[31.]—Previous to 1660, each eighth or shorter note had a separate hook or hooks. But at the time of the Restoration, John Playford substituted a connecting horizontal line for the separate hooks of two or more eighths belonging to the same division of the measure. The device was copied by the Dutch, French, and Germans. The Italians did not adopt it till later. Thus, Marcello's Psalms, published in Venice as late as 1724–27, have separate hooks. (In an edition in the writer's possession, published in 1757, united hooks are used, but this is probably rather due to the venue than to the later date.)
[32.]—Hooks in instrumental music must be united in strict accordance with the laws of rhythm (see “Notation of Rhythm,” pars. [8]–13). Thus, four eighth notes must not have the same hook in Compound Time: they must be grouped as three and one, or one and three, or two and two, according to the position they occupy in the beat they belong to. In three-four time, six eighth notes may have one hook, but in six-eight time they should preferably have separate hooks of three eighth notes each. Broadly speaking, the notes forming a single beat of the measure should be united in one hook, but very commonly two beats have one hook between them, especially in four-four time.
In the case of sixteenths and shorter notes, the outermost hook often shows the half-measure, and the inner hook or hooks the sub-division into beats (see [Fig. 21]).
Fig. 21.
[33.]—So closely should the hooks follow the rhythm, that where a phrase crosses the measure beginning at the end of one measure, and ending at the beginning of the next, the hook crosses the bar-line too, uniting notes in different measures (see a, [Fig. 22]). Notes may have the same hook though separated by a rest (see b, [Fig. 22]).
[34.]—The hook to a group of notes which ascends or descends may either slant in the direction taken by the notes, or may be straight (see c, [Fig. 22]). In the writer's opinion slanted hooks are preferable as being a better guide to the eye. In manuscript music, when hooks have to be drawn within the stave, and not above or below it, they should invariably be slanted when this is possible; otherwise they are very apt to coincide with the stave-lines, and fail of distinctness. A common fault is in not making them thick enough. Notes are sometimes “hooked” in accordance, not with the rhythm, but with the hand which is to play them (see d, [Fig. 22]). This is necessitated by the usage with regard to stems in such cases [see “Stems,” [par. 22], exception (2)].