative stop the vox humana passes for "orchestral" and is included here.

As befits its character, the Solo-Orchestral section must be enclosed in its own swell-box and voiced on a fairly heavy wind pressure, so that its stop may tell out clearly.

Echo Organ.

If the principle of senores priores counts for anything, an enclosed Echo Organ ought to occupy the fifth manual, when one is provided: for such is its traditional place. In the churches of the United States Echo Organs are frequently met with, but without a fifth manual in the console. Modern English practice, however, seems inclined to favour the case of a Solo Bombarde section instead of an Echo Organ for this manual, particularly if tubas are absent from the fourth manual. This would consist of heavy-pressure tubas (r) at the foundation pitches, and a chorus mixture of 6 ranks or more, the whole form ing a forte-fortissimo ensemble. A stentorphone 8ft., i.e., a mon strous solo diapason is often included.

Pedal Organ.

The Pedal Organ supplies a general bass to the whole organ, its stops therefore being pitched an octave lower than those of the manuals having the same nomenclature. Thus the "unison" stops are i6ft. instead of 8ft. A pedal double diapason would be 32ft. instead of i6ft. pitch, a pedal fifteenth 4ft. instead of 2ft., a pedal tierce 3-tft. instead of and so on.

A minimum Pedal Organ could consist of gedeckt or bourdon (t6ft. closed wood) and from these the 8ft. and 4ft. pitches could be derived to form three stops in all. After which the Pedal Organ increases pan passu with the numerical growth of the manual stops. Soon one or more open diapasons Oft. become imperative to balance the Great diapasons. Next a double open diapason 32ft. is the proper offset to 5 or 6 ranks of Great mix tures. From which it is but a short step to establish a diapason series from 32ft. to mixtures, thus making the Pedal Organ a complete entity on its own account. Large French Pedal Organs are especially rich in mixtures and mutation ranks, which con tribute of course to reinforce the foundation. Other stops which are required as bass counterparts to manual tones include tibia (f), salicional (echo vd), geigen (vd), contrabass or violone (v), quintaten (g), etc. ; and all these are amenable to extension into higher pitches.