Page:Encyclopædia Britannica, Ninth Edition, v. 17.djvu/897

ORGAN 831 stop was voiced as a rule on from 3^- to 4 inches of wind, not quite twice the pressure used in England. The French diapason is a modern variety. It may be described as presenting rather the characteristics of a loud gamba than of a diapason. In other words, the tone tends towards a certain quality which may be described as " tinny " or metallic, or as approaching to that of a string instrument of rather coarse character. Some modern English builders appear to aim at the same model, and not without success. The tone of a diapason must be strong enough to assert itself. It is the foundation of the whole organ tone. It is the voicer s business to satisfy this condition in con junction with the requirement that the tone shall be full and of agreeable quality. The 8 spitzflote may be regarded as a variety of open diapason. The pipes taper slightly towards the top, and the quality is slightly stringy. This stop was much used at one time in place of a second open diapason. But it appears better that, where two open diapasons are desir able, they should both be of full diapason quality, though possibly of different strengths and dimensions. The ad mixture of stringy qualities of tone with the diapasons is always to be deprecated. The 8 gamba was originally an imitation of the viola da gamba, a sort of violoncello. When made of a light quality of tone it is a pleasing stop ; but its use in the great organ instead of a second open diapason is greatly to be deprecated for the reasons just stated. It is frequently found that, where a gamba is provided on the great organ, it is necessary to remove it from the compositions (mechanical arrangements for pulling out the stop-handles in different combinations), as the tone does not blend. The 8 hohlflote is an open flute, usually of wood, and of small scale. If made to a moderate scale and fully voiced it possesses a full pleasant tone, which is a useful support to the foundation tone of the great organ. The 8 clarabella differs from the hohlflote in being usually of rather large scale, and having the open pipes only in the treble. In old organs a separate bass was generally provided ; now it is more usual to supply the stop with a stopped bass. The dulciana and keraulophon, though sometimes found on the great organ, are regarded as more appropriately placed elsewhere. Great The 4-foot stops of the great organ comprise the 4 prin- organ cipal and the 4 flute. The 4 principal is the octave of the 4 leet. O p en diapason, generally of somewhat reduced scale and light but bright quality of tone. The use of the word " principal " in connexion with this stop is purely English, and is said to be connected with the use made of it as the standard of tuning for the whole organ. The Germans and French both designate this stop as " octave." Of the 4 flute there are several varieties, open, stopped, wood, metal, and harmonic. The harmonic flute has open metal pipes of double the conventional length, which speak their octave. This is determined partly by the voicing, partly by making a small hole about the middle of the length, which determines the motion as that of the two separate lengths between which the hole lies. Harmonic flutes have a sweet but full and powerful tone. Other flutes are generally rather light, except the waldflote, which is a powerful stop of a somewhat hooting quality. The great organ flute is frequently used to give bril liancy to light combinations. Thus it may be used with the stopped diapason alone, or with the 16 bourdon alone, or with any of these and either or both of the open dia pasons. Where the diapasons are scarcely strong enough to assert themselves in accompaniment, it is a very common practice to put the 4 flute into the diapason composition. If any such use is made of the flute it is desirable that it should not be too strong ; bat its habitual use to give point to the diapasons is in every way to be deprecated. If the diapasons are not strong enough, let them be altered ; but that the diapasons of any organ should never be heard without the accompaniment of a 4 flute is a barbarism. The ordinary use of the 4-foot stops is to add a degree of loudness to the diapasons. This is accompanied with a certain measure of keenness, which may become disagree able if the 4-foot tone is disproportionately strong. The ordinary practice is to use the 4-foot tone very freely. The 2 twelfth stop sounds fiddle g on the C key. It Great is composed of diapason pipes, rather small and gently or s an voiced. Its use is said to be to thicken the tone, which j* s of it certainly does. But how far the particular effect pro- pjf ch> duced is desirable is another question. It is generally necessary that this stop should be accompanied by the fifteenth or other octave sounding stop of higher pitch. But in some cases the twelfth can be used with notes of lower pitch only. One such combination is twelfth, full-toned 8-foot harmonic flute, soft reed in 16-foot pitch. This combination is sometimes used in single notes for solo purposes. The sound of the twelfth appears to be masked or absorbed by the volume of tone of lower pitch. These combinations require careful handling, as the effect of the twelfth is offensive if it remains distinctly perceptible. The 2 fifteenth, or superoctave, of the great organ con sists of diapason pipes sounding notes two octaves above the normal pitch of the keys. The 2 piccolo is a fluty stop of less power, having the same pitch. The 2-foot tone is commonly used as giving a degree of loudness to the great organ beyond that obtainable with the 4-foot tone. The modern great organ fifteenth is generally a very powerful stop, and requires great caution in its use in organs of moderate size, or in limited spaces. The old English high pitched stops had little power, and their brilliancy was capable of pleasing without offence. The modern great organ up to fifteenth can only be heard with comfort in very large spaces. Under such suitable circumstances the fifteenth is capable of giving to the whole tone a ringing or silvery character, Avhich lends itself specially to contrast with the tone of reeds. This peculiar keen tone, however, requires for its full develop ment the mixtures. Mixture, sesquialtera, furniture, cymbal, scharf, cornet, are various names applied to a description of stop which possesses several ranks, or several pipes to each note. The pipes of each note sound a chord, which is generally com posed of concordant notes of the harmonic series whose fundamental is the proper note of the key. Modern mix tures generally consist of fifths and octaves. Their com position is not the same throughout the whole range of the keyboard. A three-rank mixture may consist of the following (the numbers signify intervals, reckoned along the scale) C c (tenor) 15 19 22 cgtotop 8 12 15. For a somewhat larger full mixture this may be modi fied as follows 15 19 22 . 8 12 15. C c (middle) c fi to top 1 A sharp mixture suitable for a large instrument may be as follows Five Ranks. C c 15 19 22 26 29 c g _/" 8 12 15 19 22 ( f c " i 8 12 15 19 c " to top 15 8 12 15. The last two compositions are given by Hopkins in his great treatise on the organ.