Can we use double accidentals in figured bass?

Question

I've composed the following figured bass example:

It modulates from E to F and therefore needs several chromatic alterations. But my question is on the final beat of the third measure: if I want a B♭-minor chord here, is this the correct figured bass? As I see it, there are at least three possibilities for how to handle this chord:

1. Write it as I have; the ♮5 lowers F♯ to F♮ and the ♭♭3 lowers the D♯ to D♭.
2. Use a system where the figured bass shows the literal accidentals, not the adjustments from the key signature; in this system, ♮5 would give me F♮ and ♭3 would be enough to suggest D♭.
3. Use ♮♭3 to indicate first a change from the key signature's D♯ to D♮ and then a move from D♮ to D♭.

What would be the correct approach here? Ideally I would have a citation from a published figured bass manual (perhaps Heinichen?).

I've never seen a double accidental in a published figured bass before, likely because that repertoire doesn't often get this chromatic. As such, I'm uncertain how best to notate this.

Answer 1

This is a cut and paste answer so please consider double checking my source, I could have taken this paragraph out of context. The frustrating thing is there are no musical illustrations regarding figures with double sharps/flats to go with the rule! I scanned the other pages but could not find an example. Anyhow, your first choice matches up with Albrechtsberger.

• https://books.google.com/books?id=kjoDAAAAQAAJ

...page 35 or 36 in the Google book.

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EDIT

I was able to find a double sharp figure further into the book. The illustration shows both the accidental in the figured bass and in a full notated chord. The figure and notation accidentals match...

I think this makes Albrechtsberger's meaning clear, and it is the meaning I original thought he meant. Whatever accidental would be used in notation, that will be the accidental to use on a figure for a 3 interval.

That example from p.56 isn't a double flat/double sharp, but it shows a flat in the key signature being raised. In notation that change is achieved with a natural sign. In the bass figure it is not a case of using sharp to mean "raise by a half step" but instead it matches the accidental of the staff notation.

I didn't find a double flat example, but I imagine it would follow the same course and that Richard's 𝄫3 would seem to follow Albrechtsberger.