is in accordance with a rule which is insisted upon by all the best authorities, at least so far as regards the works of great masters, namely, that all graces must fall within the value of their principal note. Türk (Clavierschule) mentions with disapproval the custom of playing it before the beat, and therefore within the time of the preceding note, which method of rendering he describes as 'in the French style,' though it does not appear to have been universal among French musicians, for Boyvin, an eminent French organist, in his 'Premier Livre d'Orgue' (1700), explicitly directs that the Vorschlag shall be struck exactly with the bass.
The Vorschlag in its ordinary form, consisting of a single note one degree above or below the principal note, is of two kinds, long and short. The long Vorschlag, generally known by its Italian name of Appoggiatura, has a definite proportional value, which varies with the length of the principal note, being one-half of a simple note (Ex. 4), two-thirds of a dotted note (Ex. 5), or the whole value of the principal note whenever the latter is tied to another of the same name (Ex. 6). The written length of the Vorschlag, as may be seen from the examples, bears no exact relation to its actual length in performance, though it is customary in the case of the Vorschlag to a simple note to write it of its precise value, as in Ex. 4.
The short Vorschlag, also called unveränderlich (unchangeable) because its value does not vary with that of the principal note, is made as short as possible, and the accent is thrown on the principal note. Like the Appoggiatura, it is written as a small note, usually a quaver (a difference which produces no corresponding diversity in the rendering), and in order to distinguish it from the long Vorschlag it became customary about the middle of the last century to draw a small stroke obliquely across the hook of the note, thus 
. This sign, though highly practical and valuable, has unfortunately been so irregularly and unsystematically employed by composers, and so frequently abused by engravers and printers, that it is at present unsafe to trust to the appearance of the Vorschlag as a guide to its length, which has rather to be governed by considerations of musical effect. This is especially the case with modern editions of classical compositions, both instrumental and vocal, in which it is quite usual to meet with the cross stroke in cases where the long Appoggiatura is imperatively demanded by good taste. For a fuller description of both long and short Vorschlag see Appoggiatura.
VORSPIEL. (Germ.), a Prelude—a piece played before something else, as a piece played after is called a Nachspiel or Postlude. In the sense of an introduction or first movement to a fugue the terms Prelude and Vorspiel have been already examined. [See vol. iii. p. 28.] Bach's Choral- Vorspiele have not however been touched upon. There are organ pieces apparently intended as an introduction to the singing of the hymn in which the chorale is taken as the basis of the piece, the treatment being either by florid and imitative accompaniments to the air in the treble, or in some inner part, in canon or otherwise, or in the bass, or as a fughetta, or in any other way which occurred to the genius and knowledge of this mighty master. Peters's Thematic-Catalogue of Bach's works contains 126 of such Vorspiele, besides 32 'Choral- variationen' on 4 Chorales.
VOX HUMANA, VOIX HUMAINE. An organ stop of 8-feet tone and of the reed family, but with very short capped pipes, which therefore reinforce only the overtones of the fundamental. The pipe for the CC note, which would in the case of an ordinary reed-stop be nearly 8 feet in length, is here often only 13 inches. The pipes vary little in length, and there are perceptible breaks in the timbre. As its name implies, the stop is supposed to resemble the human voice. Burney (Tour through Germany, vol. ii. p. 303), speaking of the specimen in the Haarlem organ, says, 'It does not at all resemble a human voice, though a very good stop of the kind: but the world is very apt to be imposed upon by names; the instant a common hearer is told that an organist is playing upon a stop which resembles the human voice, he supposes it to be very fine, and never enquires into the propriety of the name or the exactness of the imitation. However, I must confess, that of all the stops I have yet heard which have been honoured by the appellation of Vox humana, no one, in the treble part, has ever yet reminded me of anything human, so much as of the cracked voice of an old woman of ninety, or, in the lower parts, of Punch singing through a comb.' This more than century-old description is by no means out of date. In acoustically favourable buildings, and when only just audible, the stop has sometimes a weird effect which is not unimpressive, but distinctness is quite fatal. The Vox humana should be placed in a box of its own inside the swell box. It is nearly always used with the tremulant. Opinions differ as to its capacity for combining pleasantly with other registers, and this depends upon the kind of stop. There are instances where it gives a piquant quality to other light stops. Its voicing is very delicate and soon gets out of order.
