This is the eleventh of a multi-part post. (Please see previous posts below for earlier installments.)
Example 12, Blitheman’s Gloria tibi trinitas II (the second of his six settings of the antiphon in the Mulliner Book) is mostly in two parts with a final section in three parts. It has a simple plainsong in the top part. For plainsong notes 1-15 there is one descant below with 8:1; for plainsong notes 16-26 there is a change of proportion to 6:1; and for several notes (17, 19, 21-26) the descant consists entirely of consonances. At plainsong note 27 a second descant is added that is also 6:1 against the plainsong, i.e. the two descants are 1:1 in relation to each other; they frequently move in parallel 3rds or 6ths (as in Ex. 4b).
As discussed in Part 1 of this blog (Fig. 2), Tudor choristers began their study of descant by singing consonances (3rd, 5th, 6th and octave) above a plainsong. Lionel Power’s treatise ‘contriued vpon the gamme [gamut]’ for teaching children deals only with this stage in their education. Singing descant below plainsong is significantly more difficult to do. The consonances are the same, of course: as Morley explains (Introduction, p. 86), in ‘bass descant’, either you may reckon your cordes [i.e., intervals] from your base vpwardes, or from the plainesong downewarde, which you list. For as it is twentie miles by account from London to ware, so is it twenty from Ware to London’. But as Thomas Campion points out (A new way of making fowre parts in counter-point, London, 1610 [C2r-v]) when a consonance is inverted it can turn into a dissonance (such as a consonant perfect 5th inverting to a dissonant perfect 4th):
Such Cords as stand aboue the Notes of the Base [i.e. plainsong] are easily knowne, but such as in sight are found vnder it, trouble the young beginner; let him therefore know that a third vnder the Base, is a sixt aboue it, and if it be a greater [major] third, it yeelds the lesser [minor] sixt aboue; if the lesser third, the greater sixt. A fourth vnderneath the base is a fift aboue, and a fift vnder the Base is a fourth aboue it.
Figure 3 Intervals and their inversions (M = major; m = minor; P = perfect):
The process of learning bass descant is made much easier by physically playing intervals and their inversions on a keyboard instrument: a perfect 5th played on a keyboard not only fits neatly under the hand, it also looks similar to the lines of a staff turned sideways to the right, and therefore makes ‘sighting’ intervals concrete. Ex. 1 in Part 1 of the blog, Blitheman’s Dignare, which is 3:1, all consonances, could be used as a lesson in how to practice playing only consonances below a plainsong.
(Note: Ex. 12 is recorded up 4th, since the lowest note on the Wingfield organ is F.)