French Baroque Ornamentation Guide: How to Play Boismortier’s Two Trill Symbols

(from Boismortier's Op. 35, left: Bourée en Rondeau in B minor, right: Rondeau "Les Charites" in E minor

One ornamentation question I get asked every now and then is about these two symbols in Boismortier's music: the plus (+) and the squiggle. They both indicate a trill, but why the two different symbols?

I used to answer that pluses in Boismortier tend to be found on longer note values, while squiggles on shorter ones. Whether the note value is considered as long or short is relative to the meter of the music. This generally indicates that pluses are for longer trills and squiggles are for shorter, quicker trills.

However, this passage from his B minor Suite Op. 35 struck a bell for me and I have now a more in-depth answer. You see both signs on the same half-note value. What does Boismortier want to tell us in this case then??

After some thought, I'd define the difference more clearly as having to do with the IMPORTANCE of the trill and the CHARACTER of the appoggiatura. In both cases we'd ALWAYS start from the note above. As far as I've seen, pluses are found at places where there's a harmonic significance, perhaps a cadence or a dissonance. Places where Boismortier probably wants us to do a more PRONOUNCED appoggiatura. Slightly longer, CLEARLY AUDIBLE, LEANING into the dissonance and perhaps yearning or sighing in expression. Squiggles are thus more DECORATIVE and while they can still carry meaning in terms of affect and expression, the appoggiatura should be shorter, sometimes to the point that it's hardly audible depending on speed and the notational value.

In the case of this B minor Bourée (above left), the (+) is thus found on the cadential trill (more harmonic significance), and the squiggle is on the downbeat before. Boismortier wants us to differentiate these two trills so that we don't end up playing them the same way. Both are ornamental but carry different meanings and have separate flavors. Because baroque music is all about CONTRASTS, DETAILS, LIGHT AND SHADOW. Balance something light with something more weighted, have something more passing followed by something more emphasized. One is more electrifying and then it stretches out a bit. Try it this way and then compare it with playing both half notes with equal-sounding trills - which one sounds more interesting? Which one glues your feet to the ground as opposed to taking a joyful leap?

Take another look at the Rondeau "Les Charites" (above right). We again see the cadential trill with a plus, and the squiggle at the resolution (on a quarter, which is a long-ish note value in 3/8). Boismortier wants us to be sure to do a light trill (shorter appoggiatura, less pronounced) on the resolution, which makes sense because it's the end of a phrase and a resolution should have a sense of relief. And while it's entirely possible to do a more obvious appoggiatura on a resolution, that would generally indicate a different affect, perhaps more pathos, something more serious. That would not fit so well here as, the name indicates, this is a movement about charm and grace. So go for a gentle, light trill, and not too long (4 notes suffice!) and make sure it's in absolute diminuendo. It should almost sound like simply some kind of wavering in the air.

So I actually no longer think that these two symbols have so much to do with the LENGTH of the note/of the trill, but very much to do with how we approach the APPOGGIATURA, which will give different meanings to the ornament. The length of the trill itself will be dictated in part by the note value and the desired affect, but as these examples demonstrated, that doesn't seem to be the main reason for having these different signs.
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Take a look at other pieces of Boismortier, test my concepts and let me know what you find!

This is a shout-out to my friend Sophie.💜