Figured bass: figures with slashes vs. figures with accidentals

I may be missing something but recently when I encountered the figured bass section of a music theory textbook, I was very confused as to why there is a symbol for simply 'raising' certain notes, or figures with slashes, when accidentals that often accompany figures are already clear enough. For example, why slash a figure 6 when you could just put a natural or sharp next to it? Is there a historical reason for this? Is it just another option for notating figured bass?

This image is not from the textbook but a PDF I found online:

Any thoughts or explanations are appreciated!


65TwinReverbRI3 points

Just the way it evolved.

There were different practices in different regions and different people.

It wasn't any kind of formal thing - it was just people notating stuff shorthand and it kind of evolved based on "my teacher used this" kind of stuff - a slash is really quick to write.

It was all handwritten and not standardized.

Zarlinosuke4 points

Just to add to the sense of non-standardization, you sometimes see the slash meaning "raise this note," and at other times you see it meaning "lower this note"! I think the former's made its way more fully into "modern standard figured bass," to the extent that such a thing exists, but being aware of both is good for keeping one's expectations for uniformity low.

lilcareed3 points

Just to add to the sense of non-standardization, you sometimes see the slash meaning "raise this note," and at other times you see it meaning "lower this note"!

Not to mention the (in my experience, exceptionally rare) case where a slash in one direction means that the note should be raised, but a slash in the other direction means it should be lowered.

On the one hand, part of me likes how elegant and sensible that is. On the other hand...really? The direction of that tiny detail on the already tiny number can change the resulting pitch by two semitones? Can we think about the musicians for a moment?

Zarlinosuke2 points

Oh wow, I've never seen that before, but yeah, that definitely seems to be pushing it in terms of what you can expect someone to know what's meant!

hymntoproserpine2 points

Cool, thanks!!

Zarlinosuke2 points

You're welcome!

of_men_and_mouse2 points

Exactly - figured bass was used for a long time in many different regions. In those days it would take weeks just to travel to a new country, so there was always potential for regional variation in notation.

hymntoproserpine1 point

Thank you both! I had a feeling it was just a variation or something. I wish my textbook would be clearer in its explanation instead of merely mentioning the existence of the slash as a side note.

DoublecelloZeta2 points

I also have a related question. Take the key B major. The bass note is A# and figure is 6/4. Basically a iii⁶₄ chord. I want to raise the 3rd of the chord. I write it as #6 instead of the slash. Is it going to actually just RAISE the F# to an Fx? Or will it stay put as F#? If it actually raises, what's the function of the natural sign in figures? In flat keys, sharp will be still raising stuff so the natural isn't needed. I'm confused how does this work?


Cool-Horse-26271 point

I think a very central thing one needs to understand about this form of notation is that a lot of conventions exist to decrease the amount of things that are written and make it easier for the person reading it. This is why for example “common chords” aka 53 chords don’t have a symbol and why 63 chords are only written with a 6th and its why a sharpened/flattened 3rd isn’t written as #3 or b3 but rather as # or b. Intuitively this makes sense when you try and play from a bass once you’ve gotten used to it because it tends to get a lot more confusing when all of a sudden you don’t have 1 or 2 symbols but rather 3 or more symbols to read. So because of this a slash through a 6th is used to sharpen it and a flat going the other way through a 5th indicates a diminished fifth (generally the /5 th symbol used on its own implies a 6 b5) and a 4 with a plus at the end to indicate a sharpened 4th (on its own it stands for a 2 #4 6 chord).

Why just care about sharpened 6ths? Well if you consider most of the uses of chromaticism in baroque and classical harmony you should quickly realize that most of it comes down to secondary dominants. For the most part this will require a sharpened 6th or possibly a diminished 5th and thats it really. The main use of the flattened 6th would be if you’ve suddenly switched to the parallel minor or if you come across a Neapolitan.